modélisation des écoulements aux très petites échelles
écoulements multiphasiques à phases séparées
thermohydraulique en production d'énergie nucléaire.
Axe de recherche :
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Micro-objets déformables sous forçage hydrodynamique (voir les détails sur la page dédiée)
Publications scientifiques au M2P2
2024
Julian Wailliez, Paul Regazzi, Anniina Salonen, Paul G Chen, Marc Jaeger, et al.. Drop deformation in a planar elongational flow: impact of surfactant dynamics. Soft Matter, 2024, 20 (44), pp.8793-8803. ⟨10.1039/D4SM00642A⟩. ⟨hal-04740537v2⟩ Plus de détails...
Drops in extensional flow undergo a deformation, which is primarily fixed by a balance between their surface tension and the viscous stress. This deformation, predicted and measured by Taylor on millimetric drops, is expected to be affected by the presence of surfactants but has never been measured systematically. We provide a controlled experiment allowing to measure this deformation as a function of the drop size and of the shear stress for different surfactants at varying concentrations. Our observation is that the deformation predicted by Taylor is recovered at zero and high surfactant concentration, whereas it is smaller at concentrations close to the critical micellar concentration. This is in contradiction with the existing analytical models. We develop a new analytical model, taking into account the surfactant dynamics. The model predicts a transition between a deformation similar to the one of a pure liquid and a smaller one. We show that the transition is driven by a parameter K_L , which compares adsorption and desorption dynamics. Finally, the concentration C* , at which we observe this transition in the extensional flow is in good agreement with the one predicted by independent measurement of K_L .
Julian Wailliez, Paul Regazzi, Anniina Salonen, Paul G Chen, Marc Jaeger, et al.. Drop deformation in a planar elongational flow: impact of surfactant dynamics. Soft Matter, 2024, 20 (44), pp.8793-8803. ⟨10.1039/D4SM00642A⟩. ⟨hal-04740537v2⟩
V Puthumana, Paul G. Chen, M Leonetti, R Lasserre, M Jaeger. Assessment of coupled bilayer-cytoskeleton modelling strategy for red blood cell dynamics in flow. Journal of Fluid Mechanics, 2024, 979, pp.A44. ⟨10.1017/jfm.2023.1092⟩. ⟨hal-04409136⟩ Plus de détails...
The red blood cell (RBC) membrane is composed of a lipid bilayer and a cytoskeleton interconnected by protein junction complexes, allowing for potential sliding between the lipid bilayer and the cytoskeleton. Despite this biological reality, it is most often modelled as a single-layer model, a hyperelastic capsule or a fluid vesicle. Another approach involves incorporating the membrane's composite structure using double layers, where one layer represents the lipid bilayer and the other represents the cytoskeleton. In this paper, we computationally assess the various modelling strategies by analysing RBC behaviour in extensional flow and four distinct regimes that simulate RBC dynamics in shear flow. The proposed double-layer strategies, such as the vesicle--capsule and capsule--capsule models, account for the fluidity and surface incompressibility of the lipid bilayer in different ways. Our findings demonstrate that introducing sliding between the layers offers the cytoskeleton a considerable degree of freedom to alleviate its elastic stresses, resulting in a significant increase in RBC elongation. Surprisingly, our study reveals that the membrane modelling strategy for RBCs holds greater importance than the choice of the cytoskeleton's reference shape. These results highlight the inadequacy of considering mechanical properties alone and emphasise the need for careful integration of these properties. Furthermore, our findings fortuitously uncover a novel indicator for determining the appropriate stress-free shape of the cytoskeleton.
V Puthumana, Paul G. Chen, M Leonetti, R Lasserre, M Jaeger. Assessment of coupled bilayer-cytoskeleton modelling strategy for red blood cell dynamics in flow. Journal of Fluid Mechanics, 2024, 979, pp.A44. ⟨10.1017/jfm.2023.1092⟩. ⟨hal-04409136⟩
Jinming Lyu, Paul G. Chen, Alexander Farutin, Marc Jaeger, Chaouqi Misbah, et al.. Swirling of vesicles: Shapes and dynamics in Poiseuille flow as a model of RBC microcirculation. Physical Review Fluids, 2023, 8 (2), pp.L021602. ⟨10.1103/PhysRevFluids.8.L021602⟩. ⟨hal-03979358v2⟩ Plus de détails...
We report on a systematic numerical exploration of the vesicle dynamics in a channel, which is a model of red blood cells in microcirculation. We find a spontaneous transition, called swirling, from straight motion with axisymmetric shape to a motion along a helix with a stationary deformed shape that rolls on itself and spins around the flow direction. We also report on a planar oscillatory motion of the mass center, called three-dimensional snaking for which the shape deforms periodically. Both emerge from supercritical pitchfork bifurcation with the same threshold. The universality of these oscillatory dynamics emerges from Hopf bifurcations with two order parameters. These two oscillatory dynamics are put in the context of vesicle shape and dynamics in the parameter space of reduced volume v, capillary number, and confinement. Phase diagrams are established for v = 0.95, v = 0.9, and v = 0.85 showing that oscillatory dynamics appears if the vesicle is sufficiently deflated. Stationary shapes (parachute/bullet/peanut, croissant, and slipper) are fixed points, while swirling and snaking are characterized by two limit cycles.
Jinming Lyu, Paul G. Chen, Alexander Farutin, Marc Jaeger, Chaouqi Misbah, et al.. Swirling of vesicles: Shapes and dynamics in Poiseuille flow as a model of RBC microcirculation. Physical Review Fluids, 2023, 8 (2), pp.L021602. ⟨10.1103/PhysRevFluids.8.L021602⟩. ⟨hal-03979358v2⟩
Revaz Chachanidze, Kaili Xie, Jinming Lyu, Marc Jaeger, Marc Leonetti. Breakups of Chitosan microcapsules in extensional flow. Journal of Colloid and Interface Science, 2023, 629, pp.445-454. ⟨10.1016/j.jcis.2022.08.169⟩. ⟨hal-03787637⟩ Plus de détails...
The controlled rupture of a core-shell capsule and the timely release of encapsulated materials are essential steps of the efficient design of such carriers. The mechanical and physico-chemical properties of their shells (or membranes) mainly govern the evolution of such systems under stress and notably the link between the dynamics of rupture and the mechanical properties. This issue is addressed considering weakly cohesive shells made by the interfacial complexation of Chitosan and PFacid in a planar extensional flow. Three regimes are observed, thanks to the two observational planes. Whatever the time of reaction in membrane assembly, there is no rupture in deformation as long as the hydrodynamic stress is below a critical value. At low times of complexation (weak shear elastic modulus), the rupture is reminiscent of the breakup of droplets: a dumbell or a waist. Fluorescent labelling of the membrane shows that this process is governed by continuous thinning of the membrane up to the destabilization. It is likely that the membrane shows a transition from a solid to liquid state. At longer times of complexation, the rupture has a feature of solid-like breakup (breakage) with a discontinuity of the membrane. The maximal internal constraint determined numerically marks the initial location of breakup as shown. The pattern becomes more complex as the elongation rate increases with several points of rupture. A phase diagram in the space parameters of the shear elastic modulus and the hydrodynamic stress is established.
