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Research

2 thematic axes, 6 research teams, 2 sites

The originality of M2P2 lies in its research themes in the fields of Computational Fluid Mechanics and Chemical Engineering. Research in mechanics and modeling is associated with a strong methodological development around calculation codes for the simulation of natural and industrial flows. In the field of process engineering, the research concerns the development of innovative processes as well as the study of the problems involved in these processes within the framework of a strong contractual activity.
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6 research teams, 2 sites

+ Technopôle Château Gombert
+ Technopôle Arbois

Publications

  • 2024
    Aymeric Fabien, Guillaume Lefebvre, Elisabeth Badens, Brice Calvignac, Damien Chaudanson, et al.. Contact angle of ethanol, water, and their mixtures on stainless steel surfaces in dense carbon dioxide. Journal of Colloid and Interface Science, 2024, 655, pp.535-545. ⟨10.1016/j.jcis.2023.10.163⟩. ⟨hal-04316090⟩ Plus de détails...

    Contact angle of ethanol, water, and their mixtures on stainless steel surfaces in dense carbon dioxide

    Hypothesis Contact angle can be a key parameter in chemical engineering. However, the development and the optimization of numerous processes using supercritical CO2, considered as environmentally friendly, requires new measurements under dense CO2 atmosphere. Besides, the influence of the roughness or the wetting regime on the contact angle is known at ambient conditions but remains to be discussed for systems under high pressure. Experimental Contact angle measurements of ethanol, water, and their mixtures, with ethanol mass fractions ranging from 0.25 to 0.75, on two stainless steels in saturated CO2 at pressures ranging from 0.1 MPa to 15.1 MPa, and at 313 K and 333 K were carried out in a set-up improving mass transfer between the studied liquid and the continuous fluid phase. Stainless steel surfaces have been characterized by atomic force and scanning electron microscopies allowing the application of the Wenzel equation. Findings Ethanol wetted totally both stainless steels while contact angles of all other liquids were increased by the rise of pressure, with contact angles up to 128 ° for water at 15.1 MPa. Trapped bubbles were observed at the solid/liquid interface and the bubble formation is discussed. Furthermore, the potential influence of bubble presence on the wetting regime is prospected through the question: could the pressure rise modify the wetting regime?
    Aymeric Fabien, Guillaume Lefebvre, Elisabeth Badens, Brice Calvignac, Damien Chaudanson, et al.. Contact angle of ethanol, water, and their mixtures on stainless steel surfaces in dense carbon dioxide. Journal of Colloid and Interface Science, 2024, 655, pp.535-545. ⟨10.1016/j.jcis.2023.10.163⟩. ⟨hal-04316090⟩
    Journal: Journal of Colloid and Interface Science
    Date de publication: 01-02-2024
    Auteurs:
    Liste des documents:
    Digital object identifier (doi): http://dx.doi.org/10.1016/j.jcis.2023.10.163
    Voir la publication sur Hal
  • 2023
    Vénicia Numa, Christelle Crampon, Arnaud Bellon, Adil Mouahid, Elisabeth Badens. Valorization of food side streams by supercritical fluid extraction of compounds of interest from apple pomace. Journal of Supercritical Fluids, 2023, 202, pp.106056. ⟨10.1016/j.supflu.2023.106056⟩. ⟨hal-04294235⟩ Plus de détails...

    Valorization of food side streams by supercritical fluid extraction of compounds of interest from apple pomace

