  Concerned with Darcy's law with memory, originally developed by J.-L. Lions
\cite{Lions81}, this paper is devoted to studying non-stationary Stokes
equations on perforated domains. We obtain a sharp homogenization error in the
sense of energy norms, where the main challenge is to control the boundary
layers caused by the incompressibility condition. Our method is to construct
boundary-layer correctors associated with Bogovskii's operator, which is robust
enough to be applied to other problems of fluid mechanics on homogenization and
porous medium.