Revaz Chachanidze, Kaili Xie, Jinming Lyu, Marc Jaeger, Marc Leonetti. Breakups of Chitosan microcapsules in extensional flow. Journal of Colloid and Interface Science, 2023, 629, pp.445-454. ⟨10.1016/j.jcis.2022.08.169⟩. ⟨hal-03787637⟩
Sudip Das, Marc Jaeger, Marc Leonetti, Rochish M. Thaokar, Paul G. Chen. Effect of pulse width on the dynamics of a deflated vesicle in unipolar and bipolar pulsed electric fields. Physics of Fluids, 2021, 33 (8), pp.081905. ⟨10.1063/5.0057168⟩. ⟨hal-03317441⟩ Plus de détails...
Giant unilamellar vesicles subjected to pulsed direct-current (pulsed-DC) fields are promising biomimetic systems to investigate the electroporation of cells. In strong electric fields, vesicles undergo significant deformation, which strongly alters the transmembrane potential, consequently the electroporation. Previous theoretical studies investigated the electrodeformation of vesicles in DC fields (which are not pulsed). In this work, we computationally investigate the deformation of a deflated vesicle under unipolar, bipolar, and two-step unipolar pulses and show sensitive dependence of intermediate shapes on type of pulse and the pulse width. Starting with the stress-free initial shape of a deflated vesicle, which is similar to a prolate spheroid, the analysis is presented for the cases with higher and lower conductivities of the inner fluid medium relative to the outer fluid medium. For the ratio of inner to outer fluid conductivity, σ r = 10, the shape always remains prolate, including when the field is turned off. For σ r = 0.1, several complex dynamics are observed, such as the prolate-to-oblate (PO), prolate-to-oblate-to-prolate (POP) shape transitions in time depending upon the strength of the field and the pulse properties. In this case, on turning off the field, a metastable oblate equilibrium shape is seen, that seems to be a characteristics of a deflated vesicle leading to POPO transitions. When a two-step unipolar pulse (a combination of a strong and a weak subpulse) is applied, a vesicle can reach an oblate or a prolate final shape depending upon the relative durations of the two subpulses. This study suggests that the transmembrane potential can be regulated using a bipolar pulsed-DC field. It also shows that the shapes admitted in the dynamics of a vesicle depends upon whether the pulse is unipolar or bipolar. Parameters are suggested wherein, the simulation results can be demonstrated in experiments.
Sudip Das, Marc Jaeger, Marc Leonetti, Rochish M. Thaokar, Paul G. Chen. Effect of pulse width on the dynamics of a deflated vesicle in unipolar and bipolar pulsed electric fields. Physics of Fluids, 2021, 33 (8), pp.081905. ⟨10.1063/5.0057168⟩. ⟨hal-03317441⟩
J. M. Lyu, Paul G. Chen, G. Boedec, M. Leonetti, M. Jaeger, et al.. An isogeometric boundary element method for soft particles flowing in microfluidic channels. Computers and Fluids, Elsevier, 2021, 214, pp.104786. ⟨10.1016/j.compfluid.2020.104786⟩. ⟨hal-03082862⟩ Plus de détails...
Understanding the flow of deformable particles such as liquid drops, synthetic capsules and vesicles, and biological cells confined in a small channel is essential to a wide range of potential chemical and biomedical engineering applications. Computer simulations of this kind of fluid-structure (membrane) interaction in low-Reynolds-number flows raise significant challenges faced by an intricate interplay between flow stresses, complex particles' interfacial mechanical properties, and fluidic confinement. Here, we present an isogeometric computational framework by combining the finite-element method (FEM) and boundary-element method (BEM) for an accurate prediction of the deformation and motion of a single soft particle transported in microfluidic channels. The proposed numerical framework is constructed consistently with the isogeometric analysis paradigm; Loop's subdivision elements are used not only for the representation of geometry but also for the membrane mechanics solver (FEM) and the interfacial fluid dynamics solver (BEM). We validate our approach by comparison of the simulation results with highly accurate benchmark solutions to two well-known examples available in the literature, namely a liquid drop with constant surface tension in a circular tube and a capsule with a very thin hyperelastic membrane in a square channel. We show that the numerical method exhibits second-order convergence in both time and space. To further demonstrate the accuracy and long-time numerically stable simulations of the algorithm, we perform hydrodynamic computations of a lipid vesicle with bending stiffness and a red blood cell with a composite membrane in capillaries. The present work offers some possibilities to study the deformation behavior of confining soft particles, especially the particles' shape transition and dynamics and their rheological signature in channel flows.
J. M. Lyu, Paul G. Chen, G. Boedec, M. Leonetti, M. Jaeger, et al.. An isogeometric boundary element method for soft particles flowing in microfluidic channels. Computers and Fluids, Elsevier, 2021, 214, pp.104786. ⟨10.1016/j.compfluid.2020.104786⟩. ⟨hal-03082862⟩
Jinming Lyu, Paul G. Chen, G. Boedec, M. Leonetti, Marc Jaeger. An isogeometric boundary element method for soft particles flowing in microfluidic channels. Computers and Fluids, 2021, 214, pp.104786. ⟨10.1016/j.compfluid.2020.104786⟩. ⟨hal-02476945v2⟩ Plus de détails...
Understanding the flow of deformable particles such as liquid drops, synthetic capsules and vesicles, and biological cells confined in a small channel is essential to a wide range of potential chemical and biomedical engineering applications. Computer simulations of this kind of fluid-structure (mem-brane) interaction in low-Reynolds-number flows raise significant challenges faced by an intricate interplay between flow stresses, complex particles' in-terfacial mechanical properties, and fluidic confinement. Here, we present an isogeometric computational framework by combining the finite-element method (FEM) and boundary-element method (BEM) for an accurate prediction of the deformation and motion of a single soft particle transported in microfluidic channels. The proposed numerical framework is constructed consistently with the isogeometric analysis paradigm; Loop's subdivision elements are used not only for the representation of geometry but also for the membrane mechanics solver (FEM) and the interfacial fluid dynamics solver (BEM). We validate our approach by comparison of the simulation results with highly accurate benchmark solutions to two well-known examples available in the literature, namely a liquid drop with constant surface tension in a circular tube and a capsule with a very thin hyperelastic membrane in a square channel. We show that the numerical method exhibits second-order convergence in both time and space. To further demonstrate the accuracy and long-time numerically stable simulations of the algorithm, we perform hydrodynamic computations of a lipid vesicle with bending stiffness and a red blood cell with a composite membrane in capillaries. The present work offers some possibilities to study the deformation behavior of confining soft particles, especially the particles' shape transition and dynamics and their rheological signature in channel flows.
Jinming Lyu, Paul G. Chen, G. Boedec, M. Leonetti, Marc Jaeger. An isogeometric boundary element method for soft particles flowing in microfluidic channels. Computers and Fluids, 2021, 214, pp.104786. ⟨10.1016/j.compfluid.2020.104786⟩. ⟨hal-02476945v2⟩
Paul G. Chen, J M Lyu, M Jaeger, M. Leonetti. Shape transition and hydrodynamics of vesicles in tube flow. Physical Review Fluids, 2020, 5 (4), pp.043602. ⟨10.1103/PhysRevFluids.5.043602⟩. ⟨hal-02415320v2⟩ Plus de détails...