    Supercritical CO2 (scCO2) extraction, a green technology still little applied to side streams, has been used to explore the potential recovery of beneficial compounds from apple pomace, a food industry byproduct. The study examines the potential of scCO2 extraction on freeze-dried and airflow dried apple pomace, using laboratory-scale equipment with varying pressures (200–400 bar), temperatures (35–55 °C) with a fixed CO2 flow rate. Extracts were analyzed through LC-MS and GC-MS, while antioxidant capacity was assessed using the ABTS assay. The results were compared to those from Soxhlet n-hexane extraction. Optimal conditions of 300 bar and 55 °C with freeze-dried apple pomace yielded the highest mass loss. The main compounds identified included glyceryl dilinoleate, linoleic acid, and diacyl glycerol, with significant ursolic acid content. A preliminary higher scale feasibility test under optimal conditions demonstrated promising, duplicable outcomes, supporting prior claim that apple pomace contains valuable ingredients that can be reused in various industrial sectors.
    Vénicia Numa, Christelle Crampon, Arnaud Bellon, Adil Mouahid, Elisabeth Badens. Valorization of food side streams by supercritical fluid extraction of compounds of interest from apple pomace. Journal of Supercritical Fluids, 2023, 202, pp.106056. ⟨10.1016/j.supflu.2023.106056⟩. ⟨hal-04294235⟩
    Journal: Journal of Supercritical Fluids
    Date de publication: 01-11-2023
    Auteurs:
    Digital object identifier (doi): http://dx.doi.org/10.1016/j.supflu.2023.106056
    Voir la publication sur Hal
  • 2023
    J. Yang, A. Mouilleron, M. Monnot, C. Cordier, P. Moulin. Ultrafiltration for the biosecurity of fish production: The case of a sturgeon nursery. Aquacultural Engineering, 2023, 103, pp.102366. ⟨10.1016/j.aquaeng.2023.102366⟩. ⟨hal-04202096⟩ Plus de détails...

    Ultrafiltration for the biosecurity of fish production: The case of a sturgeon nursery

    J. Yang, A. Mouilleron, M. Monnot, C. Cordier, P. Moulin. Ultrafiltration for the biosecurity of fish production: The case of a sturgeon nursery. Aquacultural Engineering, 2023, 103, pp.102366. ⟨10.1016/j.aquaeng.2023.102366⟩. ⟨hal-04202096⟩
    Journal: Aquacultural Engineering
    Date de publication: 01-11-2023
    Auteurs:
    Digital object identifier (doi): http://dx.doi.org/10.1016/j.aquaeng.2023.102366
    Voir la publication sur Hal
  • 2023
    Emilie Gout, Fatimatou Toure Lo, Mathias Monnot, Olivier Boutin, Pierre Vanloot, et al.. Coupling membrane processes with wet air oxidation for the remediation of industrial effluents. Chemical Engineering Journal, 2023, 472, pp.144937. ⟨10.1016/j.cej.2023.144937⟩. ⟨hal-04202142⟩ Plus de détails...

    Coupling membrane processes with wet air oxidation for the remediation of industrial effluents

    Emilie Gout, Fatimatou Toure Lo, Mathias Monnot, Olivier Boutin, Pierre Vanloot, et al.. Coupling membrane processes with wet air oxidation for the remediation of industrial effluents. Chemical Engineering Journal, 2023, 472, pp.144937. ⟨10.1016/j.cej.2023.144937⟩. ⟨hal-04202142⟩
    Journal: Chemical Engineering Journal
    Date de publication: 01-09-2023
    Auteurs:
    Digital object identifier (doi): http://dx.doi.org/10.1016/j.cej.2023.144937
    Voir la publication sur Hal
  • 2023
    Mathis Pasquier, Stéphane Jay, Jérôme Jacob, Pierre Sagaut. A Lattice-Boltzmann-Based Modelling Chain for Traffic-Related Atmospheric Pollutant Dispersion at the Local Urban Scale. Building and Environment, 2023, 242, pp.110562. ⟨10.1016/j.buildenv.2023.110562⟩. ⟨hal-04190005⟩ Plus de détails...

