The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
Josef žabenský - One of the best experts on this subject based on the ideXlab platform.
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on a navier stokes fourier like system capturing transitions between viscous and inviscid fluid regimes and between no slip and perfect slip boundary conditions
Nonlinear Analysis-real World Applications, 2018Co-Authors: Erika Maringova, Josef žabenskýAbstract:We study a generalization of the Navier–Stokes–Fourier system for an incompressible fluid where the deviatoric part of the Cauchy Stress Tensor is related to the symmetric part of the velocity gradient via a maximal monotone 2-graph that is continuously parametrized by the temperature. As such, the considered fluid may go through transitions between three of the following regimes: it can flow as a Bingham fluid for a specific value of the temperature, while it can behave as the Navier–Stokes fluid for another value of the temperature or, for yet another temperature, it can respond as the Euler fluid until a certain activation initiates the response of the Navier–Stokes fluid. At the same time, we regard a generalized threshold slip on the boundary that also may go through various regimes continuously with the temperature. All material coefficients like the kinematic viscosity, friction or activation coefficients are assumed to be temperature-dependent. We establish the large-data and long-time existence of weak solutions, applying the L ∞ L ∞ -truncation technique to approximate the velocity field.
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on a navier stokes fourier like system capturing transitions between viscous and inviscid fluid regimes and between no slip and perfect slip boundary conditions
arXiv: Analysis of PDEs, 2017Co-Authors: Erika Maringova, Josef žabenskýAbstract:We study a generalization of the Navier-Stokes-Fourier system for an incompressible fluid where the deviatoric part of the Cauchy Stress Tensor is related to the symmetric part of the velocity gradient via a maximal monotone 2-graph that is continuously parametrized by the temperature. As such, the considered fluid may go through transitions between three of the following regimes: it can flow as a Bingham fluid for a specific value of the temperature, while it can behave as the Navier-Stokes fluid for another value of the temperature or, for yet another temperature, it can respond as the Euler fluid until a certain activation initiates the response of the Navier-Stokes fluid. At the same time, we regard a generalized threshold slip on the boundary that also may go through various regimes continuously with the temperature. All material coefficients like the dynamic viscosity, friction or activation coefficients are assumed to be temperature-dependent. We establish the large-data and long-time existence of weak solutions, applying the $L^{\infty}$-truncation technique to approximate the velocity field.
Ronaldo I Orja - One of the best experts on this subject based on the ideXlab platform.
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on the mechanical energy and effective Stress in saturated and unsaturated porous continua
International Journal of Solids and Structures, 2006Co-Authors: Ronaldo I OrjaAbstract:Abstract This paper has two objectives: (a) to formulate a mechanical theory of porous continua within the framework of strong discontinuity concept commonly employed for the analysis of strain localization in inelastic solids; and (b) to introduce an effective Stress Tensor for three-phase (solid–water–air) partially saturated porous continua emerging from principles of thermodynamics. To achieve the first objective, strong forms of the boundary-value problems are compared between two formulations, the first in which the velocity jump at the solid–fluid interface is treated as a strong discontinuity problem, and the second in which the strong discontinuity is smeared in the representative volume element. As for the second objective, an effective Cauchy Stress Tensor of the form σ ¯ = σ + ( 1 - K / K s ) p ¯ 1 emerges from the formulation, where σ is the total Stress Tensor, K and Ks are the bulk moduli of the solid matrix and solid phase, respectively, and p ¯ is the mean pore water and pore air pressures weighted according to the degree of saturation. We show from the first and second laws of thermodynamics that this effective Stress Tensor is power-conjugate to the solid rate of deformation Tensor, and that it includes the mechanical power required to compress the solid phase.
Azad Koliji - One of the best experts on this subject based on the ideXlab platform.
