A novel dynamic coherent eddy model and its application to LES of a turbulent jet with free surface

Abstract

We has developed a novel dynamic coherent eddy model, in which the coherent structure—Q criterion introduced by Hunt et al (1988)—is taken into account in the subgrid-scale turbulent viscosity based on the eddy viscosity model. One proposed method is to combine the resolved-scale velocity-gradient tensor in the classical Smagorinsky model with Q criterion weighted. A kind of dynamic procedure which was averaged in a general process at temporal direction based on the autocorrelations of the characteristic resolved scales of turbulence was taken for the coefficient of subgrid model. The model is implemented in the σ-coordinate and the filtered Navier-Stokes equations are solved by the operator splitting method. The validation was explored to 2-D turbulent slot jet both in ambient environment and in regular waves. The prediction of the present model was compared with the experiment data, including the averaged velocity profiles, the velocity fluctuations and the Reynolds stress. The model performance is shown to be satisfactory.