https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Tue, 16 Jun 2026 00:14:46 GMT 2026-06-16T00:14:46Z http://hdl.handle.net/10985/9753 In vitro cartilage culture: flow, transport and reaction in fibrous porous media AHMADI-SENICHAULT, Azita; LASSEUX, Didier; LETELLIER, Samuel Flow and transport in fibrous media are encountered in a wide variety of domains ranging from biotechnology to filtration in chemical engineering. The context of this work is the in vitro cartilage cell culture on a fibrous biodegradable polymer scaffold placed in a bioreactor. A seeding process using a liquid containing cells (chondrocytes) initiates the culture and an imposed continuous flow through the scaffold allows both the transport of nutrients necessary for cell-growth and of metabolic waste products. This work will attempt to contribute to the study of the hydrodynamics and transport through the fibrous scaffold at different stages of growth, both having a key role in the process of cell growth and on the final quality of the cultured cartilage. The hydrodynamics in the scaffold and in particular the relationship between macroscopic experimentally accessible properties such as the permeability and the porosity have first been studied. For this purpose, the formalism of volume averaging is employed and the associated closure problem is solved numerically with an artificial compressibility algorithm on the basis of a finite volume scheme on a Marker and Cell type of grid. Fibrous media with different microscopic structures are studied. Through a theoretical study, assuming local mass equilibrium, a macroscopic one-equation model describing the reactive transport (advection/diffusion/reaction) of the two species in a three-phase system composed of the cell-phase, a fluid phase and a solid phase is proposed. The volume averaging method is used to develop macroscopic transport equations and associated closure problems. Resolution of the latter over a unit cell representative of a pseudo-periodic medium allows the determination of effective macroscopic properties without any adjustable parameters. The dimensionless form of the closure problems involving advective, diffusive and reactive terms are numerically solved for any 3D geometrical configuration using a finite volume formulation using appropriate schemes. The velocity field input to the model is obtained by the resolution of the Navier-Stokes problem using a modified QUICK scheme and an Artificial Compressibility algorithm. The numerical tool is then validated by comparing its results to those presented in the literature for 2-D unit cells and under-classes of our model (namely, diffusion, diffusion/reaction and diffusion/advection problems). The complete problem involving convection, diffusion and reaction in the three phase system is then studied for different parameters. More precisely, the influence of a cell Peclet number and the solid and cell volume fractions on the dispersion tensor has been studied. Mon, 01 Jan 2007 00:00:00 GMT http://hdl.handle.net/10985/9753 2007-01-01T00:00:00Z AHMADI-SENICHAULT, Azita LASSEUX, Didier LETELLIER, Samuel Flow and transport in fibrous media are encountered in a wide variety of domains ranging from biotechnology to filtration in chemical engineering. The context of this work is the in vitro cartilage cell culture on a fibrous biodegradable polymer scaffold placed in a bioreactor. A seeding process using a liquid containing cells (chondrocytes) initiates the culture and an imposed continuous flow through the scaffold allows both the transport of nutrients necessary for cell-growth and of metabolic waste products. This work will attempt to contribute to the study of the hydrodynamics and transport through the fibrous scaffold at different stages of growth, both having a key role in the process of cell growth and on the final quality of the cultured cartilage. The hydrodynamics in the scaffold and in particular the relationship between macroscopic experimentally accessible properties such as the permeability and the porosity have first been studied. For this purpose, the formalism of volume averaging is employed and the associated closure problem is solved numerically with an artificial compressibility algorithm on the basis of a finite volume scheme on a Marker and Cell type of grid. Fibrous media with different microscopic structures are studied. Through a theoretical study, assuming local mass equilibrium, a macroscopic one-equation model describing the reactive transport (advection/diffusion/reaction) of the two species in a three-phase system composed of the cell-phase, a fluid phase and a solid phase is proposed. The volume averaging method is used to develop macroscopic transport equations and associated closure problems. Resolution of the latter over a unit cell representative of a pseudo-periodic medium allows the determination of effective macroscopic properties without any adjustable parameters. The dimensionless form of the closure problems involving advective, diffusive and reactive terms are numerically solved for any 3D geometrical configuration using a finite volume formulation using appropriate schemes. The velocity field input to the model is obtained by the resolution of the Navier-Stokes problem using a modified QUICK scheme and an Artificial Compressibility algorithm. The numerical tool is then validated by comparing its results to those presented in the literature for 2-D unit cells and under-classes of our model (namely, diffusion, diffusion/reaction and diffusion/advection problems). The complete problem involving convection, diffusion and reaction in