Influence of bubble-particle distance on the dynamic behaviors of a cavitation bubble near a particle

Cavitation and silt-erosion often co-exist, causing severe damage on fluid machinery. In this paper, the dynamic behavior of a cavitation bubble near a fixed spherical particle is numerically studied, with the focus on the influence of the stand-off distance gamma on the bubble collapse morphology, micro-jet velocities and pressure on the particle. With the increase in the value of gamma, the bubble profile in the collapse stage exhibits three distinct characteristics: Mushroom-shaped, pear-shaped and spherical-shaped, and the corresponding micro-jets are identified as contact jet, non-contact jet, and long-distance jet. All studied distances can be categorized into three ranges, and the typical cases in each range are demonstrated. The maximum jet velocity Vmax and the maximum pressure difference between the upper and the bottom of the particle Delta pmax show the highest peak at gamma = 0.9, with Vmax up to 180 m/s and Delta pmax up to 10.8 MPa.