Accepted for Publication. This research was supported by a fundamental project grant from ANR (French National Research Agency - ANR Blancs): Séchelles (PI S. Descombes - 2009-2013) and by a DIGITEO RTRA project: MUSE (PI M. Massot - 2010-2014). The support of the France-Stanford Center for Interdisciplinary Studies through a collaborative project grant entitled "Multi-scale mathematical modeling and numerical methods for multiphase and reactive flows" (PIs: P. Moin and M. Massot) has been very helpful. We also acknowledge the computational resources of the Mesocentre of Ecole Centrale Paris where some of the simulations were performed.
