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Browsing by Author "Oliveira, H. B. de"

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  • Cauchy problem for the Navier–Stokes–Voigt model governing nonhomogeneous flows
    Publication . Antontsev, S. N.; Oliveira, H. B. de
    The Navier-Stokes-Voigt model that governs flows with non-constant density of incompressible fluids with elastic properties is considered in the whole space domain R-d and in the entire time interval. If d is an element of{2,3,4}, we prove the existence of weak solutions (velocity, density and pressure) to the associated Cauchy problem. We also analyse some issues of regularity of the weak solutions to the considered problem and the large time behavior in special unbounded domains.
    2022Journal article Restricted Show more
  • Kelvin-Voigt equations with anisotropic diffusion, relaxation and damping: Blow-up and large time behavior
    Publication . Antontsev, S.; Oliveira, H. B. de; Khompysh, Kh
    A nonlinear initial and boundary-value problem for the Kelvin-Voigt equations with anisotropic diffusion, relaxation and absorption/damping terms is considered in this work. The global and local unique solvability of the problem was established in (J. Math. Anal. Appl. 473(2) (2019) 1122-1154). In the present work, we show how all the anisotropic exponents of nonlinearity and all anisotropic coefficients should interact with the problem data for the solutions of this problem display exponential and polynomial time-decays. We also establish the conditions for the solutions of this problem to blow-up in a finite time in three different cases: problem without convection, full anisotropic problem, and the problem with isotropic relaxation.
    2021Journal article Restricted Show more
  • The classical Kelvin-Voigt problem for incompressible fluids with unknown non-constant density: existence, uniqueness and regularity
    Publication . Antontsev, S. N.; Oliveira, H. B. de; Khompysh, Kh
    The classical Kelvin-Voigt equations for incompressible fluids with non-constant density are investigated in this work. To the associated initial-value problem endowed with zero Dirichlet conditions on the assumed Lipschitz-continuous boundary, we prove the existence of weak solutions: velocity and density. We also prove the existence of a unique pressure. These results are valid for d is an element of {2, 3, 4}. In particular, if d is an element of {2, 3}, the regularity of the velocity and density is improved so that their uniqueness can be shown. In particular, the dependence of the regularity of the solutions on the smoothness of the given data of the problem is established.
    2021-05Journal article Restricted Show more