The steady motion and deformation of a lipid-bilayer vesicle translating through a circular tube in low Reynolds number pressure-driven flow are investigated numerically using an axisymmetric boundary element method. This fluid-structure interaction problem is determined by three dimen-sionless parameters: reduced volume (a measure of the vesicle asphericity), geometric confinement (the ratio of the vesicle effective radius to the tube radius), and capillary number (the ratio of viscous to bending forces). The physical constraints of a vesicle--fixed surface area and enclosed volume when it is confined in a tube--determine critical confinement beyond which it cannot pass through without rupturing its membrane. The simulated results are presented in a wide range of reduced volumes [0.6, 0.98] for different degrees of confinement; the reduced volume of 0.6 mimics red blood cells. We draw a phase diagram of vesicle shapes and propose a shape transition line separating the parachutelike shape region from the bulletlike one in the reduced volume versus confinement phase space. We show that the shape transition marks a change in the behavior of vesicle mobility, especially for highly deflated vesicles. Most importantly, high-resolution simulations make it possible for us to examine the hydrodynamic interaction between the wall boundary and the vesicle surface at conditions of very high confinement, thus providing the limiting behavior of several quantities of interest, such as the thickness of lubrication film, vesicle mobility and its length, and the extra pressure drop due to the presence of the vesicle. This extra pressure drop holds implications for the rheology of dilute vesicle suspensions. Furthermore, we present various correlations and discuss a number of practical applications. The results of this work may serve as a benchmark for future studies and help devise tube-flow experiments.
Paul G. Chen, J M Lyu, M Jaeger, M. Leonetti. Shape transition and hydrodynamics of vesicles in tube flow. Physical Review Fluids, 2020, 5 (4), pp.043602. ⟨10.1103/PhysRevFluids.5.043602⟩. ⟨hal-02415320v2⟩
T. Dupuy, T. Prusek, F. Oukacine, M. Lacroix, A. Kaiss, et al.. Fractal description of fouling deposits in boiling heat transfer modelling. International Journal of Heat and Mass Transfer, 2019, 145, pp.118722. ⟨10.1016/j.ijheatmasstransfer.2019.118722⟩. ⟨hal-02467974⟩ Plus de détails...
A novel methodology is developed for predicting the thermal impact of fouling in Steam Generators (SG). The originality of this methodology is to resort to fractal and statistical theories to depict the porous structure of the deposits. The proposed Statistical Fractal methodology (SF) accounts for the heat transfer driven by the liquid-vapor phase change inside the deposits. It simulates the complex intricate networks of sinuous open pores of different scales, with liquid inflows (capillaries) and vapor outflows (steam-chimneys). The multi-layered representation of fouling deposits allows to mimic aging mechanisms such as densification which occur during SG operation.The SF predictions are consistent with experimental data. The deposit thickness and the profile of porosity are found to be the most influential fouling properties on the heat exchange. The methodology is capable to simulate the experimentally observed heat transfer enhancement for thin and porous deposit as well as the heat exchange decline for thick and dense deposit.
T. Dupuy, T. Prusek, F. Oukacine, M. Lacroix, A. Kaiss, et al.. Fractal description of fouling deposits in boiling heat transfer modelling. International Journal of Heat and Mass Transfer, 2019, 145, pp.118722. ⟨10.1016/j.ijheatmasstransfer.2019.118722⟩. ⟨hal-02467974⟩
Journal: International Journal of Heat and Mass Transfer
T. Dupuy, T. Prusek, F. Oukacine, M. Lacroix, A. Kaiss, et al.. Fractal description of fouling deposits in boiling heat transfer modelling. International Journal of Heat and Mass Transfer, Elsevier, 2019, 145, pp.118722. ⟨10.1016/j.ijheatmasstransfer.2019.118722⟩. ⟨hal-02467974⟩ Plus de détails...
A novel methodology is developed for predicting the thermal impact of fouling in Steam Generators (SG). The originality of this methodology is to resort to fractal and statistical theories to depict the porous structure of the deposits. The proposed Statistical Fractal methodology (SF) accounts for the heat transfer driven by the liquid-vapor phase change inside the deposits. It simulates the complex intricate networks of sinuous open pores of different scales, with liquid inflows (capillaries) and vapor outflows (steam-chimneys). The multi-layered representation of fouling deposits allows to mimic aging mechanisms such as densification which occur during SG operation. The SF predictions are consistent with experimental data. The deposit thickness and the profile of porosity are found to be the most influential fouling properties on the heat exchange. The methodology is capable to simulate the experimentally observed heat transfer enhancement for thin and porous deposit as well as the heat exchange decline for thick and dense deposit.
T. Dupuy, T. Prusek, F. Oukacine, M. Lacroix, A. Kaiss, et al.. Fractal description of fouling deposits in boiling heat transfer modelling. International Journal of Heat and Mass Transfer, Elsevier, 2019, 145, pp.118722. ⟨10.1016/j.ijheatmasstransfer.2019.118722⟩. ⟨hal-02467974⟩
Journal: International Journal of Heat and Mass Transfer
C. Lebrun, S. Vukusic, V. Abadie, C. Achour, F. Ader, et al.. Immunization and multiple sclerosis: Recommendations from the French Multiple Sclerosis Society. Revue Neurologique, Elsevier Masson, 2019, 175 (6), pp.341-357. ⟨10.1016/j.neurol.2019.04.001⟩. ⟨hal-02546158⟩ Plus de détails...
Objectives: To establish recommendations on immunization for patients with multiple sclerosis (MS).Background: Vaccines have been suspected in the past to trigger MS and relapses. With the extension of the immunoactive treatment arsenal, other concerns have been raised more recently about an increased risk of infection or a decreased effectiveness of immunization in immunosuppressed patients.Methods: The French Group for Recommendations into Multiple Sclerosis (France4MS) performed a systematic search of papers in Medline and other university databases (January 1975-June 2018). The RAND/UCLA appropriateness method was chosen to review the scientific literature and to formalize the degree of agreement among experts on 5 clinical questions related to immunization and MS. Readers from the steering committee conducted a systematic analysis, wrote a critical synthesis and prepared a list of proposals that were evaluated by a rating group of 28 MS experts. The final version of the recommendations was finally reviewed by a reading group of 110 health care professionals and classified as appropriate, inappropriate or uncertain.Results: Neurologists should verify the vaccination status as soon as MS is diagnosed and before disease-modifying treatments (DMTs) are introduced. The French vaccination schedule applies to MS patients and seasonal influenza vaccination is recommended. In the case of treatment-induced immunosuppression, MS patients should be informed about the risk of infection and the vaccination standards of the French High Council of Health should be applied. Live attenuated vaccines are contra-indicated in patients recently treated with immunosuppressive drugs, including corticosteroids; other vaccines can be proposed whatever the treatment, but their effectiveness may be partly reduced with some drugs.Conclusion: Physicians and patients should be aware of the updated recommendations for immunizations of patients with MS.
C. Lebrun, S. Vukusic, V. Abadie, C. Achour, F. Ader, et al.. Immunization and multiple sclerosis: Recommendations from the French Multiple Sclerosis Society. Revue Neurologique, Elsevier Masson, 2019, 175 (6), pp.341-357. ⟨10.1016/j.neurol.2019.04.001⟩. ⟨hal-02546158⟩
Jinming Lyu, Paul G. Chen, Gwenn Boedec, Marc Leonetti, Marc Jaeger. Hybrid continuum–coarse-grained modeling of erythrocytes. Comptes Rendus Mécanique, 2018, 346, pp.439-448. ⟨10.1016/j.crme.2018.04.015⟩. ⟨hal-01785429⟩ Plus de détails...
