The behaviour of a gas cavity impacted by a weak or strong shock wave

Abstract

Two-dimensional simulations of gas cavity responses to both weak shocks (p ≤ 30 MPa) and strong shocks (p ranging from 500 to 2000 MPa) are performed using a finite volume method. An artificial viscosity to capture the shock and a simple, stable, and adaptive mesh generation technique have been developed for the computations. The details of the shock propagation, rarefaction, transmission and bubble wall motions are obtained from the numerical computations. A weak shock is defined in the present context as one that does not cause liquid jet formation upon impact with the bubble. For this case, a large pressure is created within the gas upon collapse due to rapid compression of the gas, ultimately causing the re-expansion of the bubble. The bubble collapse and re-expansion time predicted by this model agree well with spherically symmetric computations. When impacted by strong shock waves, the bubble will collapse and a liquid jet is formed that propagates through the bubble to the opposite bubble wall. Jet speeds as high as 2000 m s−1 are predicted by this model.

Shock-Wave-Induced Jetting of Micron-Size Bubbles

“…As will be shown in this Letter, bubbles of the size of a few microns, even at moderate pressure amplitudes of 10 MPa, form a liquid jet in the direction of the propagating shock wave, which is in contrast to the findings of the numerical work of Ding and Gracewski [2]. There, shocks waves of 30 MPa did not cause jetting.…”

Prediction of far-field acoustic emissions from cavitation clouds during shock wave lithotripsy for development of a clinical device

“…Consequently, they operated on a time scale that was restricted to the early periods of the cavitation event, before these effects became important [43][44][45]. The advantage of the freeLagrange technique developed for this project [14,15,21] is that it can capture all these aspects, and follow the collapse through to the formation of the blast wave (which dominates the far-field emission from such a cavitation) and beyond.…”

Bubbles with shock waves and ultrasound: a review

“…A typical simulation is shown in figure 7, where the shock wave is modelled as a travelling step pressure. In [41], the code was validated by comparing with the simulation results from previous papers [36,38]. It was found that the BEM code successfully captured the bubble deformation and collapse.…”

“…Their results showed the reflection of shock waves inside the bubbles, and dynamic stress loading on nearby solid materials. In [37], the authors validated their code by comparing with an arbitrary Lagrangian Eulerian (ALE) simulation reported in Ding & Gracewski [38], who used the ALE method to solve the Euler equations for the simulation of a shock wave interaction with an air bubble. Both weak (less than 30 MPa in peak pressure) and strong (up to 2 GPa in peak pressure) shocks were investigated.…”

“…This results in a jet travelling in the direction of the shock wave. Note that the case of figure 7 (done with a BEM) uses the same parameters as those in Ding & Gracewski [38] . Simulation result of the interaction of a pressure pulse of 0.528 GPa (modelled as a step function, i.e.…”