55 research outputs found
Sharp estimates for the global attractor of scalar reaction-diffusion equations with a Wentzell boundary condition
In this paper, we derive optimal upper and lower bounds on the dimension of
the attractor AW for scalar reaction-diffusion equations with a Wentzell
(dynamic) boundary condition. We are also interested in obtaining explicit
bounds about the constants involved in our asymptotic estimates, and to compare
these bounds to previously known estimates for the dimension of the global
attractor AK; K \in {D;N; P}, of reactiondiffusion equations subject to
Dirichlet, Neumann and periodic boundary conditions. The explicit estimates we
obtain show that the dimension of the global attractor AW is of different order
than the dimension of AK; for each K \in {D;N; P} ; in all space dimensions
that are greater or equal than three.Comment: to appear in J. Nonlinear Scienc
Hyperbolic Relaxation of Reaction Diffusion Equations with Dynamic Boundary Conditions
Under consideration is the hyperbolic relaxation of a semilinear
reaction-diffusion equation on a bounded domain, subject to a dynamic boundary
condition. We also consider the limit parabolic problem with the same dynamic
boundary condition. Each problem is well-posed in a suitable phase space where
the global weak solutions generate a Lipschitz continuous semiflow which admits
a bounded absorbing set. We prove the existence of a family of global
attractors of optimal regularity. After fitting both problems into a common
framework, a proof of the upper-semicontinuity of the family of global
attractors is given as the relaxation parameter goes to zero. Finally, we also
establish the existence of exponential attractors.Comment: to appear in Quarterly of Applied Mathematic
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