Large-eddy simulation of flow around a sphere: Comparing cavitating and non-cavitatingconditions

In this work partial and supercavitation over a sphere at a constant Reynolds number of ۱.۵×۱۰۶ and a broad range ofcavitation numbers (۰.۳۶<σ<۱) was examined. Large eddy simulation (LES) and Sauer mass transfer model were usedto simulate the dynamic and unsteady cavitation around the sphere. Also, the compressive volume of fluid (VOF)method is used to track the cavity interface. The two-phase flow solver of the OpenFOAM package,intephaseChangeFoam is employed. Large-eddy simulation of cavitating flow over the sphere is compared with thenon-cavitating flow at the same Reynolds number. This work provides a thorough understanding of the fluid dynamiccharacteristics of the sphere cavitation such as turbulent kinetic energy, pressure, streamlines and boundary layer. Also,detailed analyses of the instantaneous cavity leading edge and separation point location, vortex shedding, streamwisevelocity fluctuation and evolution of the cavity are reported. We report that cavitation suppresses instability in the nearwake region and delays the three-dimensional breakdown of the vortices. The volume fraction contours of the cavitycloud obtained from the numerical simulations are compared with the experimental data at the same working conditionwith a suitable quantitative accuracy.

Keywords:

Unsteady Cavitation , Sphere , Large eddy simulation (LES) , Wake , Vortical structure