Researches on two-phase flows around a hydrofoil using Shan-Chen multi-phase LBM model

Abstract

In this paper, the Shan-Chen-type multiphase lattice Boltzmann model was proposed to investigate two-phase flows around a hydrofoil. In the model, The Shan-Chen force accounts for the attraction force calculated over nearest neighbours of the pseudopotential function, which is employed to mimic the molecular interactions that cause phase segregation. Firstly, the lattice Boltzmann model was validated by the liquid flows around a hydrofoil by means of comparison of drag coefficients and the Shan-Chen model was validated by the Laplace law. And then aiming at various existing bubbles of different radii preplaced above the hydrofoil leading edge, the evolution of gasliquid two-phase flows was successfully reproduced based on heterogeneous cavitation assumption. The shedding bubbles become smaller and smaller downstream the hydrofoil, and finally collapse behind the tailing edge. The inter-particle forces are analyzed based on the two-phase flow density, and then the corresponding pseudo-velocity distribution is predicted near the phase interface. Then the attached cavitating flows is studied based on homogeneous cavitation assumption. It can be concluded that the attached cavitation occurs and evolves under some reasonable conditions. It can be found that that a small change in the velocity or pressure will bring great influence on the bubble size. All the above-analyses demonstrate that Shan-Chen multiphase model can capture well the inter-phase force and can be treated as an alternative potential approach for predicting cavitating flows.