Abstract
A lattice Boltzmann pseudopotential cavitation model with tunable surface tension and large density and viscosity coefficient ratios was used to simulate near-wall cavitation bubble collapse. The influences of the surface tension, bubble–wall distance, and initial pressure difference on the flow field distribution were analyzed, and the relationships between the surface tension and maximum micro-jet and collapse pressure were investigated. The results indicated that a lower surface tension intensifies the deformation of the gas–liquid interface, resulting in a more concentrated micro-jet. In addition, more surface energy is accumulated during cavitation bubble collapse for higher surface tension, strengthening the collapse intensity and increasing the maximum micro-jet velocity and collapse pressure. The time interval between the first and second pressure peaks increases with increasing wall distance. Because of the non-linear attenuation during pressure propagation, the value of the second peak decreases with increasing wall distance. Increasing the initial pressure difference leads to slower growth in the micro-jet velocity and faster growth in the collapse pressure with increasing bubble–wall distance. In addition, increasing the initial pressure difference for the same bubble–wall distance also slows the growth in the micro-jet velocity and increases the growth in the collapse pressure caused by increasing surface tension.
Highlights
INTRODUCTIONA sudden pressure drop or energy input can rupture a liquid, and phase change can occur with the emergence of vapor bubbles. Extremely high pressures, micro-jet velocities, and shockwaves are generated with a cavitation bubble collapse
On the liquid-phase density curve, the simulation results for different surface tension conditions agree well with the theoretical prediction, while on the branch of the gas-phase density, a mild difference exists at T/Tc at different surface tensions
The results indicated that a lower surface tension leads to a more dramatic deformation and produces a cavity with greater curvature when the cavitation bubble collapses in the near-wall region, leading to a more concentrated micro-jet
Summary
A sudden pressure drop or energy input can rupture a liquid, and phase change can occur with the emergence of vapor bubbles. Extremely high pressures, micro-jet velocities, and shockwaves are generated with a cavitation bubble collapse. The Eulerian–Lagrangian model provides the flow field information for the cavitation bubble through the Euler equation and tracks the motion and deformation of the cavitation bubble using a Lagrangian approach Even though this method can obtain better results for cavitation bubble groups, the computational resources required are not insignificant. Peng et al. extended the model to three dimensions and simulated bubble collapse in a narrow gap They introduced a double distribution function thermodynamic pseudopotential model to study the temperature evolution of cavitation bubble collapse in the near-wall region.. Peng et al. introduced the hybrid pseudopotential model to simulate bubble evolution in an infinite domain considering heat transfer and simulated the entire evolution of laser cavitation bubble growth and collapse in an infinite domain Their results are in good agreement with the theoretical analysis of the R–P equation.
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