Vapour bubble collapse in isothermal and non-isothermal liquids

Abstract

The motion of a vapour bubble in a subcooled liquid is studied numerically assuming axial symmetry but allowing the surface to deform under the action of the fluid dynamic stress. The flattening of the bubble in the plane orthogonal to the translational velocity increases the added mass and slows it down, while, at the same time, the decreasing volume tends to increase the velocity. The deformation of the interface also increases the surface area exposed to the incoming cooler liquid. The competition among these opposing processes is subtle and the details of the condensation cannot be captured by simpler models, two of which are considered. In spite of these differences, the estimate of the total collapse time given by a spherical model is close to that of the deforming bubble model for the cases studied. In addition to an isothermal liquid, some examples in which the bubble encounters warmer and colder liquid regions are shown.