Numerical simulations of density jumps

Colloque avec actes et comité de lecture. Internationale.International audienceThe density jump in a two-layer flow of miscible fluids is treated, focusing on the case that one of the layers is infinitely deep and at rest, based on the momentum and mass flux conservation equations. The influence of the uneven velocity and density profiles is considered and the new generalized equations are verified by a series of numerical simulations using "FLUENT". From the simulations one can clearly see 3 different regions, the entrainment region, in which most of the entrainment takes place, in this region the velocity and density profiles is almost uniform. The second is the roller region - in which almost no entrainment takes place. At the end of that region, the velocity profile is appreciably deviates from the flat one. In the third region, a post jump between the jump and the downstream obstruction, the velocity profile is starting to change back into a uniform profile. The results of the one-dimensional model and the FLUENT simulations are confirmed using a flow visualization experiment