On the nonspherical collapse and rebound of a cavitation bubble

Abstract

The behavior of a cavitation bubble adjacent to a rigid wall is studied numerically with the boundary integral method described in Zhang, Duncan, and Chahine [J. Fluid Mech. 257, 147 (1993)]. In the previous work, the pressure inside the bubble was held constant (this is referred to herein as the empty bubble case). In the present calculations, an internal gas pressure, which is a function of the bubble volume, is included in the model. The present results are qualitatively similar to those in the empty bubble case in several ways: a wall-directed reentrant jet is formed in the later phase of the collapse; this jet impacts with the side of the bubble closest to the wall creating a toroidal-shaped bubble; and a shear layer develops along the impact interface. However, unlike the empty bubble, whose volume decreases monotonically to zero at the end of the collapse, the present gas-filled bubble reaches a minimum volume and then, due to its high internal gas pressure, begins to grow again (rebound). In the empty bubble case, the hydrodynamic pressure on the wall rises rapidly at the end of the calculation making it impossible to compute the maximum value of the pressure. In the present calculations, the pressure on the wall is found to reach a maximum value when the bubble starts to rebound. This timing of the pressure peak is in agreement with the experimental data of Tomita and Shima [J. Fluid Mech. 169, 535 (1986)] and Kimoto [International Symposium on Cavitation Research Facilities and Techniques (American Society of Mechanical Engineers, New York, 1987), Vol. 57, pp. 535–564], as are the orders of magnitude of the maximum pressures. Direct comparison with the numerical results of Best [J. Fluid Mech. 251, 79 (1993)] are also presented. Large differences in bubble shapes and flow fields are found.

Interaction of underwater explosion bubble with complex elastic-plastic structure

“…Best [19] introduced an adjacent branch cutting technology, using boundary integral on the bubble surface and the cutting surface, which needs special treatment when cutting the bubble surface and is not easy to be spread. Zhang and Duncan, et al [20,21] defined a layer to detach the jet region and its ambient region at the toroidal phase during the simulation process. The layer moves with the fluid as a vortex surface.…”

Modelling cavitation erosion using fluid–material interaction simulations

“…We consider an initially spherical bubble of radius 50 mm, located at a distance of X ¼ 1.5 mm from a flat material surface and subject it to a time-varying pressure field as represented in figure 2 and expressed as follows: This imposed pressure variation is different from that used in many classical studies on bubble collapse near a wall and where a bubble with a maximum radius is suddenly subjected to a pressure higher than the internal pressure such as in [71][72][73][74]. Here, bubble growth is included (this allows one to include standoff distances smaller than the bubble maximum radius and covers a large range of applications), and the time-varying pressure field represents for example the pressure encountered by a bubble nucleus captured in the shear layer of a cavitating jet.…”

Comparison between the 3D numerical simulation and experiment of the bubble near different boundaries

“…To solve this problem, Wang et al [6,10] converted the bubble from a single-connected to multi-connected domain with a domain-cut procedure and arranged a vortex ring to simulate the bubble's toroidal phase. Therefore, it was only needed to make the vortex ring inside the bubble instead of tracing the motion of vortex sheet as Zhang et al [8,9] did. Zhang et al [7] developed the vortex ring model to be a 3D vortex ring model.…”

“…Secondly, a circulation flow is formed after the jet. Zhang et al [8,9] defined a layer which moves with the fluid as a vortex sheet to separate the jet region and its ambient fluid region. However, it is very difficult in tracking, especially in 3D problems because the deformation of the layer cannot exceed the bubble surface.…”