https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Wed, 17 Jun 2026 01:29:08 GMT 2026-06-17T01:29:08Z http://hdl.handle.net/10985/6609 Transferts thermiques 3D dans des composites silice – phénolique: méthodes thermographiques et tomographiques AHMADI-SENICHAULT, Azita; VIGNOLES, Gérard; AYVAZYAN, Viguen; CATY, Olivier; BRESSON, Grégory; GREGORI, Maria Luisa; FONSECA COSTA, Sônia Nous présentons ici le développement d'une approche double pour la caractérisation thermique des matériaux composites. Sun, 01 Jan 2012 00:00:00 GMT http://hdl.handle.net/10985/6609 2012-01-01T00:00:00Z AHMADI-SENICHAULT, Azita VIGNOLES, Gérard AYVAZYAN, Viguen CATY, Olivier BRESSON, Grégory GREGORI, Maria Luisa FONSECA COSTA, Sônia Nous présentons ici le développement d'une approche double pour la caractérisation thermique des matériaux composites. http://hdl.handle.net/10985/8297 Essais d’impact et propriétés thermiques résiduelles sur composites silice/phénolique BRESSON, Grégory; CATY, Olivier; MERZEAU, Jonathan; DAU, Frédéric; AHMADI-SENICHAULT, Azita; VIGNOLES, Gérard Silica/phenolic composites are used in atmospheric re-entry heat shield parts in spatial and strategic domains. For this application, the material is submitted to thermo-mechanical stresses that lead to delaminations. To reduce the effect of these delaminations, it was proposed to cut silica fabrics and to reassemble them like a patchwork. « Classical » (2D 0°/90° fabric stacks) and « patchwork » materials were impacted on an instrumented falling-weight tower (Instron). These tests were carried out at different energies to create different levels of damage. The damaged samples were analysed by X-Ray micro computed tomography to reveal in particular the delaminations morphologies. In parallel, initial and residual transverse thermal diffusivity measurements were realised on these samples for different damage states. These measurements permitted setting up correlations between loss of thermal diffusivity and material damage. Comparisons between results on « classical » and « patchwork » samples have highlighted differences in damaging modes and a limited interest of the patchwork solution. Tue, 01 Jan 2013 00:00:00 GMT http://hdl.handle.net/10985/8297 2013-01-01T00:00:00Z BRESSON, Grégory CATY, Olivier MERZEAU, Jonathan DAU, Frédéric AHMADI-SENICHAULT, Azita VIGNOLES, Gérard Silica/phenolic composites are used in atmospheric re-entry heat shield parts in spatial and strategic domains. For this application, the material is submitted to thermo-mechanical stresses that lead to delaminations. To reduce the effect of these delaminations, it was proposed to cut silica fabrics and to reassemble them like a patchwork. « Classical » (2D 0°/90° fabric stacks) and « patchwork » materials were impacted on an instrumented falling-weight tower (Instron). These tests were carried out at different energies to create different levels of damage. The damaged samples were analysed by X-Ray micro computed tomography to reveal in particular the delaminations morphologies. In parallel, initial and residual transverse thermal diffusivity measurements were realised on these samples for different damage states. These measurements permitted setting up correlations between loss of thermal diffusivity and material damage. Comparisons between results on « classical » and « patchwork » samples have highlighted differences in damaging modes and a limited interest of the patchwork solution. http://hdl.handle.net/10985/9724 Two-phase non-Darcy flow in heterogeneous porous media: A numerical investigation AHMADI-SENICHAULT, Azita; ABBASIAN ARANI, Ali Akbar; LASSEUX, Didier Significant inertial effects are observed for many applications such as flow in the near-wellbore region, in very permeable reservoirs or in packed-bed reactors. In these cases, the classical description of two-phase flow in porous media by the generalized Darcy's law is no longer valid. Due to the lack of a formalized theoretical model confirmed experimentally, this study is based on a generalized Darcy-Forchheimer approach for modelling two-phase incompressible non-stationary inertial flow in porous media. In this model, the momentum conservation equation for each phase, , has a quadratic correction to generalized Darcy’s law and is expressed as: (=”w” for water or “o” for oil): (1) This equation is completed with the mass conservation equation for each phase given by (2) and the capillary pressure and saturation relationships (3) (4) Using a finite volume formulation, an IMPES (IMplicit for Pressures, Explicit for Saturations) scheme and a Fixed Point method for the