3,112 research outputs found

    Existence of global weak solutions to compressible isentropic finitely extensible bead-spring chain models for dilute polymers

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    We prove the existence of global-in-time weak solutions to a general class of models that arise from the kinetic theory of dilute solutions of nonhomogeneous polymeric liquids, where the polymer molecules are idealized as bead-spring chains with finitely extensible nonlinear elastic (FENE) type spring potentials. The class of models under consideration involves the unsteady, compressible, isentropic, isothermal Navier–Stokes system in a bounded domain Ω in Rd, d = 2 or 3, for the density ρ, the velocity u∼ and the pressure p of the fluid, with an equation of state of the form p(ρ) = cpρ γ, where cp is a positive constant and γ > 3 2 . The right-hand side of the Navier–Stokes momentum equation includes an elastic extra-stress tensor, which is the sum of the classical Kramers expression and a quadratic interaction term. The elastic extra-stress tensor stems from the random movement of the polymer chains and is defined through the associated probability density function that satisfies a Fokker–Planck-type parabolic equation, a crucial feature of which is the presence of a centre-of-mass diffusion term

    Finite element approximation of a degenerate Allen-Cahn/Cahn-Hilliard system

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    Lakes and rivers in the landscape: A quasi-variational inequality approach

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