A-Posteriori Test of LES Closure Models for Free- Surface Flows

Naval hydrodynamics is characterized not only by a very high Reynolds number regime but also by peculiar geometry conditions as free surface and juncture flows. The most relevant aspects of these type of turbulent flows occur in the decaying conditions when the external cause that forces turbulence is removed. In essence, during the decaying period the flow field suffers a transition from three-dimensional to two-dimensional structure at the free surface. Preliminary numerical simulations of a free-surface turbulent channel flow have been performed by means of code based on a difference scheme second order accurate both in time and space and the Smagorinsky approach as closure model. The numerical results show a general agreement with the experiment and direct numerical simulations, but the quality of approximation is poor.