Comment on “Effect of liquid temperature on sonoluminescence”

Abstract

It has been suggested that bubble-wall velocities cannot exceed the sound speed in the liquid at the bubble wall [K. Yasui, Phys. Rev. E 64, 016310 (2001).10.1103/PhysRevE.64.016310]. Here we show that this upper bound was derived omitting the partial derivatives with respect to time, i.e., assuming that the flow was in the steady state. For collapsing bubbles, however, the steady-flow assumption requires justification, as the partial time derivatives appear to have the same orders of magnitude as the other terms in Euler's and the continuity equations. Furthermore, numerical solutions of the hydrodynamic equations with a hyades hydrocode yielded supersonic velocities in the liquid at and near the collapsing bubble. We also show the spatial distributions of pressure, density, sound speed, and mass flux density around the supersonically collapsing bubble.

High-speed video microscopy and numerical modeling of bubble dynamics near a surface of urinary stone

“…The impact of the jet on the stone produces a hydraulic shock with water-hammer pressure / qcv jet , where q is the density and c is the speed of sound. [21][22][23] Both the density and the speed of sound grow with pressure, 16 but even at atmospheric pressure (q % 1000 kg/m 3 and c % 1.5 km/s) the impact of a jet with v jet $1 km/s produces a hydraulic shock of $1.5 GPa.…”

“…For modeling, we solved the multicomponent Euler equations using a two-dimensional (2 D)-axisymmetric code with adaptive time step and mesh refinement algorithms for fine resolution of the gas-liquid interface and shock fronts. 8,9 The use of a 2 D code instead of a one-dimensional (1D) spherical model [10][11][12][13][14][15][16] was motivated by the present and previous observations showing that oscillations of microbubbles can be highly nonspherical. 2,[17][18][19][20][21][22][23][24][25] Hsiao and Chahine 26 modeled a shelled microbubble subjected to one cycle of 2.5-MHz ultrasound at 1 MPa.…”