This thesis presents the study of the destabilization of a silicone oil under a porous horizontal plane continuously fed.We observe, varying the flow rate and the viscosity, a large spectum of spatiotemporal behaviors through three basic regimes built around drops, columns and curtains: centred hexagonal lattices, topolgical defects oscillating or not, spiral structures...Moreover, the threoretical study of the destabilization of a hexagonal stationnary pattern performed here, predicts all the possible wave vectors of the secondary instability, and in particular the period doubling mode observed in the experiment.The study of the transition towards spatiotemporal chaos via intermittency starting from a stationary hexagonal regime of columns has been performed. Depending on viscosity, the transition is of first or second order in the framework of thermodynamical systems.