treatment of non-linearities caused by inertia, a 3D numerical tool has been developed. For clarity, results are presented in 1D and 2D configurations only. For 1D flow in a homogeneous porous medium, a validation is performed by comparing numerical results of the saturation front kinetics with a semi-analytical solution inspired from the “Buckley-Leverett” model extended to take into account inertia. The influence of inertial effects on the saturation profiles and therefore on the breakthrough curves for homogeneous media is analysed for different Reynolds numbers, thus emphasizing the necessity of taking into account this additional energy loss when necessary. For 1D heterogeneous configurations, a thorough analysis of the saturation fronts as well as the saturation jumps at the interface between two media of contrasted properties highlights the influence of inertial effects for different Reynolds and capillary numbers. In 2D heterogeneous configurations, saturation distributions are strongly affected by inertial effects. In particular, capillary trapping of the displaced fluid observed for the Darcy regime in certain regions can completely disappears when inertial effects become dominant. Fri, 01 Jan 2010 00:00:00 GMT http://hdl.handle.net/10985/9724 2010-01-01T00:00:00Z AHMADI-SENICHAULT, Azita ABBASIAN ARANI, Ali Akbar LASSEUX, Didier Significant inertial effects are observed for many applications such as flow in the near-wellbore region, in very permeable reservoirs or in packed-bed reactors. In these cases, the classical description of two-phase flow in porous media by the generalized Darcy's law is no longer valid. Due to the lack of a formalized theoretical model confirmed experimentally, this study is based on a generalized Darcy-Forchheimer approach for modelling two-phase incompressible non-stationary inertial flow in porous media. In this model, the momentum conservation equation for each phase, , has a quadratic correction to generalized Darcy’s law and is expressed as: (=”w” for water or “o” for oil): (1) This equation is completed with the mass conservation equation for each phase given by (2) and the capillary pressure and saturation relationships (3) (4) Using a finite volume formulation, an IMPES (IMplicit for Pressures, Explicit for Saturations) scheme and a Fixed Point method for the treatment of non-linearities caused by inertia, a 3D numerical tool has been developed. For clarity, results are presented in 1D and 2D configurations only. For 1D flow in a homogeneous porous medium, a validation is performed by comparing numerical results of the saturation front kinetics with a semi-analytical solution inspired from the “Buckley-Leverett” model extended to take into account inertia. The influence of inertial effects on the saturation profiles and therefore on the breakthrough curves for homogeneous media is analysed for different Reynolds numbers, thus emphasizing the necessity of taking into account this additional energy loss when necessary. For 1D heterogeneous configurations, a thorough analysis of the saturation fronts as well as the saturation jumps at the interface between two media of contrasted properties highlights the influence of inertial effects for different Reynolds and capillary numbers. In 2D heterogeneous configurations, saturation distributions are strongly affected by inertial effects. In particular, capillary trapping of the displaced fluid observed for the Darcy regime in certain regions can completely disappears when inertial effects become dominant. http://hdl.handle.net/10985/9755 Towards a new method of porosimetry: principles and experiments RODRIGUEZ DE CASTRO, Antonio; AHMADI-SENICHAULT, Azita; BRUNEAU, Denis; OMARI, Aziz Current experimental methods used to determine pore size distributions (PSD) in porous media present several drawbacks such as toxicity of employed fluids (e.g. mercury porosimetry). Theoretical basis of a new method to obtain the PSD of porous media has been proposed in the literature [1, 2] ... Tue, 01 Jan 2013 00:00:00 GMT http://hdl.handle.net/10985/9755 2013-01-01T00:00:00Z RODRIGUEZ DE CASTRO, Antonio AHMADI-SENICHAULT, Azita BRUNEAU, Denis OMARI, Aziz Current experimental methods used to determine pore size distributions (PSD) in porous media present several drawbacks such as toxicity of employed fluids (e.g. mercury porosimetry). Theoretical basis of a new method to obtain the PSD of porous media has been proposed in the literature [1, 2] ... http://hdl.handle.net/10985/9928 Direct numerical simulation of colloid transport at the microscopic scale: influence of ionic strength in