On certain Neumann problems for Quasilinear Parabolic Systems Modeling Multiphase Flows Hermano Frid∗ Juan Gonzalez Marin† Vladimir Shelukhin‡ We study the well-posedness of certain Neumann problems for N × N quasilinear parabolic systems uit + div (fi (u)v) = N X div (Bij (u)∇uj ), i = 1, . . . , N, j=1 which naturally appear as models in applications such as polydisperse suspensions and multiphase flows in porous media, among others. We obtain existence and uniqueness of smooth solutions assuming values on a physical invariant domain with no smallness assumption. The boundary value problems considered fi (u)v(x) − 2 X Bij (u)∇uj · ~n(x) = k0 u v(x) · ~n(x), i = 1, . . . , N, j=1 include the zero-flux Neumann problem for a model of polydisperse suspensions. The strategy is the use of the Leray-Schauder fixed point theorem, based on a priori estimates implying regularity in Hölder Spaces. As a first step towards the still open general multidimensional case, we consider the case of domains with radial symmetry. References [1] Berres, S., Bürger, R. and Frid, H. Neumann problems for quasi-linear parabolic systems modeling polydisperse suspensions. SIAM J. Math. Anal. 38 (2006), 557–573. [2] Chueh, K., Conley, C., Smoller, J., Positively invariant regions for systems of nonlinear diffusion equations, Ind. Univ. Math. J. 26 (1977), 373-392. [3] Frid, H. and Shelukhin, V., A quasi-linear parabolic system for three-phase capillary flow in porous media. SIAM J. Math. Anal. 35 (2003), no. 4, 1029–1041. ∗ Instituto de Matemática Pura e Aplicada - IMPA. Estrada Dona Castorina, 110. Rio de Janeiro, RJ 22460-320, Brazil, [email protected]. † Departamento de Matemática, Universidade Federal da Bahia, Av. Ademar de Barros s/n, Salvador, BA 40170-110 , Brazil, [email protected]. ‡ Lavrentyev Institute of Hydrodynamics, Novosibirsk, Russia, [email protected]. 1 [4] Frid, H. and Shelukhin, V., Initial boundary value problems for a quasilinear parabolic system in three-phase capillary flow in porous media, SIAM J. Math. Anal., 36 (2005), pp. 1407-1425. [5] Frid, H. Gonzalez, J. and Shelukhin, V., On certain Neumann problems for Quasilinear Parabolic Systems Modeling Multiphase Flows, to appear. [6] Ladyzhenskaya, O.A., Solonnikov, V.A., Ural’ceva, N.N., “Linear and Quasi-linear Equations of Parabolic Type”, Providence, R.I.: Amer. Math. Soc. 1968. 2
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