    A Lattice-Boltzmann-Based Modelling Chain for Traffic-Related Atmospheric Pollutant Dispersion at the Local Urban Scale

    Urban traffic-related air pollution is a major source of environmental and health damage and is difficult to quantify due to its inherent physical complexity. We construct a CFD-based simulation framework coupling an efficient numerical method for turbulent fluid flows with a microscopic traffic model and an emissions model to simulate road transport pollutant dispersion at the urban microscale. We improve the open-source Lattice-Boltzmann based CFD software OpenLB to overcome its original stability deficiencies for high Reynolds number flows. A stable recursive regularization procedure with a double distribution function approach is proposed to solve an advection diffusion equation for passive scalar transport at high Reynolds number. The code is successfully validated on three reference cases of increasing complexity and the traffic model SUMO along with a physical engine emissions model are coupled with OpenLB to simulate traffic-induced pollution from a road network in a realistic complex geometry. Transient flow features are analysed and the time-averaged concentration levels in different neighbourhoods of the considered geometry are evaluated: high concentration levels are observed close to the streets but also inside specific building infrastructures due to complex wind dynamics. Analyses of altitudinal concentration variations show that flow recirculations located close to traffic lights can drive pollutant over the buildings and increase concentration levels inside inner courtyards. Time-averaged concentration maps are constructed using both spatially uniform and non-uniform line sources and it is shown that using uniform sources leads to up to 20% local concentration overestimations inside the urban canopy.
    Mathis Pasquier, Stéphane Jay, Jérôme Jacob, Pierre Sagaut. A Lattice-Boltzmann-Based Modelling Chain for Traffic-Related Atmospheric Pollutant Dispersion at the Local Urban Scale. Building and Environment, 2023, 242, pp.110562. ⟨10.1016/j.buildenv.2023.110562⟩. ⟨hal-04190005⟩
    Journal: Building and Environment
    Date de publication: 15-08-2023
    Auteurs:
    Liste des documents:
    Digital object identifier (doi): http://dx.doi.org/10.1016/j.buildenv.2023.110562
    Voir la publication sur Hal
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All lab's publications

Actualités scientifiques

Actualités
11 décembre 2023 - Modeling and analysis of the dynamics of viscoelastic fluids undergoing oscillatory forcing: application to mucus clearance / PhD Defense Amirhosein Nosrat Kharazmi
Doctorant : Amirhosein Nosrat Kharazmi  
Date : le lundi 11 décembre 2023 à 14h00 /  Centrale Méditerranée, Plot 6, Amphi n°3

Abstract :  Viscoelastic fluids are ubiquitous in the human body and more generally in nature, and their study offers numerous applications across various industrial sectors, including the health, biomedical, and pharmacy industries. They function as non-Newtonian fluids in several living system structures, including the human cardiovascular-pulmonary network, blood, and mucus, displaying both viscous and elastic characteristics. Due to their complex behavior, simulating numerically the dynamics of these fluids remains challenging because of the non-linear character of the equations and the associated numerical instabilities. In this work, a viscoelastic flow undergoing an unsteady forcing is simulated numerically by solving the momentum equations coupled to a constitutive equation for the fluid, namely the Oldroyd-B model. In this model, polymer molecules are considered as two beads connected by a spring and surrounded by a viscous fluid. To overcome the numerical instabilities arising from high elasticity effects, a hybrid lattice Boltzmann-finite difference method is proposed to solve viscous and elastic parts, respectively. The numerical approach is validated on several numerical benchmark test cases, including the Taylor green vortex, two-dimensional Poiseuille flow, and two-dimensional flow past a cylinder. The results present a good agreement with analytical solutions and literature reference data. A physical analysis of the dynamics of forced viscoelastic fluid flows is performed in the context of mucus clearance in the human respiratory system. The results show that the highest flow rate of mucus can be achieved in cases of resonance, i.e., when the frequency of the Womersley flow matches the natural frequency of the viscoelastic fluid. An increase in elasticity is found to lead to a higher mean flow rate in the case of viscoelastic shear-thinning fluids, while for Newtonian viscoelastic fluids, the mean flow is independent of elasticity. On the other hand, the flow rate decreases by adding yield stress to elasto-viscoplastic fluid. These results are meaningful in the context of biomedical devices improving mucociliary clearance of bronchial mucus. Keywords: lattice-Boltzmann method, viscoelastic fluid, Oldroyd-B equation, non-Newtonian flow, mucus, periodic forcing, bronchial clearance.

