LES of unsteady turbulence via a one-equation subgrid-scale transport model

The study of unsteady turbulent flows can lead to non-equilibrium turbulence spectra and there is a need to develop new subgrid-scale models that can be efficient in such situations. This is particularly necessary if the grid is coarse and the cutoff lies before the inertial zone of the spectrum. The model should be able to behave like a standard LES when the filter is sharp and like RANS models when the filter is wide, in a progressive way. The present work is a first step in that direction made by using transport equations for the subgrid-scale turbulence. We have used a transposition of the statistical model of Hassid and Poreh. The results of the simulations show that the one-equation model can predict the lag effects in the turbulent field response in pulsed channel flow, while the usual Smagorinsky model fails in several aspects.