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.