Numerical Modelling of Unsteady Partial Cavities Behind a Backward Facing Step

摘要

This paper presents some calculation results in the cases of steady and non-steady partial cavity. These results are obtained with the commercial Navier-Stokes codes FLUENT and STAR-CD and compared with experimental results. Under cavitation conditions the first code uses a bubbles two-phase model. The second code uses the VOF (volume of fluid) technique to calculate the interface and allows the use of either the barotropic or the bubbles two-phase model. Different arrangements of the three parameters step height, channel confinement and cavitation number are examined. Cavities observed experimentally are compared with that obtained by the calculation. We investigate the ability of the models to reproduce the non-steady behaviours (re-entrant jet thickness, shedding frequencies).