Jury

Directeur de these  M. Julien FAVIER  Aix Marseille Université

CoDirecteur de these  M. Umberto D'ORTONA  CNRS / Aix Marseille Université

Examinateur  Mme Isabelle CHEYLAN  Aix Marseille Université

Président  M. Alistair REVELL  University of Manchester

Rapporteur  M. Hugues BODIGUEL  Laboratoire Rhéologie et Procédés, Université Grenoble Alpes-Grenoble INP,

Rapporteur  M. Gonçalo SILVA  University of Évora

1 décembre 2023 - Heavy ions migration in tokamak boundary plasmas : development of a numerical model to interpret WEST experiments / PhD Defense Stefano Di Genova
Doctorant : Stefano Di Genova   
Date : le vendredi 1er décembre 2023 à 14h00 /  CEA-Cadarache, bâtiment 506, Cadarache, 13108, Saint-Paul-lez-Durance / Salle René Gravier 

Abstract :  Tungsten (W) is considered to be the most suitable material for the Plasma-Facing Components (PFCs) of future tokamak fusion reactors. Nonetheless, the deployment of this material in tokamak experiments has been shown to be detrimental to plasma discharges: W is eroded from the wall and contaminates the plasma, causing large power losses through radiation. Plasma operations in the W Environment Steady-state Tokamak (WEST) are heavily influenced by W contamination. In WEST discharges, the power loss due to W contamination is, on average, around 50% of the total power injected into the plasma. Moreover, the radiated power fraction is insensitive to plasma conditions. The causes behind this experimental trend are not fully understood. Furthermore, in experiments, it is not possible to detect which eroded PFCs impact the plasma W content the most. For these reasons, the experimental analysis of W contamination in WEST must be supported by modelling activities. The modeling of W migration in WEST helps estimate the W screening at the different PFCs and analyse the contamination trends in the tokamak. During this Ph.D. thesis, two well-established numerical tools (SOLEDGE and ERO2.0) are used to model the boundary plasma and the W migration in WEST plasma discharges. Based on simulations, a close analysis of the erosion of each WEST PFC and its impact on the plasma W content is performed. Results show that the WEST lower divertor is the most eroded PFC, but it is also the most screened one. On the other hand, less eroded components could impact the plasma W content more than the lower divertor. The tokamak upper divertor, the external surface of the baffle, and the antenna protections might be unscreened enough to influence the plasma W content even at low erosion rates. The research activity focuses on the antennas: 3D simulations of the boundary plasma are carried out using a complex wall geometry, the 3D wall is equipped with toroidally localized objects representing WEST antennas. The antenna protections are weakly screened, and the impact of their erosion on the plasma W content is predominant over the other PFCs one. The 3D model is used to analyze W migration over the WEST operational domain. The WEST database is sampled to obtain a scan of simulation input parameters that mimic the WEST plasma conditions over an experimental campaign. The simulation results are compared to WEST diagnostics data (reflectometry, Langmuir probes, and visible spectroscopy) to verify that the simulated plasma conditions are compatible with the WEST database. The W migration trend is analysed: the W density increases proportionally with the power entering the scrape-off layer and strongly drops when the radial distance between the separatrix and the antennas (Radial Outer Gap, ROG) increases. The radiated power is estimated in simulations with a simple 0D model. At a given ROG, the radiated power is proportional to the total injected power, with the radiated fraction which is not sensitive to plasma conditions. These trends are qualitatively and, at times, quasi-quantitatively comparable to what is observed in WEST experiments. In simulations, the radiated fraction is insensitivity to plasma conditions is related to the low screened W influx caused by the erosion of the antenna protections. This research activity shows how simplified numerical simulations of the boundary plasma and W migration can give a realistic picture of the W migration trends in tokamak experiments. The results also underline the importance of the main chamber PFCs located close to the confined plasma. Finally, this work points out how the net W influx coming from low screened PFCs might be weakly affected by plasma conditions and how it might become challenging to control during plasma discharges.