the presence of a rough surface SEFRIOUI, Nisrine; AHMADI-SENICHAULT, Azita; BERTIN, Henri; OMARI, Aziz The way colloids are transported, deposited or detached in porous media is of great importance in many practical problems such as filtration, environmental issues, petroleum engineering, … In this work, direct numerical simulations of the transport of a single particle near the fluid/solid interface have been performed. For this purpose, new routines have been implemented in a research code in order to take into account DLVO forces for smooth and rough pore surfaces. A dimensional analysis is performed, pointing out the important role of the ratio of electrostatic forces to the hydrodynamic forces on the particle behaviour. The test cases considered are chosen on the basis of experimental results presented in the literature. Transport of a particle near a solid surface is simulated for a given Reynolds number at different values of ionic strength and the influence of various surface roughness types are analysed. The simulations illustrate three different behaviours: (i) the particle is transported by the bulk fluid (ii) the particle is adsorbed and rolls on the solid surface (iii) the particle is adsorbed by the surface and is blocked. An analysis in terms of residence time is proposed. Simulations also show that an increase in the Reynolds number leads to the mobilisation of the particle in all cases studied. Sun, 01 Jan 2012 00:00:00 GMT http://hdl.handle.net/10985/9928 2012-01-01T00:00:00Z SEFRIOUI, Nisrine AHMADI-SENICHAULT, Azita BERTIN, Henri OMARI, Aziz The way colloids are transported, deposited or detached in porous media is of great importance in many practical problems such as filtration, environmental issues, petroleum engineering, … In this work, direct numerical simulations of the transport of a single particle near the fluid/solid interface have been performed. For this purpose, new routines have been implemented in a research code in order to take into account DLVO forces for smooth and rough pore surfaces. A dimensional analysis is performed, pointing out the important role of the ratio of electrostatic forces to the hydrodynamic forces on the particle behaviour. The test cases considered are chosen on the basis of experimental results presented in the literature. Transport of a particle near a solid surface is simulated for a given Reynolds number at different values of ionic strength and the influence of various surface roughness types are analysed. The simulations illustrate three different behaviours: (i) the particle is transported by the bulk fluid (ii) the particle is adsorbed and rolls on the solid surface (iii) the particle is adsorbed by the surface and is blocked. An analysis in terms of residence time is proposed. Simulations also show that an increase in the Reynolds number leads to the mobilisation of the particle in all cases studied. http://hdl.handle.net/10985/9749 Thermographic and tomographic methods for three-dimensional characterization of thermal diffusion in silica/phenolic composites AHMADI-SENICHAULT, Azita; VIGNOLES, Gérard; BRESSON, Grégory; CATY, Olivier; AYVAZYAN, Viguen; GREGORI, Maria Luisa; COSTA, S.F. Aeronautical and space vehicles include many parts made of composite materials. The thermal design of these materials is critical versus their application. Indeed, the presence of very high thermal gradients during use may cause many technological problems such as resistance to thermal shocks or ablation. Furthermore, certain manufacturing processes call upon very high thermal gradients. Hence, the knowledge and control of the evolution of thermal properties during manufacturing and use is essential. In this work the development of a dual approach for thermal characterization of composite materials is presented. The first method makes use of standard and specific experimental methods, while the second is based on upscaling tools. In the second, 2D microscopic and 3D tomographic images are used in a two-step upscaling process using the Volume Averaging Method with closure: microscopic scale to mesoscopic scale to macroscopic scale. The procedure starts from the knowledge of the properties of the elementary constituents (matrix and fibers) and their spatial arrangement. The method can also be applied to virtually generated images of composite materials and can therefore contribute to the creation of a “design tool” that can allow the prediction of the influence of the architecture of the fiber reinforcement on certain properties of the composites namely the heat conductivity tensor. The two approaches are