Improvement of Bubble Model in High Void Fraction for Cavitating Flow Simulations

Abstract

One of the cavitation models for cavitating flow simulations is the bubble dynamics based method (bubble model). In a typical bubble dynamics based method, the Rayleigh–Plesset equation is solved for determining the volumetric motion of a bubble. It is derived for a single bubble in uniform fluid, and thus, is not adequate for a bubble in high void fraction fluid. Therefore, in the existing bubble dynamics based model, high void fraction fluid has not been treated as far as utilizing the Rayleigh–Plesset equation is concerned. In this paper, a bubble dynamics model treating high void fraction region is proposed. The present model has a threshold between low and high void fraction. Below the threshold, Rayleigh–Plesset equation is solved. Above the threshold, the second derivative of temporal difference of a bubble radius is set to be zero when the bubble is expanding, and Rayleigh–Plesset equation is again solved when the bubble is shrinking. For computational example, flow around Clark-Y11.7% and NACA0015 is calculated for validation of this approach and compared with experiment and the old bubble dynamics based method.