This chapter reviews the literature on numerical simulation of porous materials with a special focus on coastal structures. Flow through porous media has been studied in multiple science and engineering branches. A boom in numerical modelling started from 2010, boosted by more accessible and efficient computations. The development of these models was accompanied by a thorough study of the volume-averaged equations. Energy is dissipated via viscous effects and wakes. The size, shape and arrangement of the solids inside the medium also play an important role. A single porosity only suffices to represent a system with a unique fluid phase and an obstacle. The starting point of the derivation are the classical Reynolds-Averaged Navier-Stokes equations, the mass conservation and the momentum conservation equations. Further research also needs to be pursued to shed light in the flow kinematics and dynamics through interfaces.