On a relaxation model for non-equilibrium turbulent flows

In this work, we started with the development of an algebraic Reynolds stress model designed for a turbulent mixing layer. By comparison with the second-order models of L.R.R. and S.S.G., this model makes clear improvements as for the prediction of a mixing layer developing towards an asymptotic state. Thereafter, and in order to improve the performance of the algebraic model for turbulent flows that are far from equilibrium, we proposed a relaxation model similar to that proposed by Speziale and Xu. Using the relaxation model, we simulated numerically the time evolution of a rapid axisymmetric contraction. The obtained results bring a manifest confirmation of the validity of the model for non-equilibrium turbulent flows. (C) 2010 Academie des sciences. Publie par Elsevier Masson SAS. Tous droits reserves.