applied to two silica/phenolic composites with different spatial organizations. These composites are often used in thermal protection systems for atmospheric re-entry. Numerical results are compared to experimental ones in terms of transverse and longitudinal thermal conductivities of the composites, and are found to be in good agreement. A discussion is made on the different possible sources of uncertainty for both methods. Wed, 01 Jan 2014 00:00:00 GMT http://hdl.handle.net/10985/9749 2014-01-01T00:00:00Z AHMADI-SENICHAULT, Azita VIGNOLES, Gérard BRESSON, Grégory CATY, Olivier AYVAZYAN, Viguen GREGORI, Maria Luisa COSTA, S.F. Aeronautical and space vehicles include many parts made of composite materials. The thermal design of these materials is critical versus their application. Indeed, the presence of very high thermal gradients during use may cause many technological problems such as resistance to thermal shocks or ablation. Furthermore, certain manufacturing processes call upon very high thermal gradients. Hence, the knowledge and control of the evolution of thermal properties during manufacturing and use is essential. In this work the development of a dual approach for thermal characterization of composite materials is presented. The first method makes use of standard and specific experimental methods, while the second is based on upscaling tools. In the second, 2D microscopic and 3D tomographic images are used in a two-step upscaling process using the Volume Averaging Method with closure: microscopic scale to mesoscopic scale to macroscopic scale. The procedure starts from the knowledge of the properties of the elementary constituents (matrix and fibers) and their spatial arrangement. The method can also be applied to virtually generated images of composite materials and can therefore contribute to the creation of a “design tool” that can allow the prediction of the influence of the architecture of the fiber reinforcement on certain properties of the composites namely the heat conductivity tensor. The two approaches are applied to two silica/phenolic composites with different spatial organizations. These composites are often used in thermal protection systems for atmospheric re-entry. Numerical results are compared to experimental ones in terms of transverse and longitudinal thermal conductivities of the composites, and are found to be in good agreement. A discussion is made on the different possible sources of uncertainty for both methods. 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/10985/10063 Etude expérimentale et numérique de la dissolution d’un polluant hydrocarboné dans un milieu poreux hétérogène YRA, Adrienne; AHMADI-SENICHAULT, Azita; BERTIN, Henri Le travail présenté traite de la dissolution d'un solvant partiellement miscible dans l'eau en milieu poreux hétérogène saturé. Une étude expérimentale réalisée à la fois sur des milieux poreux microscopiquement et macroscopiquement hétérogènes met en évidence des phénomènes de non équilibre local. Une interprétation numérique des données expérimentales est ensuite décrite. Mon, 01 Jan 2007 00:00:00 GMT http://hdl.handle.net/10985/10063 2007-01-01T00:00:00Z YRA, Adrienne AHMADI-SENICHAULT, Azita BERTIN, Henri Le travail présenté traite de la dissolution d'un solvant partiellement miscible dans l'eau en milieu poreux hétérogène saturé. Une étude expérimentale réalisée à la fois sur des milieux poreux microscopiquement et macroscopiquement hétérogènes met en évidence des phénomènes de non équilibre local. Une interprétation numérique des données expérimentales est ensuite décrite. http://hdl.handle.net/10985/9929 On the influence of ionic strength on colloid transport in porous media in the presence of a rough surface : numerical simulation at the microscopic scale SEFRIOUI, Nisrine; AHMADI-SENICHAULT, Azita; BERTIN, Henri; OMARI, Aziz The understanding of Colloids transport, deposit or detachment in porous media is of central importance in many practical problems such as filtration, environmental issues and petroleum engineering. In particular, the interaction of colloids with the grain surfaces is a complex problem involving combination of short range physico-chemical forces, acting at the “interface scale” with the hydrodynamics in the pore space. The understating of the processes at these small scales is crucial for the description of colloid transport processes under different physicochemical and hydrodynamic conditions at larger scales. General experimental features of colloid deposition and their detachment after a flooding with brine of ionic strength and pH different from the resident one have been reported in literature and successfully predicted using DLVO theory (Canseco et al., 2009). However and despite various efforts, such prediction remains only qualitative. It is usually believed that the observed discrepancies arise from grain or colloid heterogeneities. Such heterogeneities may concern electrostatic charge or surface topography or both.