Jury

Directeur de these  M. Eric SERRE  M2P2, CNRS, Centrale Méditerranée, Aix Marseille Université

Président  M. Khaled HASSOUNI  LSPM, CNRS-UPR 3407, Université Paris 13

Rapporteur  M. Karl KRIEGER  Max-Planck-Institut für Plasmaphysik

Rapporteur  M. David DONOVAN  University of Tennessee Knoxville

Examinateur  Mme Emmanuelle TSITRONE  IRFM, CEA-Cadarache

Examinateur  M. Paolo INNOCENTE  Consorzio RFX

Examinateur  M. Sebastijan BREZINSEK  IEK-4 Forschungszentrum Jülich et Universität Düsseldorf

CoDirecteur de these  M. Guido CIRAOLO  IRFM, CEA-Cadarache 

28 novembre 2023 - Exploring Membrane Dynamics through Continuous Media Mechanical Modelling : Insights into Red Blood Cells and T Cell Activation / PhD Defense Varun Puthumana

Doctorant : Varun PUTHUMANA

Date : le mardi 28 novembre 2023 à 14h00 / Amphithéâtre du LMA

Abstract : The lipid bilayer forms the dynamic boundary of cells, while the cytoskeleton provides structural support which is connected to the bilayer through protein junction complexes. Classically, these two structures are often modelled as a single entity for computational simplicity, neglecting the fact that they slide in relation to each other. We develop a realistic representation that accurately depicts the bilayer-cytoskeleton structure which is validated using red blood cells (RBC), by carefully analysing its dynamics in flow. Moreover, as the study progresses, this will be extended to investigate the activation of T cells by the coordinated actions of the cytoskeleton and condensation of the T cell receptor (TCR). 
Through comprehensive computational assessments of various modelling strategies by analyzing RBC behaviour in different flow scenarios, including extensional and shear flows, we explore the efficacy of double-layer strategies, such as the vesicle-capsule and capsule-capsule models, in accounting for the fluidity and surface incompressibility of the lipid bilayer. The double-layer capsule-capsule model is then employed to examine the localized reorganization of the cytoskeleton within T cells which subsequently resorb microvilli and triggers cell activation through the condensation of TCRs. The developed T cell model faithfully replicates the behaviour of an entire T cell during its interaction with an antigen-presenting cell. Our work illuminates the significance of establishing a region with a spontaneous actin deficit to facilitate seamless contact with the T cell, thereby enabling TCR condensation within a specific zone. The dynamic interplay between actin depolymerization and TCR condensation emerges as a pivotal factor in the process of T cell activation. Our findings indicate that the cell's geometry and cytoskeleton depolymerisation together initiate condensation at the tip of microvilli. Additionally, our investigations delve into the role of surface tension in instigating the formation of condensates at the immune synapse.
Our findings also reveal relevant information about the membrane dynamics such that introducing sliding between the layers provides the cytoskeleton with a significant degree of freedom to relax its elastic stresses, resulting in a substantial increase in RBC elongation. Moreover, our research demonstrates that the choice of membrane modelling strategy for RBCs has a more profound impact on their behaviour than the selection of the cytoskeleton's reference shape. These results underscore the importance of not solely considering mechanical properties but also emphasize the necessity of integrating these properties thoughtfully in computational models. Interestingly, our study uncovers a novel indicator for determining the appropriate stress-free shape of the RBC cytoskeleton, contributing to a deeper understanding of its biomechanics and offering valuable insights for future modelling efforts in the field.

Jury

Chaouqi MISBAH, LIPhy, Université Grenoble Alpes, Rapporteur 

Simon MENDEZ, IMAG, Université de Montpellier, Rapporteur 

Nicolas DESTAINVILLE, LPT, Université Toulouse III-Paul Sabatier, Examinateur 

Kheya SENGUPTA, CINaM, Aix-Marseille Université, Présidente 

Rémi LASSERRE, CIML, Aix-Marseille Université, CoDirection de thèse 

Marc JAEGER, M2P2, Aix-Marseille Université, Direction de thèse

24 novembre 2023 - Etude exploratoire pour l’évaluation du potentiel de technologies d’extraction vertes (ScCO2 et liquides pressurisés) pour la valorisation du marc de pomme dans le secteur cosmétique / Soutenance de thèse Venicia Numa

Doctorant : Venicia NUMA

Date : le  vendredi 24 Novembre 2023 à 09h30 à l'amphithéâtre du CEREGE.