The red blood cell (RBC) membrane is a composite structure, consisting of a phospholipid bilayer and an underlying membrane-associated cytoskeleton. Both continuum and particle-based coarse-grained RBC models make use of a set of vertices connected by edges to represent the RBC membrane, which can be seen as a triangular surface mesh for the former and a spring network for the latter. Here, we present a modeling approach combining an existing continuum vesicle model with a coarse-grained model for the cytoskeleton. Compared to other two-component approaches, our method relies on only one mesh, representing the cytoskeleton, whose velocity in the tangential direction of the membrane may be different from that of the lipid bilayer. The finitely extensible nonlinear elastic (FENE) spring force law in combination with a repulsive force defined as a power function (POW), called FENE-POW, is used to describe the elastic properties of the RBC membrane. The mechanical interaction between the lipid bilayer and the cytoskeleton is explicitly computed and incorporated into the vesicle model. Our model includes the fundamental mechanical properties of the RBC membrane, namely fluidity and bending rigidity of the lipid bilayer, and shear elasticity of the cytoskeleton while maintaining surface-area and volume conservation constraint. We present three simulation examples to demonstrate the effectiveness of this hybrid continuum--coarse-grained model for the study of RBCs in fluid flows.
Jinming Lyu, Paul G. Chen, Gwenn Boedec, Marc Leonetti, Marc Jaeger. Hybrid continuum–coarse-grained modeling of erythrocytes. Comptes Rendus Mécanique, 2018, 346, pp.439-448. ⟨10.1016/j.crme.2018.04.015⟩. ⟨hal-01785429⟩
Mustapha-Kamel Khelloufi, Etienne Loiseau, Marc Jaeger, Nicolas Molinari, Pascal Chanez, et al.. Spatiotemporal organization of cilia drives multiscale mucus swirls in model human bronchial epithelium. Scientific Reports, 2018, 8, pp.2447. ⟨10.1038/s41598-018-20882-4⟩. ⟨hal-01821276⟩ Plus de détails...
Mucociliary clearance is a biomechanical mechanism of airway protection. It consists of the active transport along the bronchial tree of the mucus, a fluid propelled by the coordinated beating of a myriad of cilia on the epithelial surface of the respiratory tract. The physics of mucus transport is poorly understood because it involves complex phenomena such as long-range hydrodynamic interactions, active collective ciliary motion, and the complex rheology of mucus. We propose a quantitative physical analysis of the ciliary activity and mucus transport on a large panel of human bronchial cultures from control subjects, patients with asthma and chronic obstructive pulmonary disease obtained from endobronchial biopsies. Here we report on the existence of multiple ciliary domains with sizes ranging from the tens of a micron to the centimeter, where ciliary beats present a circular orientational order. These domains are associated with circular mucus flow patterns, whose size scales with the average cilia density. In these domains, we find that the radial increase of the ciliated cell density coupled with the increase in the orientational order of ciliary beats result in a net local force proportional to the mucus velocity. We propose a phenomenological physical model that supports our results.
Mustapha-Kamel Khelloufi, Etienne Loiseau, Marc Jaeger, Nicolas Molinari, Pascal Chanez, et al.. Spatiotemporal organization of cilia drives multiscale mucus swirls in model human bronchial epithelium. Scientific Reports, 2018, 8, pp.2447. ⟨10.1038/s41598-018-20882-4⟩. ⟨hal-01821276⟩
Gwenn Boedec, Marc Leonetti, Marc Jaeger. Isogeometric FEM-BEM simulations of drop, capsule and vesicle dynamics in Stokes flow. Journal of Computational Physics, 2017, 342, pp.117 - 138. ⟨10.1016/j.jcp.2017.04.024⟩. ⟨hal-01590257⟩ Plus de détails...
We develop an algorithm for the three dimensional simulation of the dynamics of soft objects (drops, capsules, vesicles) under creeping flow conditions. Loop elements are used to describe the shape of the soft objects. This surface representation is used both for membrane solver based on finite element method (FEM) and for the fluid solver based on the boundary element method (BEM). This isogeometric analysis of the low Reynolds fluid-structure interaction problem is then coupled to high-order explicit time stepping or second-order implicit time stepping algorithm. For vesicles simulation, a preconditioner is designed for the resolution of the surface velocity incompressibility constraint, which is treated by the use of a local Lagrange multiplier. A mesh quality preserving algorithm is introduced to improve the control mesh quality over long simulation times. We test the proposed algorithm on capsule and vesicle dynamics in various flows, and study its convergence properties, showing a second-order convergence O(N-2) with mesh number of elements.
Gwenn Boedec, Marc Leonetti, Marc Jaeger. Isogeometric FEM-BEM simulations of drop, capsule and vesicle dynamics in Stokes flow. Journal of Computational Physics, 2017, 342, pp.117 - 138. ⟨10.1016/j.jcp.2017.04.024⟩. ⟨hal-01590257⟩
Kaili Xie, Clement de Loubens, Frédéric Dubreuil, Deniz Gunes, Marc Jaeger, et al.. Interfacial rheological properties of self-assembling biopolymer microcapsules. Soft Matter, 2017, 13 (36), pp.6208-6217. ⟨10.1039/C7SM01377A⟩. ⟨hal-02020103⟩ Plus de détails...
Tuning the mechanical properties of microcapsules with cost-efficient route of fabrication is still a challenge. The traditional method of layer-by-layer assembly of microcapsules allows building a tailored composite multi-layer membrane but is technically complex as it requires numerous steps. The objective of this article is to characterize the interfacial rheological properties of self-assembling biopolymer microcapsules that were obtained in one single facile step. This thorough study provides new insights in the mechanics of these weakly cohesive membranes. Firstly, sus-pensions of water-in-oil microcapsules were formed in microfluidic junctions by self-assembling of two oppositely charged polyelectrolytes, namely chitosan (water soluble) and phosphatidic fatty acid (oil soluble). In this way, composite membranes of tunable thickness (between 40-900 nm measured by AFM) were formed at water / oil interfaces in a single step by changing the composition. Secondly, microcapsules were mechanically characterized by stretching them up to break-up in an extensional flow chamber which extends the relevance and convenience of the hydrodynamic method to weakly cohesive membranes. Finally, we show that the design of micro-capsules can be 'engineered' in a large way since they present a wealth of interfacial rheological properties in term of elasticity, plasticity and yield stress whose magnitudes can be controlled by the composition. These behaviors are explained by the variation of the membrane thickness with the physico-chemical parameters of the process.
Kaili Xie, Clement de Loubens, Frédéric Dubreuil, Deniz Gunes, Marc Jaeger, et al.. Interfacial rheological properties of self-assembling biopolymer microcapsules. Soft Matter, 2017, 13 (36), pp.6208-6217. ⟨10.1039/C7SM01377A⟩. ⟨hal-02020103⟩
U. Laux, B. Stecklum, P. Bacci, M. Maestripieri, M. Carotta, et al.. 2017 OH7. Minor Planet Electronic Circulars, 2017. ⟨hal-02268848⟩ Plus de détails...
N. A. R. O. Nicolini Astronomical Robotic Observatory
K. Sárneczky
A. Ordasi
L. Hudin
L. Denneau
A. Heinze
H. Weiland
B. Stalder
J. Tonry
C. Jacques
E. Pimentel
J. Barros
G. Wells
J. Leuty
D. Bamberger
2017
M. Dennefeld, W. Brzezinska, M. Nowak, F. Spoto, W. Thuillot, et al.. Comet P/2017 s5 (atlas). Minor Planet Electronic Circulars, 2017. ⟨hal-02268847⟩ Plus de détails...
J. Gounley, G. Boedec, Marc Jaeger, M. Leonetti. Influence of surface viscosity on droplets in shear flow. Journal of Fluid Mechanics, 2016, 791, pp.464- 494. ⟨10.1017/jfm.2016.39⟩. ⟨hal-01281643⟩ Plus de détails...
