Highly permeable media have the potential for triggering inertia effects in the case of saturated or unsaturated flows. They also lead to specific effects in the case of unsaturated flows due to the increased viscous interaction at the pore-scale, the potential effects of high capillary numbers and Bond numbers. Theoretical, experimental and numerical results will be given in this lecture concerning saturated flows with inertia effects. The, now classical, discussion about the various regimes observed when increasing the Reynolds number close to the Darcy regime will be reviewed. Indications will be given on the still open problem of the phenomenology at high Reynolds numbers, and theoretical aspects such as the upscaling RANS turbulence models and the development of macro-scale turbulent models. Brief indications will be given on the case of two-phase flows: new evidence about viscous interaction effects, the introduction of inertia terms in macro-scale models