SENSITIVITY EVALUATION OF EMPIRICAL COEFFICIENTS IN THE CAVITATION MODELS

Cavitating flow is notoriously complex because of the issues of large density jump across the irregularly shaped phase boundary, interaction between phase change, turbulence, and the stiffness in the numerical solution. These issues can be modeled with the aid of the multiphase transport equations with appropriate source terms to regulate the mass transfer between phases. In this paper, a sensitivity analysis of empirical coefficients to access the predictive capability of the existing cavitation models is presented. Three cavitation models are considered. Two empirical coefficients used in each cavitation model are accessed, namely Cdest, and Cprod, that directly affect the evaporation and condensation of phases. The coefficients are non-dimensionalized with the freestream values to have correct dimensional form as the convective terms. The present compressible multiphase Reynolds averaged Navier-Stokes solver employs a preconditioning algorithm. The standard k-e turbulence model with wall functions is employed as the turbulence closure. The governing equations are solved on multi-block structured curvilinear grids. The sensitivity of the computations for turbulent cavitating flows over the axisymmetric bodies to the empirical coefficients are performed. The empirical coefficients in three cavitation models have been successfully calibrated with the experimental data for different flow conditions. The sensitivity analysis indicates that the cavitation flow characteristic as well as the stability of the numerical method be quite sensitive to the model coefficients. To confirm the use of the calibrated model coefficients, the computations of cavitating flow over the Clark-Y hydrofoil is then carried out. The multiphase solver provides overall satisfactory results for the prediction of cavitating flow behavior.