The behaviour of a single droplet in an immiscible external fluid, submitted to shear flow is investigated using numerical simulations. The surface of the droplet is modelled by a Boussinesq–Scriven constitutive law involving the interfacial viscosities and a constant surface tension. A numerical method using Loop subdivision surfaces to represent droplet interface is introduced. This method couples boundary element method for fluid flows and finite element method to take into account the stresses due to the surface dilational and shear viscosities and surface tension. Validation of the numerical scheme with respect to previous analytic and computational work is provided, with particular attention to the viscosity contrast and the shear and dilational viscosities characterized both by a Boussinesq number Bq. Then, influence of equal surface viscosities on steady-state characteristics of a droplet in shear flow are studied, considering both small and large deformations and for a large range of bulk viscosity contrast. We find that small deformation analysis is surprisingly predictive at moderate and high surface viscosities. Equal surface viscosities decrease the Taylor deformation parameter and tank-treading angle and also strongly modify the dynamics of the droplet: when the Boussinesq number (surface viscosity) is large relative to the capillary number (surface tension), the droplet displays damped oscillations prior to steady-state tank-treading, reminiscent from the behaviour at large viscosity contrast. In the limit of infinite capillary number Ca, such oscillations are permanent. The influence of surface viscosities on breakup is also investigated, and results show that the critical capillary number is increased. A diagram (Bq;Ca) of breakup is established with the same inner and outer bulk viscosities. Additionally, the separate roles of shear and dilational surface viscosity are also elucidated, extending results from small deformation analysis. Indeed, shear (dilational) surface viscosity increases (decreases) the stability of drops to breakup under shear flow. The steady-state deformation (Taylor parameter) varies nonlinearly with each Boussinesq number or a linear combination of both Boussinesq numbers. Finally, the study shows that for certain combinations of shear and dilational viscosities, drop deformation for a given capillary number is the same as in the case of a clean surface while the inclination angle varies.
J. Gounley, G. Boedec, Marc Jaeger, M. Leonetti. Influence of surface viscosity on droplets in shear flow. Journal of Fluid Mechanics, 2016, 791, pp.464- 494. ⟨10.1017/jfm.2016.39⟩. ⟨hal-01281643⟩
R. Trozzo, G. Boedec, M. Leonetti, M. Jaeger. Axisymmetric Boundary Element Method for vesicles in a capillary. Journal of Computational Physics, 2015, 289, pp.62-82. ⟨10.1016/j.jcp.2015.02.022⟩. ⟨hal-01281961⟩ Plus de détails...
The problem of a vesicle transported by a fluid flow can present a large range of length scales. One example is the case of a vesicle producing a tether, and eventually pearls, in an elongational flow. Another case occurs when a lubrication film is formed, such as during the short range interaction between two vesicles. Such problems are still challenging for 3D simulations. On the other hand, a good understanding could be obtained by first considering the axisymmetric regime when such a regime exists. An axisymmetric model could then be used, without the criticisms that can be made of a 2D approach. We propose such a model, primarily interested in flows through narrow cylindrical capillaries. Two options are compared, with and without explicit representation of the capillary boundaries by a mesh. The numerical effort is characterized as a function of the vesicle’s initial shape, the flow magnitude and the confinement. The model is able to treat typical configurations of red blood cells flowing through very narrow pores with extremely thin lubrication films.
R. Trozzo, G. Boedec, M. Leonetti, M. Jaeger. Axisymmetric Boundary Element Method for vesicles in a capillary. Journal of Computational Physics, 2015, 289, pp.62-82. ⟨10.1016/j.jcp.2015.02.022⟩. ⟨hal-01281961⟩
M. Jaeger, G. Deiana, S. Nash, J.-Y. Bar, F. Cotton, et al.. Prognostic factors of long-term outcome in cases of severe traumatic brain injury. Annals of Physical and Rehabilitation Medicine, 2014, 57 (6-7), pp.436-451. ⟨10.1016/j.rehab.2014.06.001⟩. ⟨hal-02083254⟩ Plus de détails...
M. Jaeger, G. Deiana, S. Nash, J.-Y. Bar, F. Cotton, et al.. Prognostic factors of long-term outcome in cases of severe traumatic brain injury. Annals of Physical and Rehabilitation Medicine, 2014, 57 (6-7), pp.436-451. ⟨10.1016/j.rehab.2014.06.001⟩. ⟨hal-02083254⟩
Journal: Annals of Physical and Rehabilitation Medicine
G. Boedec, Marc Jaeger, Marc Leonetti. Pearling instability of a cylindrical vesicle. Journal of Fluid Mechanics, 2014, 743, pp.262-279. ⟨10.1017/jfm.2014.34⟩. ⟨hal-01050140⟩ Plus de détails...
A cylindrical vesicle under tension can undergo a pearling instability, characterized by the growth of a sinusoidal perturbation which evolves towards a collection of quasi-spherical bulbs connected by thin tethers, like pearls on a necklace. This is reminiscent of the well-known Rayleigh-Plateau instability, where surface tension drives the amplification of sinusoidal perturbations of a cylinder of fluid. We calculate the growth rate of perturbations for a cylindrical vesicle under tension, considering the effect of both inner and outer fluids, with different viscosities. We show that this situation differs strongly from the classical Rayleigh-Plateau case in the sense that, first, the tension must be above a critical value for the instability to develop and, second, even in the strong tension limit, the surface preservation constraint imposed by the presence of the membrane leads to a different asymptotic behaviour. The results differ from previous studies on pearling due to the consideration of variations of tension, which are shown to enhance the pearling instability growth rate, and lower the wavenumber of the fastest growing mode.
G. Boedec, Marc Jaeger, Marc Leonetti. Pearling instability of a cylindrical vesicle. Journal of Fluid Mechanics, 2014, 743, pp.262-279. ⟨10.1017/jfm.2014.34⟩. ⟨hal-01050140⟩
Gwenn Boedec, Marc Jaeger, Marc Leonetti. Pearling instability of a cylindrical vesicle. Journal of Fluid Mechanics, 2014, 743, pp.262-279. ⟨10.1017/jfm.2014.34⟩. ⟨hal-01050140⟩ Plus de détails...
A cylindrical vesicle under tension can undergo a pearling instability, characterized by the growth of a sinusoidal perturbation which evolves towards a collection of quasi-spherical bulbs connected by thin tethers, like pearls on a necklace. This is reminiscent of the well-known Rayleigh-Plateau instability, where surface tension drives the amplification of sinusoidal perturbations of a cylinder of fluid. We calculate the growth rate of perturbations for a cylindrical vesicle under tension, considering the effect of both inner and outer fluids, with different viscosities. We show that this situation differs strongly from the classical Rayleigh-Plateau case in the sense that, first, the tension must be above a critical value for the instability to develop and, second, even in the strong tension limit, the surface preservation constraint imposed by the presence of the membrane leads to a different asymptotic behaviour. The results differ from previous studies on pearling due to the consideration of variations of tension, which are shown to enhance the pearling instability growth rate, and lower the wavenumber of the fastest growing mode.
Gwenn Boedec, Marc Jaeger, Marc Leonetti. Pearling instability of a cylindrical vesicle. Journal of Fluid Mechanics, 2014, 743, pp.262-279. ⟨10.1017/jfm.2014.34⟩. ⟨hal-01050140⟩
Marc Leonetti, Gwenn Boedec, Marc Jaeger. Breathing instability in biological cells, patterns of membrane proteins. Discontinuity, Nonlinearity, and Complexity, 2013, 2 (1), pp.75-84. ⟨10.5890/DNC.2012.12.001⟩. ⟨hal-00997680⟩ Plus de détails...
