Existence of positive solutions to a nonlinear elliptic system with nonlinearity involving gradient term

Abstract

In this work we analyze the existence of solutions to the nonlinear elliptic system: \begin{equation*} \left\{ \begin{array}{rcll} -Δu & = & v^q+\a g & \text{in }Ω, \\ -Δv& = &|\nabla u|^{p}+łf &\text{in }Ω, \\ u=v&=& 0 & \text{on }\partial Ω,\\ u,v& \geq & 0 & \text{in }Ω, \end{array}% \right. \end{equation*} where $Ω$ is a bounded domain of $\ren$ and $p\ge 1$, $q>0$ with $pq>1$. $f,g$ are nonnegative measurable functions with additional hypotheses and $\a, ł\ge 0$. As a consequence we show that the fourth order problem \begin{equation*} \left\{ \begin{array}{rcll} Δ^2 u & = &|\nabla u|^{p}+\tildeł \tilde{f} &\text{in }Ω, \\ u=\D u&=& 0 & \text{on }\partial Ω,\\ \end{array}% \right. \end{equation*} has a solution for all $p>1$, under suitable conditions on $\tilde{f}$ and $\tildeł$.