A non-linear SGS model based on the spatial velocity increment - Application to LES of fully developed pipe flow and round turbulent jet

摘要

A new subgrid scale (SGS) modelling concept for large-eddy simulation (LES) of incompressible flow is proposed based on the three-dimensional spatial velocity increment delta u (i) . The new model is inspired by the structure function formulation developed by Metais and Lesieur [39] and applied in the context of the scale similarity type formulation. First, the similarity between the SGS stress tensor tau(ij) and the velocity increment tensor Q(ij) = delta u(i)delta u(j) is analyzed analytically and numerically using a priori tests of fully developed pipe flow at Re-tau = 180. Both forward and backward energy transfers between resolved and unresolved scales of the flow are well predicted with a SGS model based on Q(ij) . Secondly, a posteriori tests are performed for two families of turbulent shear flows. LES of fully developed pipe flow up to Re-tau = 520 and LES of round turbulent jet at Re-D = 25000 carried out with a dynamic version of the model provide promising results that confirm the power of this approach for wall-bounded and free shear flows.