Résumé : Cette étude explore le potentiel prometteur du marc de pomme comme source de composés pour l'industrie cosmétique. Des techniques d'extraction vertes, notamment le CO2 supercritique et les liquides pressurisés, sont utilisées pour optimiser l'ensemble du procédé de traitement/valorisation de sous-produits de l’industrie agroalimentaire, du laboratoire à l'échelle pilote. L'objectif principal est d'améliorer l'efficacité de l'extraction des composés d’intérêt du marc de pomme, tels que les polyphénols, les acides gras, les alcools gras et les esters. 
Tout d'abord, la séparation des composés du marc de pomme a été effectuée par extraction avec le ScCO2, à l'échelle laboratoire, sur une gamme de pression allant de 200 à 400 bar et une gamme de température variant de 35 à 55°C, à partir d’une biomasse lyophilisée. Les conditions optimales pour une perte en masse maximale lors de l'extraction et une capacité antioxydante intéressante ont été trouvées à 300 bar et 55°C, avec un rapport CO2/biomasse à 50. La composition des extraits a montré la présence d’un mélange de cires composé d'alcanes, d’acides gras, d’alcools gras, d’acides triterpéniques ou encore d’esters. Certains des acides triterpéniques détectés ont été quantifiés (pour l'acide ursolique), bien qu'en quantités et variétés plus faibles que prévu.
Les extractions ScCO2 réalisées à échelle semi-pilote (2L) et pilote (25L) garantissent une cohérence et une reproductibilité pour les applications industrielles. De l'échelle du laboratoire à l'échelle pilote, un rapport solvant/biomasse de 50 a été maintenu. Les quantités d'extrait obtenues étaient comparables (échelle laboratoire et semi-pilote), ainsi que pour les compositions d'extrait (laboratoire et pilote). L'objectif de cette extraction à plus grande échelle était de faciliter la potentielle industrialisation du procédé chez Symrise, fournissant une base pour les futurs travaux en vue d’une valorisation. 
Enfin, l'étude souligne l'importance de la transition vers une économie circulaire pour une intégration industrielle de procédés durables à long terme. Une estimation des coûts de l’extraction ScCO2 à grande échelle suggère un coût par kg de produit inversement proportionnel aux volumes traités rendant la valorisation avec le ScCO2 économiquement viable. Cette étude réalisée sur le marc de pomme ne permet pas de conclure sur une valorisation possible des extraits en tant qu’actifs cosmétiques à ce stade. Cependant, une valorisation des cires serait envisageable chez Symrise en tant qu’ingrédients fonctionnels. Cette étude offre des perspectives intéressantes pour une valorisation durable, abordant les défis environnementaux et mettant l’accent sur la nécessité d’un futur plus vert dans l'industrie cosmétique. 

Mots-clés : valorisation des drèches de pommes, fluides supercritiques, liquides sous pression, montée en échelle, technologies vertes 

Jury

Professeure Sagrario BELTRAN (Université de Burgos) - Rapporteuse

Professeur Nabil GRIMI (UTC Compiègne)- Rapporteur et président de jury

Docteur Grégory CHATEL (Université Savoie Mont Blanc) - Examinateur

Docteur Vincent PERRUT (Ateliers Fluides Supercritiques) - Examinateur

Professeure Elisabeth BADENS (Aix-Marseille Université) - Directrice de thèse

Professeure Christelle CRAMPON (Aix-Marseille Université) - Co-Directrice de thèse

Docteur Marielle LE MAIRE (Symrise) - Invitée

16 octobre 2023 - Simulation numérique d'émulsions microfluidiques à l'aide du Méthode Boltzmann sur réseau / Soutenance de thèse Gang Wang