The activity of biological cells involves often the electric activity of its membranes which exhibit various spatiotemporal dynamics, from pulse, oscillatory bifurcation to stationary spatial modulation. This last kind of patterns appears on a typical diffusive time. A model has been proposed implying a coupling between the current flowing through membrane proteins and their electrophoretic motions in the case of mobile proteins. Here, we study the stability of the pattern in a 2D circular model cell versus the appearance of standing waves, the so-called breathing secondary instability.
Marc Leonetti, Gwenn Boedec, Marc Jaeger. Breathing instability in biological cells, patterns of membrane proteins. Discontinuity, Nonlinearity, and Complexity, 2013, 2 (1), pp.75-84. ⟨10.5890/DNC.2012.12.001⟩. ⟨hal-00997680⟩
Journal: Discontinuity, Nonlinearity, and Complexity
Thomas Prusek, Edgar Moleiro, Fadila Oukacine, André Adobes, Marc Jaeger, et al.. Deposit models for tube support plate flow blockage in Steam Generators. Nuclear Engineering and Design, 2013, 262, pp.418-428. ⟨10.1016/j.nucengdes.2013.05.017⟩. ⟨hal-00997704⟩ Plus de détails...
Corrosion product deposits in the secondary side of nuclear power plant Steam Generators may result in Tube Support Plate flow blockage, and tube fouling. In order to simulate those two phenomena in the whole Steam Generator, a solid deposit growth model has been developed by the EDF R&D Division. This model is implemented in the frame of THYC, which is the EDF's reference code for the modeling of two-phase thermal-hydraulic phenomena at the subchannel scale. A new deposit process, based on Tube Support Plate flow blockage studies, has been developed and implemented in the model, and is presented in this work. It can be defined by two main steps: particle deposition, and strengthening process called "flashing" due to soluble species precipitation in the pores of the particle deposit. The relevance of this process is tested by comparing the simulation results to the actual levels of flow blockage observed in some nuclear plants. Two dominant trends are showed in this work: the flow blockage is more important on the hot leg than on the cold leg and at the top than at the bottom of the Steam Generators. Moreover the flow blockages at the upper Tube Support Plate have the special feature to be more important at the periphery than at the center. The "flashing" phenomenon allows one to underline the magnetite solubility dependence, so the pH dependence, of flow blockage phenomenon. A pH elevation of the secondary circuit seems to be a interesting remedy which is currently considered on EDF fleet.
Thomas Prusek, Edgar Moleiro, Fadila Oukacine, André Adobes, Marc Jaeger, et al.. Deposit models for tube support plate flow blockage in Steam Generators. Nuclear Engineering and Design, 2013, 262, pp.418-428. ⟨10.1016/j.nucengdes.2013.05.017⟩. ⟨hal-00997704⟩
T. Prusek, E. Moleiro, F. Oukacine, A. Adobes, Marc Jaeger, et al.. Deposit models for tube support plate flow blockage in Steam Generators. Nuclear Engineering and Design, 2013, 262, pp.418-428. ⟨10.1016/j.nucengdes.2013.05.017⟩. ⟨hal-00997704⟩ Plus de détails...
Corrosion product deposits in the secondary side of nuclear power plant Steam Generators may result in Tube Support Plate flow blockage, and tube fouling. In order to simulate those two phenomena in the whole Steam Generator, a solid deposit growth model has been developed by the EDF R&D Division. This model is implemented in the frame of THYC, which is the EDF's reference code for the modeling of two-phase thermal-hydraulic phenomena at the subchannel scale. A new deposit process, based on Tube Support Plate flow blockage studies, has been developed and implemented in the model, and is presented in this work. It can be defined by two main steps: particle deposition, and strengthening process called "flashing" due to soluble species precipitation in the pores of the particle deposit. The relevance of this process is tested by comparing the simulation results to the actual levels of flow blockage observed in some nuclear plants. Two dominant trends are showed in this work: the flow blockage is more important on the hot leg than on the cold leg and at the top than at the bottom of the Steam Generators. Moreover the flow blockages at the upper Tube Support Plate have the special feature to be more important at the periphery than at the center. The "flashing" phenomenon allows one to underline the magnetite solubility dependence, so the pH dependence, of flow blockage phenomenon. A pH elevation of the secondary circuit seems to be a interesting remedy which is currently considered on EDF fleet.
T. Prusek, E. Moleiro, F. Oukacine, A. Adobes, Marc Jaeger, et al.. Deposit models for tube support plate flow blockage in Steam Generators. Nuclear Engineering and Design, 2013, 262, pp.418-428. ⟨10.1016/j.nucengdes.2013.05.017⟩. ⟨hal-00997704⟩
Gwenn Boedec, Marc Jaeger, Marc Leonetti. Sedimentation-induced tether on a settling vesicle. Physical Review E : Statistical, Nonlinear, and Soft Matter Physics, 2013, 88, pp.010702. ⟨10.1103/PhysRevE.88.010702⟩. ⟨hal-00997686⟩ Plus de détails...
Destabilization of soft interfaces into thin cylindrical filaments under external stresses is ubiquitous and is generally the first step toward breakup. We show that such filaments, called tethers, emerge from a vesicle subjected to gravity. Contrary to the pendant drop experiment, we demonstrate that the bending rigidity, a specific membrane property of vesicles, ensures the tethers reach a stationary state. Moreover, unlike point-like force experiments, we show that the family of shapes is continuous.
Gwenn Boedec, Marc Jaeger, Marc Leonetti. Sedimentation-induced tether on a settling vesicle. Physical Review E : Statistical, Nonlinear, and Soft Matter Physics, 2013, 88, pp.010702. ⟨10.1103/PhysRevE.88.010702⟩. ⟨hal-00997686⟩
Journal: Physical Review E : Statistical, Nonlinear, and Soft Matter Physics
Gwenn Boedec, Marc Jaeger, Marc Leonetti. Settling of a vesicle in the limit of quasi-spherical shapes. Journal of Fluid Mechanics, 2012, 690, pp.227-261. ⟨10.1017/jfm.2011.427⟩. ⟨hal-00997678⟩ Plus de détails...
Vesicles are drops of radius of a few tens of micrometres bounded by an impermeable lipid membrane of approximately 4 nm thickness in a viscous fluid. The salient characteristics of such a deformable object are a membrane rigidity governed by flexion due to curvature energy and a two-dimensional membrane fluidity characterized by a local membrane incompressibility. This provides unique properties with strong constraints on the internal volume and membrane area. Yet, when subjected to external stresses, vesicles exhibit a large deformability. The deformation of a settling vesicle in an infinite flow is studied theoretically, assuming a quasispherical shape and expanding all variables of the problem onto spherical harmonics. The contribution of thermal fluctuations is neglected in this analysis. A system of equations describing the temporal evolution of the shape is derived with this formalism. The final shape and the settling velocity are then determined and depend on two dimensionless parameters: the Bond number and the excess area. This simultaneous study leads to three stationary shapes, an egg-like shape already observed in an analogous experimental configuration in the limit of weak flow magnitude (Chatkaew, Georgelin, Jaeger & Leonetti, Phys. Rev. Lett, 2009, vol. 103(24), 248103), a parachute-like shape and a non-trivial non-axisymmetrical shape. The final shape depends on the initial conditions: prolate or oblate vesicle and orientation compared with gravity. The analytical solution in the small deformation regime is compared with numerical results obtained with a three-dimensional code. A very good agreement between numerical and theoretical results is found.
