Large eddy simulations

Abstract

In practical applications high Reynolds numbers flow fields are requested, and the direct simulation cannot be achieved. In the early period of the numerical simulation of the Navier-Stokes equations turbulence models, based on Reynolds averages, were widely used. These one-point closures turbulence models, as was shown in the 1969 Stanford conference, gave reasonable results in boundary-layers with moderate pressure gradients. In the seventies the simulations were extended to complex flows with some success. The ad hoc constants in the models were evaluated by the help of measurements. The reason of the satisfactory results is linked to the physical assumptions introduced in the closure of the high order correlations. Thus, an interesting output of these turbulence models was that with a limited number of constants it was possible to obtain satisfactory results for different flows in a large range of Reynolds numbers. However, the users of these models, those working in the industries, were not satisfied and they were pushing the modellers to find more universal models.