(Ducker et al., 1991; Elimelech & O’Melia, 1990). The objective of this work is to study the influence of grain surface roughness on the transport, deposit and detachment of a colloidal particle under various physicochemical and hydrodynamic conditions. For this purpose, direct numerical simulations of the transport of a single particle near the fluid/solid interface have been performed. Sun, 01 Jan 2012 00:00:00 GMT http://hdl.handle.net/10985/9929 2012-01-01T00:00:00Z SEFRIOUI, Nisrine AHMADI-SENICHAULT, Azita BERTIN, Henri OMARI, Aziz The understanding of Colloids transport, deposit or detachment in porous media is of central importance in many practical problems such as filtration, environmental issues and petroleum engineering. In particular, the interaction of colloids with the grain surfaces is a complex problem involving combination of short range physico-chemical forces, acting at the “interface scale” with the hydrodynamics in the pore space. The understating of the processes at these small scales is crucial for the description of colloid transport processes under different physicochemical and hydrodynamic conditions at larger scales. General experimental features of colloid deposition and their detachment after a flooding with brine of ionic strength and pH different from the resident one have been reported in literature and successfully predicted using DLVO theory (Canseco et al., 2009). However and despite various efforts, such prediction remains only qualitative. It is usually believed that the observed discrepancies arise from grain or colloid heterogeneities. Such heterogeneities may concern electrostatic charge or surface topography or both.(Ducker et al., 1991; Elimelech & O’Melia, 1990). The objective of this work is to study the influence of grain surface roughness on the transport, deposit and detachment of a colloidal particle under various physicochemical and hydrodynamic conditions. For this purpose, direct numerical simulations of the transport of a single particle near the fluid/solid interface have been performed. http://hdl.handle.net/10985/9722 Towards a new method of porosimetry: principles and experiments RODRIGUEZ DE CASTRO, Antonio; OMARI, Aziz; AHMADI-SENICHAULT, Azita; BRUNEAU, Denis Abstract Current experimental methods used to determine pore size distributions (PSD) of porous media present several drawbacks such as toxicity of the employed fluids (e.g., mercury porosimetry). The theoretical basis of a new method to obtain the PSD by injecting yield stress fluids through porous media and measuring the flow rate Q at several pressure gradients ∇P was proposed in the literature. On the basis of these theoretical considerations, an intuitive approach to obtain PSD from Q(∇P) is presented in this work. It relies on considering the extra increment of Q when ∇P is increased, as a consequence of the pores of smaller radius newly incorporated to the flow. This procedure is first tested and validated on numerically generated experiments. Then, it is applied to exploit data coming from laboratory experiments and the obtained PSD showgood agreement with the PSD deduced frommercury porosimetry. Tue, 01 Jan 2013 00:00:00 GMT http://hdl.handle.net/10985/9722 2013-01-01T00:00:00Z RODRIGUEZ DE CASTRO, Antonio OMARI, Aziz AHMADI-SENICHAULT, Azita BRUNEAU, Denis Abstract Current experimental methods used to determine pore size distributions (PSD) of porous media present several drawbacks such as toxicity of the employed fluids (e.g., mercury porosimetry). The theoretical basis of a new method to obtain the PSD by injecting yield stress fluids through porous media and measuring the flow rate Q at several pressure gradients ∇P was proposed in the literature. On the basis of these theoretical considerations, an intuitive approach to obtain PSD from Q(∇P) is presented in this work. It relies on considering the extra increment of Q when ∇P is increased, as a consequence of the pores of smaller radius newly incorporated to the flow. This procedure is first tested and validated on numerically generated experiments. Then, it is applied to exploit data coming from laboratory experiments and the obtained PSD showgood agreement with the PSD deduced frommercury porosimetry.