2,998 research outputs found
Global existence and blow-up of solutions to porous medium equation and pseudo-parabolic equation, I. Stratified Groups
In this paper, we prove a global existence and blow-up of the positive solutions to the initial-boundary value problem of the nonlinear porous medium equation and the nonlinear pseudo-parabolic equation on the stratified Lie groups. Our proof is based on the concavity argument and the Poincar\'e inequality, established in [38] for stratified groups
On the lifespan of classical solutions to a non-local porous medium problem with nonlinear boundary conditions
In this paper we analyze the porous medium equation
\begin{equation}\label{ProblemAbstract} \tag{} %\begin{cases}
u_t=\Delta u^m + a\io u^p-b u^q -c\lvert\nabla\sqrt{u}\rvert^2 \quad
\textrm{in}\quad \Omega \times I,%\\ %u_\nu-g(u)=0 & \textrm{on}\; \partial
\Omega, t>0,\\ %u({\bf x},0)=u_0({\bf x})&{\bf x} \in \Omega,\\ %\end{cases}
\end{equation} where is a bounded and smooth domain of , with
, and is the maximal interval of existence for . The
constants are positive, proper real numbers larger than 1 and
the equation is complemented with nonlinear boundary conditions involving the
outward normal derivative of . Under some hypothesis on the data, including
intrinsic relations between and , and assuming that for some positive
and sufficiently regular function u_0(\nx) the Initial Boundary Value Problem
(IBVP) associated to \eqref{ProblemAbstract} possesses a positive classical
solution u=u(\nx,t) on : \begin{itemize} \item
[] when and in 2- and 3-dimensional domains, we determine
a \textit{lower bound of} for those becoming unbounded in
at such ; \item [] when and in
-dimensional settings, we establish a \textit{global existence criterion}
for . \end{itemize
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