Lattice Boltzmann simulation of cavitating bubble growth with large density ratio

Abstract

Natural cavitation is defined as the formation of vapor bubbles in a flow due to the pressure falling below the liquid’s vapor pressure. The inception of the cavitation bubble is influenced by a lot of aspects, such as impurities, turbulence, liquid thermal properties, etc. In this paper, the exact difference method (EDM) and the Carnahan–Starling real-gas equation of state (EOS) are coupled in the Shan–Chen multiphase lattice Boltzmann model, which is validated as being suitable for simulating high liquid/vapor density ratio multiphase flows. The 2D cavitation “bubble” growth is simulated under a quiescent and shear flow in the inception stage. Besides yielding the large density ratio, the real-gas EOS also leads to apparently different compressibilities for liquid and vapor. The results agree with Rayleigh–Plesset predictions much better than those of a previous publication [X. Chen, Simulation of 2D cavitation bubble growth under shear flow by lattice Boltzmann model, Communications in Computational Physics 7 (2010) 212–223]. In the meantime, a comparison is conducted for single-bubble behavior under different shear rates, with reduced temperature T / T c r i t i c a l = 0.6891 and relaxation time τ = 1.0 . The simulation results show that the cavitation bubble deformation is consistent with the bubble dynamics, D ∝ Ca , where D and Ca are the bubble deformation and the capillary number respectively. The shear rate hardly influences the bubble growth rate.