This thesis, which is in the context of the ANR DIB project, aims at : a hybrid method (DDES) of the turbulent ow modeling around a thick plate (Re = 80000), a detailed comparison about the unsteady motion between this simulation and the experimental database, and a studying of the mechanisms of the pressure uctuation generation on the wall. The ow has successively a strong detachment associated with the vortex shedding which interacts intensively with the wall, a mean reattachment and then a slow recovery to a developed boundary layer. We are interested in the downstream region of the reattachment. The mean and unsteady characteristics are studied not only by the classical tools of statistics but also by the conditional average, the POD, the LSE and the Extended POD in their multi-time approach. A good agreement between the modeling and the experiment is obtained, and the simulation reproduces well the evolution of the large-scale vortex structures at the downstream of the mean reattachment. This analysis is extended to explore the ow three-dimensionality, and then we study the di erent contributions to the uctuating wall pressure (linear and nonlinear source terms). The analysis by the LSE based on the wall pressure shows the quasi 2D vortex rolls of low energy, whereas the hairpin vortices are observed by the one based on the velocity. A great result about the contribution to the wall pressure is that an important contribution comes from the nonlinear term, which explains the low energy carried by the structures estimated from the wall pressure by the linear tools.