the three phase system is then studied for different parameters. More precisely, the influence of a cell Peclet number and the solid and cell volume fractions on the dispersion tensor has been studied. http://hdl.handle.net/10985/10034 Transport of species in a fibrous media during tissue growth LETELLIER, Samuel; LASSEUX, Didier; AHMADI-SENICHAULT, Azita Tissue engineering is of major importance in biomedical transplantation techniques. However, some questions subsist as for example the mass transport between each pahse (cell, fluide and solid). In a previous paper, a one-equation model was developed in order to model mass transport during in vitro tissue growth using the volume averaging method. Using a dimensionless form of the model and a convenient formulation of the effective dispersion tensor, a numerical resolution of the closure problem is proposed. Some results allowing to validate the numerical tool are presented. This validation is carried out using results available in the literature for 2-D unit cells and under-classes of our model (namely diffusion, diffusion/reaction and diffusion/advection problems). Finally, we provide some results for the complete model taking into account diffusion, reaction and advection in the three phase system. Mon, 01 Jan 2007 00:00:00 GMT http://hdl.handle.net/10985/10034 2007-01-01T00:00:00Z LETELLIER, Samuel LASSEUX, Didier AHMADI-SENICHAULT, Azita Tissue engineering is of major importance in biomedical transplantation techniques. However, some questions subsist as for example the mass transport between each pahse (cell, fluide and solid). In a previous paper, a one-equation model was developed in order to model mass transport during in vitro tissue growth using the volume averaging method. Using a dimensionless form of the model and a convenient formulation of the effective dispersion tensor, a numerical resolution of the closure problem is proposed. Some results allowing to validate the numerical tool are presented. This validation is carried out using results available in the literature for 2-D unit cells and under-classes of our model (namely diffusion, diffusion/reaction and diffusion/advection problems). Finally, we provide some results for the complete model taking into account diffusion, reaction and advection in the three phase system. http://hdl.handle.net/10985/9983 In-vitro cartilage growth: macroscopic mass transport modelling in a three-phase system LETELLIER, Samuel; AHMADI-SENICHAULT, Azita; LASSEUX, Didier Transplantation of engineered tissues is of major interest as an alternative to autogenic alogenic or exogenic grafts. In this study, in vitro cartilage cell culture on a fibrous biodegradable polymer scaffold is under concern. The scaffold is first seeded with cells which adhere to the fibres and the system is then grown in a bioreactor. As reported in the literature, hydrodynamics and transport of nutrients and metabolic products during this growth process is of considerable importance, motivating our analysis. A one-equation macroscopic model was first developed in order to describe macroscopic mass transport during in vitro tissue growth using the volume averaging method. This model takes into account a three phase system composed of solid fibres, cell phase and fluid phase and allows determination of the macroscopic quantities as a function of microscopic properties and geometry at any stage of growth. In a second step, numerical tools for the computation of the effective properties were developed and validated. This validation is carried out using results available in the literature for some sub-classes of our model (namely, diffusion, diffusion/reaction and diffusion/advection problems in 2D systems). The behaviour of the macroscopic dispersion tensor for the complete model (diffusion/reaction/advection) in a three phase configuration is studied and the influence of different parameters such as the volume fractions of the phases, Peclet and Kinetic numbers is discussed. Thu, 01 Jan 2009 00:00:00 GMT http://hdl.handle.net/10985/9983 2009-01-01T00:00:00Z LETELLIER, Samuel AHMADI-SENICHAULT, Azita LASSEUX, Didier Transplantation of engineered tissues is of major interest as an alternative to autogenic alogenic or exogenic grafts. In this study, in vitro cartilage cell culture on a fibrous biodegradable polymer scaffold is under concern. The scaffold is first seeded with cells which adhere to the fibres and the system is then grown in a bioreactor. As reported in the literature, hydrodynamics and transport of nutrients and metabolic products during this growth process is of considerable importance, motivating our analysis. A one-equation macroscopic model was first developed in order to describe macroscopic mass transport during in vitro tissue growth using the volume averaging method. This model takes into account a three phase system composed of solid fibres, cell phase and fluid phase and allows determination of the macroscopic quantities as a function of microscopic properties and geometry at any stage of growth. In a second step, numerical tools for the computation of the effective properties were developed and validated. This validation is carried out using results available in the literature for some sub-classes of our model (namely, diffusion, diffusion/reaction and diffusion/advection problems in 2D systems). The behaviour of the macroscopic dispersion tensor for the complete model (diffusion/reaction/advection) in a three phase configuration is studied and the influence of different parameters such as the volume fractions of the phases, Peclet and Kinetic numbers is discussed.