P.D.E's- partial differential equation Can anyone give me the name of this equation and what references i can find such equations :
$\left\{\begin{array}{ll}
-\mu \Delta u+(\lambda+\mu)\nabla(\mbox{div }u)=Au,\ \ \ \ \mu>0,\ \ \lambda>0\\
u=0 \ \ \ \ \partial \Omega 
\end{array}
\right.$

If it were $$\mu\Delta u + (\lambda + \mu) \nabla(\textrm{div} u)$$ (maybe your Laplacian has a different sign convention than mine?) it would be the "Static Lam\'e System" (see also "isotropic elasticity", "elastic wave equation" (a related, time-dependent PDE))