Gwenn Boedec, Marc Jaeger, Marc Leonetti. Settling of a vesicle in the limit of quasi-spherical shapes. Journal of Fluid Mechanics, 2012, 690, pp.227-261. ⟨10.1017/jfm.2011.427⟩. ⟨hal-00997678⟩
Gwen Boedec, Marc Leonetti, Marc Jaeger. 3D vesicle dynamics simulations with a linearly triangulated surface. Journal of Computational Physics, 2011, 230 (4), pp.1020-1034. ⟨10.1016/j.jcp.2010.10.021⟩. ⟨hal-00717365⟩ Plus de détails...
Simulations of biomembranes have gained an increasing interest in the past years. specificities of these membranes propose new challenges for the numerics. In particular, vesicle dynamics are governed by bending forces as well as a surface incompressibility constraint. A method to compute the bending force density resultant onto piecewise linearly triangulated surface meshes is described. This method is coupled with a boundary element method solver for inner and outer fluids, to compute vesicle dynamics under external flows. The surface incompressibility constraint is satisfied by the construction of a projection operator.
Gwen Boedec, Marc Leonetti, Marc Jaeger. 3D vesicle dynamics simulations with a linearly triangulated surface. Journal of Computational Physics, 2011, 230 (4), pp.1020-1034. ⟨10.1016/j.jcp.2010.10.021⟩. ⟨hal-00717365⟩
Sunita Chatkaew, Marc Georgelin, Marc Jaeger, Marc Leonetti. Dynamics of Vesicle Unbinding under axisymmetric flow. Physical Review Letters, 2009, 103 (24), pp.248103. ⟨10.1103/PhysRevLett.103.248103⟩. ⟨hal-00440220⟩ Plus de détails...
Sunita Chatkaew, Marc Georgelin, Marc Jaeger, Marc Leonetti. Dynamics of Vesicle Unbinding under axisymmetric flow. Physical Review Letters, 2009, 103 (24), pp.248103. ⟨10.1103/PhysRevLett.103.248103⟩. ⟨hal-00440220⟩
M. Jaeger, M. Carin. The Front-Tracking ALE Method: Application to a Model of the Freezing of Cell Suspensions. Journal of Computational Physics, 2002, 179 (2), ⟨10.1006/jcph.2002.7084⟩. ⟨hal-01282007⟩ Plus de détails...
A new front-tracking method to compute discontinuous solutions on unstructured finite element meshes is presented. Using an arbitrary Lagrangian–Eulerian formula- tion, the mesh is continuously adapted by moving the nearest nodes to the interface. Thus, the solution is completely sharp at the interface and no smearing takes place. The dynamic node adjustment is confined to global nodes near the front, rendering remeshing unnecessary. The method has been applied to the osmotic motion of a two-dimensional cell arising from a concentration gradient generated by a moving solidification front. The engulfment of one cell by an advancing solidification front, which rejects the solutes in a binary salt solution, is then computed. The results indicate that the ice increases the solute gradient around the cell. Furthermore, the presence of the cell, which prevents diffusion of the solute, leads to large changes in the morphology of the ice front.
M. Jaeger, M. Carin. The Front-Tracking ALE Method: Application to a Model of the Freezing of Cell Suspensions. Journal of Computational Physics, 2002, 179 (2), ⟨10.1006/jcph.2002.7084⟩. ⟨hal-01282007⟩
M. Carin, M. Jaeger. Numerical simulation of the interaction of biological cells with an ice front during freezing. European Physical Journal: Applied Physics, 2001, 16 (3), ⟨10.1051/epjap:2001205⟩. ⟨hal-01282025⟩ Plus de détails...
The goal of this study is a better understanding of the interaction between cells and a solidi- fication front during a cryopreservation process. This technique of freezing is commonly used to conserve biological material for long periods at low temperatures. However the biophysical mechanisms of cell in- juries during freezing are difficult to understand because a cell is a very sophisticated microstructure interacting with its environment. We have developed a finite element model to simulate the response of cells to an advancing solidification front. A special front-tracking technique is used to compute the motion of the cell membrane and the ice front during freezing. The model solves the conductive heat transfer equation and the diffusion equation of a solute on a domain containing three phases: one or more cells, the extra-cellular solution and the growing ice. This solid phase growing from a binary salt solution rejects the solute in the liquid phase and increases the solute gradient around the cell. This induces the shrinkage of the cell. The model is used to simulate the engulfment of one cell modelling a red blood cell by an advancing solidification front initially planar or not is computed. We compare the incorporation of a cell with that of a solid particle.
M. Carin, M. Jaeger. Numerical simulation of the interaction of biological cells with an ice front during freezing. European Physical Journal: Applied Physics, 2001, 16 (3), ⟨10.1051/epjap:2001205⟩. ⟨hal-01282025⟩
Journal: European Physical Journal: Applied Physics
Iain Shepherd, Tim Haste, Naouma Kourti, Francesco Oriolo, Mario Leonardi, et al.. Investigation of core degradation (COBE). Nuclear Engineering and Design, 2001, 209 (1-3), ⟨10.1016/S0029-5493(01)00393-4⟩. ⟨hal-01282019⟩ Plus de détails...
The COBE project started in February 1996 and finished at the end of January 1999. The main objective was to improve understanding of core degradation behaviour during severe accidents through the development of computer codes, the carrying out of experiments and the assessment of the computer codes’ ability to reproduce experimental behaviour. A major effort was devoted to quenching behaviour and a substantial achievement of the project was the design and commissioning of a new facility for the simulation of quenching of intact fuel rods. Two tests, carefully scaled to represent realistic reactor conditions, were carried out in this facility and the hydrogen generated during the quenching process was measured using two independent measuring systems. The codes were able to reproduce the results in the first test, where little hydrogen was generated but not the second test, where the extra steam produced during quenching caused an invigorated Zircaloy oxidation and a substantial hydrogen generation. A number of smaller parametric experiments allowed detailed models to be developed for the absorption of hydrogen and the cracking of cladding during quenching. COBE also investigated other areas concerned with late-phase phenomena.
Iain Shepherd, Tim Haste, Naouma Kourti, Francesco Oriolo, Mario Leonardi, et al.. Investigation of core degradation (COBE). Nuclear Engineering and Design, 2001, 209 (1-3), ⟨10.1016/S0029-5493(01)00393-4⟩. ⟨hal-01282019⟩
Iain Shepherd, Tim Haste, Naouma Kourti, Francesco Oriolo, Mario Leonardi, et al.. Investigation of core degradation (COBE). Nuclear Engineering and Design, 2001, 209 (1-3), ⟨10.1016/S0029-5493(01)00393-4⟩. ⟨hal-01282019⟩ Plus de détails...
The COBE project started in February 1996 and finished at the end of January 1999. The main objective was to improve understanding of core degradation behaviour during severe accidents through the development of computer codes, the carrying out of experiments and the assessment of the computer codes’ ability to reproduce experimental behaviour. A major effort was devoted to quenching behaviour and a substantial achievement of the project was the design and commissioning of a new facility for the simulation of quenching of intact fuel rods. Two tests, carefully scaled to represent realistic reactor conditions, were carried out in this facility and the hydrogen generated during the quenching process was measured using two independent measuring systems. The codes were able to reproduce the results in the first test, where little hydrogen was generated but not the second test, where the extra steam produced during quenching caused an invigorated Zircaloy oxidation and a substantial hydrogen generation. A number of smaller parametric experiments allowed detailed models to be developed for the absorption of hydrogen and the cracking of cladding during quenching. COBE also investigated other areas concerned with late-phase phenomena.
