Numerical simulation of unsteady cloud cavitation: a comparative study of compressible mixture models

Abstract

Focused on the unsteady behavior of intensively cavitating water jets numerical analysis is carried out by applying the compressible mixture flow method under assumptions of bubble cavitation and homogenous mixture. Submerged water jets issuing from a sheathed nozzle is treated when the cavitation number σ ≅ 0.1. The periodically shedding of cavitation clouds in submerged water jet is captured acceptably and the core velocity distribution evaluated by numerical simulation agrees with experiment data of PIV approximately. Concerning the effect of flow compressibility estimation, comparison of computation results reveals that it is capable to capture the unsteady behavior of cavitating flow by both the simplified bubble cavitation model and the homogeneous mixture model. However, the homogenous model shows a tendency to estimate gas volume fraction of cavitation clouds excessively. It becomes necessary to evaluate the mixture compressibility by considering the effect of bubble dynamics in modeling intensively cavitating flow. The simplified isothermal bubble cavitation model is demonstrated to be a practical method for treating bubble-liquid flow with intensive cavitation.