Abstract
Studying the flow characteristics of bubbles in a narrow gap is an important problem related to bearing cavitation and gas–liquid two-phase flow. In this paper, we present a modified three-dimensional multi-relaxation-time pseudo-potential model for large density ratio multiphase phenomena. The accuracy of the model is verified by the Maxwell construction, Laplace law, and Rayleigh–Plesset equation. The influence of the force scheme parameter and the dimensionless relaxation time on the thermodynamic consistency of the model is analyzed. The results show that the three-dimensional lattice Boltzmann pseudo-potential model proposed in this paper has good numerical stability in simulating multiphase phenomena. Furthermore, the cavitation bubble collapse process between parallel rigid walls is simulated by the proposed model. The collapse process obtained by the present method agrees well with the experimental result. The different orientations for the bubble to the wall exert a significant influence on the variation of the pressure field, velocity field, and evolution of maximum pressure and micro-jet velocity. During the cavitation bubble collapse process, the pressure and the velocity at the collapse point will increase instantaneously, and the orientation for the bubble to the wall is a key factor to determine the collapsed form of the cavitation bubble. The results verified the practicability of the addressed model to study the collapse of three-dimensional cavitation bubbles in the presence of parallel rigid walls.
Highlights
Cavitation refers to the process of formation, growth, and collapse of vapor or gas cavities in the liquid where the local pressure drops below a critical value
When ε = 0.118 95, the simulation results of lattice Boltzmann method (LBM) are in good agreement with the theoretical values, and the coexistence maximum density ratio reaches 750, which proves that the proposed MRT pseudo-potential model with an improved external forcing scheme can achieve thermodynamic consistency and a large density ratio by adjusting parameter ε
When 0.42 ≥ β > 0, the cavitation bubble evolution process will be consistent with Fig. 14(c), the cavitation bubble deformation will not be affected by the rigid walls, and the cavitation bubble remains spherical throughout the collapse process
Summary
Cavitation refers to the process of formation, growth, and collapse of vapor or gas cavities (cavitation bubbles) in the liquid where the local pressure drops below a critical value. Previous studies have shown that boundaries (such as rigid walls, free liquid surfaces, and gas–liquid interfaces) have important effects on the collapse of cavitation bubbles, the development of cavitation shock waves, and the formation of micro-jets. Scitation.org/journal/adv them, the study of the cavitation bubble collapse between parallel rigid walls is a very important problem related to bearing cavitation and gas–liquid two-phase flow. It is worthwhile to mention that most of the recent numerical simulations of the cavitation process with complex topography with LBM are based on two-dimensional models, and only a small part of the literature concerned simulations of the collapse process of cavitation bubbles under simple boundary conditions in three dimensions.. A three-dimensional modified large density ratio multi-relaxationtime (MRT) pseudo-potential model is adopted to investigate the collapse process of cavitation bubbles between parallel rigid walls.
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