Abstract:Today, even though the Clausius-Duhem inequality is widely considered to be of central importance in the subject of continuum thermomechanics, it is also believed to be a somewhat special interpretation of a more fundamental (second) law of thermodynamics. In this work, which is concerned with the relation between thermodynamics and stability for a class of non-Newtonian incompressible fluids of the differential type, we find it essential to introduce the additional thermodynamical restriction that the Helmhol… Show more
“…Finally, since our models for the stress tensor and the heat flux vector are nonlinear, it is important to do stability analyses and consider the uniqueness and existence of solutions. This is left for future studies (see [61][62][63]). …”
Flowing media in both industrial and natural processes are often characterized as assemblages of densely packed granular materials. Typically, the constitutive relations for the stress tensor and heat flux vector are fundamentally nonlinear. Moreover, these equations are coupled through the Clausius-Duhem inequality. However, the consequences of this coupling are rarely studied. Here we address this issue by obtaining constraints imposed by the Clausius-Duhem inequality on the constitutive relations for both the stress tensor and the heat flux vector in which the volume fraction gradient plays an important role. A crucial result of the analysis is the restriction on the dependency of phenomenological coefficients appearing in the constitutive equations on the model objective functions.
“…Finally, since our models for the stress tensor and the heat flux vector are nonlinear, it is important to do stability analyses and consider the uniqueness and existence of solutions. This is left for future studies (see [61][62][63]). …”
Flowing media in both industrial and natural processes are often characterized as assemblages of densely packed granular materials. Typically, the constitutive relations for the stress tensor and heat flux vector are fundamentally nonlinear. Moreover, these equations are coupled through the Clausius-Duhem inequality. However, the consequences of this coupling are rarely studied. Here we address this issue by obtaining constraints imposed by the Clausius-Duhem inequality on the constitutive relations for both the stress tensor and the heat flux vector in which the volume fraction gradient plays an important role. A crucial result of the analysis is the restriction on the dependency of phenomenological coefficients appearing in the constitutive equations on the model objective functions.
“…More precisely (cf. [9]) the following result holds: if the Clausius-Duhem inequality is satisfied and the free energy is minimum at equilibrium then ν ≥ 0, β 1 = β 2 = 0, β≥ 0, α 1 ≥ 0.…”
Section: Introductionmentioning
confidence: 99%
“…We consider the matrices 3 × 3 as elements of L p (Ω) 9 and we define their norms L p by using (2.6) with N = 9. In the same way, we define the norms of tensors.…”
Section: Statement Of the Problem And Notationmentioning
Abstract. This paper shows that the decomposition method with special basis, introduced by Cioranescu and Ouazar, allows one to prove global existence in time of the weak solution for the third grade fluids, in three dimensions, with small data. Contrary to the special case where |α1 + α2| ≤ (24νβ) 1/2 , studied by Amrouche and Cioranescu, the H 1 norm of the velocity is not bounded for all data. This fact, which led others to think, in contradiction to this paper, that the method of decomposition could not apply to the general case of third grade, complicates substantially the proof of the existence of the solution. We also prove further regularity results by a method similar to that of Cioranescu and Girault for second grade fluids. This extension to the third grade fluids is not straightforward, because of a transport equation which is much more complex.Résumé. Dans cet article, on montre que la méthode de décomposition avec base spéciale introduite par Cioranescu et Ouazar, permet de démontrer l'existence globale en temps de la solution faible pour les fluides de grade trois, en dimension trois, avec des données petites. Contrairement au cas particulier où |α1 + α2| ≤ (24νβ) 1/2 ,étudié par Amrouche et Cioranescu, la norme H 1 de la vitesse n'est pas majorée pour toute donnée. Ce fait, qui conduisaità penser, en contradiction avec cet article, que la méthode de décomposition ne pouvait pas s'appliquer au cas général du grade trois, complique substantiellement la démonstration d'existence de la solution. Onétablit des résultats de régularité par une méthode similaireà celle de Cioranescu et Girault pour des fluides
“…Above, u(x) denotes the velocity vector field, p is the fluid pressure, L denotes the gradient matrix of the velocity L = ∇u = (∂ j u i ) i,j , A = L + L t and ν, α 1 , α 2 , β are some material constants that, according to the thermodynamic study performed by Fosdick and Rajagopal [14], must verify the following assumptions:…”
Abstract. Let Ω be a simply connected, bounded, smooth domain of R 2 or R 3 . We consider the equation of steady motion of a third grade fluid in Ω with homogeneous Dirichlet boundary conditions. We prove that the monotonicity technique used by Paicu [17] in the full space for unsteady motion allows to obtain the existence of a W 1,4 0 solution provided that the forcing belongs to W −1, 4 3 . The size of the forcing is arbitrary.
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