Iain Shepherd, Tim Haste, Naouma Kourti, Francesco Oriolo, Mario Leonardi, et al.. Investigation of core degradation (COBE). Nuclear Engineering and Design, 2001, 209 (1-3), ⟨10.1016/S0029-5493(01)00393-4⟩. ⟨hal-01282019⟩
A Decarlis, Marc Jaeger. Effective thermal conductivity of heterogeneous two-phase material using the self-consistent finite element method. Scripta Materialia, 2001, 44 (8-9), ⟨10.1016/S1359-6462(01)00830-2⟩. ⟨hal-01282039⟩ Plus de détails...
Advanced materials often involve the mixture of a second phase material (the inclusions) in a host phase (the matrix). Indeed, materials with very specific properties can be synthesized by controlling the nature of each phase as well as the shape and spatial distribution of the inclusions. Therefore, homogenization tools yielding accurate effective transport properties are needed. We present a numerical extension of a pure analytical treatment of the problem, namely the self-consistent method.
A Decarlis, Marc Jaeger. Effective thermal conductivity of heterogeneous two-phase material using the self-consistent finite element method. Scripta Materialia, 2001, 44 (8-9), ⟨10.1016/S1359-6462(01)00830-2⟩. ⟨hal-01282039⟩
Eric Serre, Sandrine Hugues, Emilia Crespo del Arco, Anthony Randriamampianina, Patrick Bontoux. Axisymmetric and three-dimensional instabilities in an Ekman boundary layer flow. International Journal of Heat and Fluid Flow, 2001, 22 (1), pp.82-93. ⟨hal-01023080⟩ Plus de détails...
Eric Serre, Sandrine Hugues, Emilia Crespo del Arco, Anthony Randriamampianina, Patrick Bontoux. Axisymmetric and three-dimensional instabilities in an Ekman boundary layer flow. International Journal of Heat and Fluid Flow, 2001, 22 (1), pp.82-93. ⟨hal-01023080⟩
Journal: International Journal of Heat and Fluid Flow
Adnane Boukamel, Stéphane Méo, Olivier Débordes, Marc Jaeger. A thermo-viscoelastic model for elastomeric behaviour and its numerical application. Archive of Applied Mechanics, 2001, 71 (12), pp.785-801. ⟨10.1007/s004190100191⟩. ⟨hal-01236417⟩ Plus de détails...
This paper presents a model of thermo-mechanical behaviour of viscoelastic elastomers under large strain. A formulation is proposed with a generalisation to large strain of the Poynting–Thomson rheological model. A finite element formulation is then exposed taking the incompressibility constraint for mechanical equilibrium into account. On the thermomechanical coupling aspect, an algorithm of time discretisation is proposed with two time scales corresponding respectively to mechanical and thermal behaviours. Finally, an application for the simulation of a double-shearing test is presented with an analysis of parameters' influence and a comparison between numerical and experimental results.
Adnane Boukamel, Stéphane Méo, Olivier Débordes, Marc Jaeger. A thermo-viscoelastic model for elastomeric behaviour and its numerical application. Archive of Applied Mechanics, 2001, 71 (12), pp.785-801. ⟨10.1007/s004190100191⟩. ⟨hal-01236417⟩
A. Decarlis, M. Jaeger, Roland Martin. Determination of the Effective Thermal Conductivity Tensor of Heterogeneous Media Using a Self-Consistent Finite Element Method: Application to the Pseudo-percolation Thresholds of Mixtures Containing Nonspherical Inclusions. Journal of Heat Transfer, 2000, 122 (1), ⟨10.1115/1.521451⟩. ⟨hal-01282067⟩ Plus de détails...
This paper concerns the determination of the effective thermal conductivity of heterogeneous media with randomly dispersed inclusions. Inclusions of arbitrary shape can be considered since the self-consistent problem is solved numerically with the finite element method. Results for many different cases of heterogeneous media with axially symmetrical inclusions are presented. Moreover, the influence of the inclusion's shape on the pseudo-percolation threshold is investigated.
A. Decarlis, M. Jaeger, Roland Martin. Determination of the Effective Thermal Conductivity Tensor of Heterogeneous Media Using a Self-Consistent Finite Element Method: Application to the Pseudo-percolation Thresholds of Mixtures Containing Nonspherical Inclusions. Journal of Heat Transfer, 2000, 122 (1), ⟨10.1115/1.521451⟩. ⟨hal-01282067⟩
Marc Jaeger, Muriel Carin, Marc Medale, Gretar Tryggvason. The Osmotic Migration of Cells in a Solute Gradient. Biophysical Journal, 1999, 77 (3), ⟨10.1016/S0006-3495(99)76977-8⟩. ⟨hal-01282080⟩ Plus de détails...
The effect of a nonuniform solute concentration on the osmotic transport of water through the boundaries of a simple model cell is investigated. A system of two ordinary differential equations is derived for the motion of a single cell in the limit of a fast solute diffusion, and an analytic solution is obtained for one special case. A two-dimensional finite element model has been developed to simulate the more general case (finite diffusion rates, solute gradient induced by a solidification front). It is shown that the cell moves to regions of lower solute concentration due to the uneven flux of water through the cell boundaries. This mechanism has apparently not been discussed previously. The magnitude of this effect is small for red blood cells, the case in which all of the relevant parameters are known. We show, however, that it increases with cell size and membrane permeability, so this effect could be important for larger cells. The finite element model presented should also have other applications in the study of the response of cells to an osmotic stress and for the interaction of cells and solidification fronts. Such investigations are of major relevance for the optimization of cryopreservation processes.
Marc Jaeger, Muriel Carin, Marc Medale, Gretar Tryggvason. The Osmotic Migration of Cells in a Solute Gradient. Biophysical Journal, 1999, 77 (3), ⟨10.1016/S0006-3495(99)76977-8⟩. ⟨hal-01282080⟩
Médale Marc, Marc Jaeger, Ahmed Kaiss. Finite element analysis of the action of buoyancy-induced and thermocapillary flow on the melting of tin in a 2D square cavity. Computer Assisted Mechanics and Engineering Sciences, 1999. ⟨hal-01282058⟩ Plus de détails...
A finite element model has been developed for the computation of melting/solidifying process under the combined action of buoyancy and surface tension forces. Validated on the square cavity benchmark of Gobin and Le Quéré (Bertrand et al. [1], Gobin and Le Quéré [2]), the numerical model is used to extend this previous analysis to the free surface case where surface tension can drive the flow (capillary flow). A comparison of the results obtained for three types of boundary conditions applied at the top of the melting pool is performed. It shows that in the studied case of tin where the thermal Bond number is moderated (Bo=200), the flow is still mainly dominated by buoyancy effect as long as the melted pool is deep enough like in the square cavity case of the above mentioned benchmark.
Médale Marc, Marc Jaeger, Ahmed Kaiss. Finite element analysis of the action of buoyancy-induced and thermocapillary flow on the melting of tin in a 2D square cavity. Computer Assisted Mechanics and Engineering Sciences, 1999. ⟨hal-01282058⟩
Journal: Computer Assisted Mechanics and Engineering Sciences
