Well-posedness for a class of non-Newtonian fluids with general growth conditions (original) (raw)

2009, Nonlocal and Abstract Parabolic Equations and their Applications

The paper concerns uniqueness of weak solutions to non-Newtonian fluids with nonstandard growth conditions for the Cauchy stress tensor. We recall the results on existence of weak solutions and additionally provide the proof of existence of measure-valued solutions. Motivated by the fluids of strongly inhomogeneous behaviour and having the property of rapid shear thickening we observe that the described situation cannot be captured by power-lawtype rheology. We describe the growth conditions with the help of general x-dependent convex functions. This formulation yields the existence of solutions in generalized Orlicz spaces. These considerations are motivated by e.g. electrorheological fluids, magnetorheological fluids, and shear thickening fluids.

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Monotonicity methods in generalized Orlicz spaces for a class of non-Newtonian fluids

Mathematical Methods in the Applied Sciences, 2009

Communicated by M. Lachowicz The paper concerns existence of weak solutions to the equations describing a motion of some non-Newtonian fluids with non-standard growth conditions of the Cauchy stress tensor. Motivated by the fluids of strongly inhomogeneous behavior and having the property of rapid shear thickening, we observe that the L p framework is not suitable to capture the described situation. We describe the growth conditions with the help of general x-dependent convex function. This formulation yields the existence of solutions in generalized Orlicz spaces. As examples of motivation for considering non-Newtonian fluids in such spaces, we recall the electrorheological fluids, magnetorheological fluids, and shear thickening fluids. The existence of solutions is established by the generalization of the classical Minty method to non-reflexive spaces. The result holds under the assumption that the lowest growth of the Cauchy stress is greater than the critical exponent q = (3d+2) / (d+2), where d is for space dimension. The restriction on the exponent q is forced by the convective term.

Existence of Strong Solutions for Incompressible Fluids with Shear Dependent Viscosities

2010

Certain rheological behavior of non-Newtonian fluids in engineering sciences is often modeled by a power law ansatz with p ∈ (1, 2]. In the present paper the local in time existence of strong solutions is studied. The main result includes also the degenerate case (δ = 0) of the extra stress tensor and thus improves previous results of [L. Diening and M. Růžička,

Unsteady flows of heat-conducting non-Newtonian fluids in Musielak–Orlicz spaces

Nonlinearity, 2018

Our purpose is to show the existence of weak solutions for unsteady flow of non-Newtonian incompressible nonhomogeneous, heat-conducting fluids with generalised form of the stress tensor without any restriction on its upper growth. Motivated by fluids of nonstandard rheology we focus on the general form of growth conditions for the stress tensor which makes anisotropic Musielak-Orlicz spaces a suitable function space for the considered problem. We do not assume any smallness condition on initial data in order to obtain long-time existence. Within the proof we use monotonicity methods, integration by parts adapted to nonreflexive spaces and Young measure techniques.

On a variational inequality for incompressible non-Newtonian thick flows

Contemporary Mathematics, 2016

In this work we extend the results on the existence, uniqueness and continuous dependence of strong solutions to a class of variational inequalities for incompressible non-Newtonian flows under the constraint of a variable maximum admissible shear rate. These fluids correspond to a limit case of shear-thickening viscosity, also called thick fluids, in which the solutions belong to a time dependent convex set with bounded deformation rate tensors. We also prove the existence of stationary solutions, which are the unique asymptotic limit of evolutionary flows in the case of sufficiently large viscosity. Dedicated to Hugo Beirão da Veiga on the occasion of his 70 th birthday

On steady flow of non-Newtonian fluids with frictional boundary conditions in reflexive Orlicz spaces

Nonlinear Analysis-real World Applications, 2018

A stationary viscous incompressible non-Newtonian fluid flow problem is studied with a non-polynomial growth of the extra (viscous) part of the Cauchy stress tensor together with a multivalued nonmonotone frictional boundary condition described by the Clarke subdifferential. We provide an abstract result on existence of solution to a subdifferential operator inclusion and a hemivariational inequality in the reflexive Orlicz-Sobolev space setting modeling the flow phenomenon. We establish the existence result, and under additional conditions, also uniqueness of a weak solution in the Orlicz-Sobolev space to the flow problem.

On the behavior in time of solutions to motion of Non-Newtonian fluids

Nonlinear Differential Equations and Applications NoDEA, 2020

We study the behavior on time of weak solutions to the non-stationary motion of an incompressible fluid with shear rate dependent viscosity in bounded domains when the initial velocity {u}_0 {\in } {L}^2u0∈L2.Ourestimatesshowthedifferentbehaviorofthesolutionasthegrowthconditionofthestresstensorvaries.Inthe“dilatant”or“shearthickening”caseweprovethatthedecayratedoesnotdependonu 0 ∈ L 2 . Our estimates show the different behavior of the solution as the growth condition of the stress tensor varies. In the “dilatant” or “shear thickening” case we prove that the decay rate does not depend onu0L2.Ourestimatesshowthedifferentbehaviorofthesolutionasthegrowthconditionofthestresstensorvaries.Inthedilatantorshearthickeningcaseweprovethatthedecayratedoesnotdependonu_0$$ u 0 , then our estimates also apply for irregular initial velocity.

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