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The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Mon, 15 Apr 2024 15:02:02 GMT2024-04-15T15:02:02ZOne and two-fiber orientation kinetic theories of fiber suspensions
http://hdl.handle.net/10985/8488
One and two-fiber orientation kinetic theories of fiber suspensions
GRMELA, Miroslav; AMMAR, Amine; CHINESTA, Francisco
The morphology influencing rheological properties of suspensions of rigid spheres constitutes the flow induced collective ordering of the spheres characterized by two or more sphere distribution functions. When the rigid spheres are replaced by rigid fibers, the collective order in the position of the spheres is replaced by the flow induced orientation of the fibers that suffices to be characterized by one-fiber orientation distribution function. A flow induced collective ordering of fibers (both in position and orientation), that can only be characterized by two or more fiber distribution functions, can still however constitute an important part of the morphology. We show that two types of interaction among fibers, one being the Onsager-type topological interaction entering the free energy and the other the hydrodynamics interaction entering the dissipative part of the time evolution, give indeed rise to a collective order in the orientation influencing the rheology of fiber suspensions.
http://dx.doi.org/10.1016/j.jnnfm.2012.10.009
Tue, 01 Jan 2013 00:00:00 GMThttp://hdl.handle.net/10985/84882013-01-01T00:00:00ZGRMELA, MiroslavAMMAR, AmineCHINESTA, FranciscoThe morphology influencing rheological properties of suspensions of rigid spheres constitutes the flow induced collective ordering of the spheres characterized by two or more sphere distribution functions. When the rigid spheres are replaced by rigid fibers, the collective order in the position of the spheres is replaced by the flow induced orientation of the fibers that suffices to be characterized by one-fiber orientation distribution function. A flow induced collective ordering of fibers (both in position and orientation), that can only be characterized by two or more fiber distribution functions, can still however constitute an important part of the morphology. We show that two types of interaction among fibers, one being the Onsager-type topological interaction entering the free energy and the other the hydrodynamics interaction entering the dissipative part of the time evolution, give indeed rise to a collective order in the orientation influencing the rheology of fiber suspensions.A mesoscopic rheological model of moderately concentrated colloids
http://hdl.handle.net/10985/9962
A mesoscopic rheological model of moderately concentrated colloids
GRMELA, Miroslav; AMMAR, Amine; CHINESTA, Francisco; MAITREJEAN, Guillaume
We extend the Maffettone–Minale model by including non-elliptical shapes of dispersed particles, a new family of internal forces controlling particle deformations, and particle–particle interactions. The last extension is made by transposing the way the chain-chain interactions are mathematically expressed in the reptation theory to suspensions. The particle–particle interactions are regarded as a confinement to cages formed by surrounding particles and by introducing a new dissipative motion (an analog of the reptation motion) inside the cages. Nonlinear responses to imposed shear and elongational flows are found to be in qualitative agreement with available experimental data.
Wed, 01 Jan 2014 00:00:00 GMThttp://hdl.handle.net/10985/99622014-01-01T00:00:00ZGRMELA, MiroslavAMMAR, AmineCHINESTA, FranciscoMAITREJEAN, GuillaumeWe extend the Maffettone–Minale model by including non-elliptical shapes of dispersed particles, a new family of internal forces controlling particle deformations, and particle–particle interactions. The last extension is made by transposing the way the chain-chain interactions are mathematically expressed in the reptation theory to suspensions. The particle–particle interactions are regarded as a confinement to cages formed by surrounding particles and by introducing a new dissipative motion (an analog of the reptation motion) inside the cages. Nonlinear responses to imposed shear and elongational flows are found to be in qualitative agreement with available experimental data.Kinetic theory of colloidal suspensions: morphology, rheology, and migration
http://hdl.handle.net/10985/10262
Kinetic theory of colloidal suspensions: morphology, rheology, and migration
GRMELA, Miroslav; MAITREJEAN, Guillaume; CHINESTA, Francisco; AMMAR, Amine
Smoluchowski kinetic equation governing the time evolution of the pair correlation function of rigid sphericalparticles suspended in a Newtonian fluid is extended to include particle migration. The extended kinetic equation takes into account three types of forces acting on the suspended particles: a direct force generated by an interparticle potential, hydrodynamic force mediated by the host fluid, and the Faxén-type forces bringing about the across-the-streamline particle migration. For suspensions subjected to externally imposed flows, the kinetic equation is solved numerically by the proper generalized decomposition method. The imposed flow investigated inthe numerical illustrations is the Poiseuille flow. Numerical solutions provide the morphology (the pair correlation function), the rheology (the stress tensor), and the particle migration.
Tue, 01 Jan 2013 00:00:00 GMThttp://hdl.handle.net/10985/102622013-01-01T00:00:00ZGRMELA, MiroslavMAITREJEAN, GuillaumeCHINESTA, FranciscoAMMAR, AmineSmoluchowski kinetic equation governing the time evolution of the pair correlation function of rigid sphericalparticles suspended in a Newtonian fluid is extended to include particle migration. The extended kinetic equation takes into account three types of forces acting on the suspended particles: a direct force generated by an interparticle potential, hydrodynamic force mediated by the host fluid, and the Faxén-type forces bringing about the across-the-streamline particle migration. For suspensions subjected to externally imposed flows, the kinetic equation is solved numerically by the proper generalized decomposition method. The imposed flow investigated inthe numerical illustrations is the Poiseuille flow. Numerical solutions provide the morphology (the pair correlation function), the rheology (the stress tensor), and the particle migration.Deterministic solution of the kinetic theory model of colloidal suspensions of structureless particles
http://hdl.handle.net/10985/8466
Deterministic solution of the kinetic theory model of colloidal suspensions of structureless particles
MAITREJEAN, Guillaume; AMMAR, Amine; CHINESTA, Francisco; GRMELA, Miroslav
A direct modeling of colloidal suspensions consists of calculating trajectories of all suspended objects. Due to the large time computing and the large cost involved in such calculations, we consider in this paper another route. Colloidal suspensions are described on a mesoscopic level by a distribution function whose time evolution is governed by a Fokker–Plancklike equation. The difficulty encountered on this route is the high dimensionality of the space in which the distribution function is defined. A novel strategy is used to solve numerically the Fokker–Planck equation circumventing the curse of dimensionality issue. Rheological and morphological predictions of the model that includes both direct and hydrodynamic interactions are presented in different flows.
Sun, 01 Jan 2012 00:00:00 GMThttp://hdl.handle.net/10985/84662012-01-01T00:00:00ZMAITREJEAN, GuillaumeAMMAR, AmineCHINESTA, FranciscoGRMELA, MiroslavA direct modeling of colloidal suspensions consists of calculating trajectories of all suspended objects. Due to the large time computing and the large cost involved in such calculations, we consider in this paper another route. Colloidal suspensions are described on a mesoscopic level by a distribution function whose time evolution is governed by a Fokker–Plancklike equation. The difficulty encountered on this route is the high dimensionality of the space in which the distribution function is defined. A novel strategy is used to solve numerically the Fokker–Planck equation circumventing the curse of dimensionality issue. Rheological and morphological predictions of the model that includes both direct and hydrodynamic interactions are presented in different flows.