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on the effective Stress in unsaturated porous continua with double porosity
Journal of The Mechanics and Physics of Solids, 2009Co-Authors: Ronaldo I Borja, Azad KolijiAbstract:Abstract Using mixture theory we formulate the balance laws for unsaturated porous media composed of a double-porosity solid matrix infiltrated by liquid and gas. In this context, the term ‘double porosity’ pertains to the microstructural characteristic that allows the pore spaces in a continuum to be classified into two pore subspaces. We use the first law of thermodynamics to identify energy-conjugate variables and derive an expression for the ‘effective’, or constitutive, Stress that is energy-conjugate to the rate of deformation of the solid matrix. The effective Stress has the form σ ¯ = σ + B p ¯ 1 , where σ is the total Cauchy Stress Tensor, B is the Biot coefficient, and p ¯ is the mean fluid pressure weighted according to the local degrees of saturation and pore fractions. We identify other emerging energy-conjugate pairs relevant for constitutive modeling of double-porosity unsaturated continua, including the local suction versus degree of saturation pair and the pore volume fraction versus weighted pore pressure difference pair. Finally, we use the second law of thermodynamics to determine conditions for maximum plastic dissipation in the regime of inelastic deformation for the unsaturated two-porosity mixture.
Erika Maringova - One of the best experts on this subject based on the ideXlab platform.
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on a navier stokes fourier like system capturing transitions between viscous and inviscid fluid regimes and between no slip and perfect slip boundary conditions
Nonlinear Analysis-real World Applications, 2018Co-Authors: Erika Maringova, Josef žabenskýAbstract:We study a generalization of the Navier–Stokes–Fourier system for an incompressible fluid where the deviatoric part of the Cauchy Stress Tensor is related to the symmetric part of the velocity gradient via a maximal monotone 2-graph that is continuously parametrized by the temperature. As such, the considered fluid may go through transitions between three of the following regimes: it can flow as a Bingham fluid for a specific value of the temperature, while it can behave as the Navier–Stokes fluid for another value of the temperature or, for yet another temperature, it can respond as the Euler fluid until a certain activation initiates the response of the Navier–Stokes fluid. At the same time, we regard a generalized threshold slip on the boundary that also may go through various regimes continuously with the temperature. All material coefficients like the kinematic viscosity, friction or activation coefficients are assumed to be temperature-dependent. We establish the large-data and long-time existence of weak solutions, applying the L ∞ L ∞ -truncation technique to approximate the velocity field.
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on a navier stokes fourier like system capturing transitions between viscous and inviscid fluid regimes and between no slip and perfect slip boundary conditions
arXiv: Analysis of PDEs, 2017Co-Authors: Erika Maringova, Josef žabenskýAbstract:We study a generalization of the Navier-Stokes-Fourier system for an incompressible fluid where the deviatoric part of the Cauchy Stress Tensor is related to the symmetric part of the velocity gradient via a maximal monotone 2-graph that is continuously parametrized by the temperature. As such, the considered fluid may go through transitions between three of the following regimes: it can flow as a Bingham fluid for a specific value of the temperature, while it can behave as the Navier-Stokes fluid for another value of the temperature or, for yet another temperature, it can respond as the Euler fluid until a certain activation initiates the response of the Navier-Stokes fluid. At the same time, we regard a generalized threshold slip on the boundary that also may go through various regimes continuously with the temperature. All material coefficients like the dynamic viscosity, friction or activation coefficients are assumed to be temperature-dependent. We establish the large-data and long-time existence of weak solutions, applying the $L^{\infty}$-truncation technique to approximate the velocity field.
Ronaldo I Borja - One of the best experts on this subject based on the ideXlab platform.
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on the effective Stress in unsaturated porous continua with double porosity
Journal of The Mechanics and Physics of Solids, 2009Co-Authors: Ronaldo I Borja, Azad KolijiAbstract:Abstract Using mixture theory we formulate the balance laws for unsaturated porous media composed of a double-porosity solid matrix infiltrated by liquid and gas. In this context, the term ‘double porosity’ pertains to the microstructural characteristic that allows the pore spaces in a continuum to be classified into two pore subspaces. We use the first law of thermodynamics to identify energy-conjugate variables and derive an expression for the ‘effective’, or constitutive, Stress that is energy-conjugate to the rate of deformation of the solid matrix. The effective Stress has the form σ ¯ = σ + B p ¯ 1 , where σ is the total Cauchy Stress Tensor, B is the Biot coefficient, and p ¯ is the mean fluid pressure weighted according to the local degrees of saturation and pore fractions. We identify other emerging energy-conjugate pairs relevant for constitutive modeling of double-porosity unsaturated continua, including the local suction versus degree of saturation pair and the pore volume fraction versus weighted pore pressure difference pair. Finally, we use the second law of thermodynamics to determine conditions for maximum plastic dissipation in the regime of inelastic deformation for the unsaturated two-porosity mixture.