Doctorant : Gang WANG

Date :  le lundi 16 octobre 2023 à 14h30 / Amphithéâtre 2 Centrale Méditerranée

Résumé : L'émulsification microfluidique est devenue une méthode populaire pour générer des gouttelettes de tailles et de distributions contrôlées. Cependant, en raison des limitations expérimentales, des outils numériques sont généralement utilisés pour fournir une compréhension approfondie des mécanismes sous-jacents et des effets complexes des écoulements microfluidiques. Cette thèse se concentre sur trois problématiques majeures qui émergent dans la simulation des émulsions microfluidiques en utilisant le modèle multicomposant pseudopotentiel de Boltzmann sur réseau, et sur l'application de méthodes améliorées pour réaliser des simulations microfluidiques. Ces trois problématiques sont la condition de mouillage des parois courbes (puisque de nombreux dispositifs microfluidiques ont des géométries de canaux complexes), la coalescence des gouttelettes dans les émulsions très concentrées, et la condition de sortie permettant aux gouttelettes de quitter le domaine de calcul en douceur.  Actuellement, comme dans la plupart des travaux précédents, la méthode simple de rebond (bounce-back, BB), associée à une interaction d'adhésion fluide-solide, est utilisée pour simuler les angles de contact. Cette méthode est précise pour une paroi droite. Cependant, lorsqu'il s'agit de parois courbes ou complexes, elle n'est pas assez précise car la paroi BB est seulement une approximation en escalier. Nous proposons donc d'étendre la méthode partiellement saturée (partially saturated method, PSM), une méthode précise du second ordre pour les conditions de paroi courbe conçue pour les écoulements monophasiques, aux écoulements multicomposants. La méthode proposée conserve exactement la masse et surpasse la méthode BB en termes de modélisation de l'angle de contact statique et de la fluidité du mouvement d'une gouttelette mouillant des parois courbes.  L'objectif principal de l'émulsion microfluidique est de produire rapidement des micro-gouttelettes de la taille souhaitée, ce qui conduit à des cristaux fluides mous, où les gouttelettes sont fortement concentrées et en contact étroit les unes avec les autres. Expérimentalement, l'ajout d'un agent tensioactif est nécessaire pour éviter que ces gouttelettes très serrées ne fusionnent. Numériquement, les gouttelettes en contact coalescent naturellement lorsque le modèle de pseudopotentiel original est appliqué en raison de l'absence de force répulsive aux interfaces de gouttelette en contact. Nous proposons une méthode simple pour introduire une répulsion aux interface de contact, le but étant d'imiter l'effet des agents tensionactifs. Nous constatons que cette méthode proposée est capable de modéliser des suspensions stables et fluides hautement concentrées, et de reproduire les cristaux fluides mous obtenus dans les expériences.  Dans les simulations microfluidiques, les microcanaux sont généralement tronqués pour des longueurs réduites, ce qui pose un problème aux sorties car les gouttelettes et les phases continues sortent simultanement. Pour permettre aux gouttelettes de quitter le domaine de simulation en douceur, nous appliquons une condition de limite de vitesse améliorée (velocity boundary condition, VBC), basée sur la méthode BB pour une paroi mobile, à la sortie. De plus, deux couches de nœuds fantômes sont mises à jour pour calculer les interactions de pseudopotentiel à la sortie. Avec cette méthode, les gouttelettes peuvent quitter les microcanaux en douceur sans distorsions significatives. À l'aide de ces méthodes améliorées, des simulations d'émulsions microfluidiques dans des canaux de focalisation de flux ont été réalisées, fournissant des aperçus précieux du comportement des gouttelettes dans de tels systèmes.

Jury


Joelle AUBIN (Université de Toulouse), Rapporteure

Florian DE VUYST (Université de Technologie de Compiègne), Rapporteur

Harry VAN DEN AKKER (Université de Limerick), Examinateur

Agnès MONTILLET (Université de Nantes), Président du jury

Pierrette GUICHARDON (Centrale Méditerranée), Directrice de thèse

Umberto D'ORTONA (Université d'Aix-Marseille), Co-Directeur de thèse

Jiupeng DU (Centrale Méditerranée), Invité


All PhD defenses