Assessment of RANS turbulence models and Zwart cavitation model empirical coefficients for the simulation of unsteady cloud cavitation

Abstract

The numerical simulation of unsteady cavitation flows is sensitive to the selected models and associated parameters. Consequently, three Reynolds Average Navier-Stokes (RANS) turbulence models and the Zwart cavitation model were selected to assess their performance for the simulation of cloud cavitation on 2D hydrofoils. The experimental cavitation tests from a NACA65012 hydrofoil at different hydrodynamic conditions were used as a reference to tune the modeling parameters and the experimental tests from a NACA0015 were finally used to validate them. The effects of near wall grid refinement, time step, iterations and mesh elements were also investigated. The results indicate that the Shear Stress Transport (SST) model is sensitive to near wall grid resolution which should be fine enough. Moreover, the cavitation morphology and dynamic behavior are sensitive to the selection of the Zwart empirical vaporization, F v , and condensation, F c , coefficients. Therefore, a multiple linear regression approach with the single objective of predicting the shedding frequency was carried out that permitted to find the range of coefficient values giving the most accurate results. In addition, it was observed that they provided a better prediction of the vapor volume fraction and of the instantaneous pressure pulse generated by the main cloud cavity collapse.

Numerical Simulation of Cavitation Erosion Aggressiveness Induced by Unsteady Cloud Cavitation

“…m represents the mass transfer rate between the two phases. For the current simulation, the turbulent viscosity, µ t , in Equation 10has been calculated with the SST k-ω model according our previous investigation [31], and µ t has been defined as:…”

“…The solution strategy adopted for the current simulations was based on our previous work [31] where the influence of the numerical setting was investigated in detail. Consequently, a medium-sized mesh of 29,749 elements with y+ values in the boundary layers ranging from 0.1 to 3 with a mean value of 1.2 was used.…”

Analysis of the Formation Mechanism and Evolution of the Perpendicular Cavitation Vortex of Tip Leakage Flow in an Axial-Flow Pump for Off-Design Conditions

“…Cavitation refers to a phenomenon that occurs when the local pressure is less than the vaporization pressure. The cavitation not only induces flow instability, but also has a serious impact on the performance of hydraulic machinery [17][18][19][20]. The tip leakage flow and cavitation significantly reduce the axial flow.…”

Numerical investigation of the cavitation performance of annular jet pumps with different profiles of suction chamber and throat inlet

“…In the past decades, computational fluid dynamics (CFD) has been used in many fields (Akbarian et al, 2018;Aldaş & Yapıcı, 2014;Ghalandari et al, 2019;Mahdi et al, 2019;Salih et al, 2019). Significantly, this method has been demonstrated to be widely feasible in various systems and has also achieved good results (Geng & Escaler, 2019;Mohammad et al, 2019;Mou et al, 2017;Ramezanizadeh et al, 2019). Numerical methods have also been regarded as important for obtaining more information on cavitating flow in jet pumps.…”