Large Eddy Simulations of cavitating tip vortex flows

Artikel i vetenskaplig tidskrift, 2020

In the current study, tip vortex flows are numerically studied by employing Large Eddy Simulation. Wet flow, cavitation inception, and cavitating tip vortex simulations are carried out on an elliptical foil. The mesh resolution requirements for tip vortex prediction are evaluated by employing different mesh resolutions. Two different LES models, Implicit LES and Localized Dynamic Kinematic Model, are utilized to model the sub-grid scale viscosity, and its impacts on the tip vortex prediction. For the wet flow, vortex properties are computed for each resolution and compared with experimental data. Comparisons show that at least 16 cells per vortex radius is required to predict the tip vortex in the near field region. Employed numerical approach is fully capable of capturing the accelerated axial velocity at the vortex core, and shows good agreement with the experimental observations. The analysis of bubble dynamics shows that tip vortex inception strongly depends on the initial bubble radius, especially where the radius is smaller than 50 μm. The predicted azimuthal velocity, the diameter of the cavitating tip vortex, and the velocity flow fields are compared with experimental measurements. The comparisons show that the current numerical approach can provide accurate prediction of tip vortex flows also in cavitating conditions.