Numerical analysis of the dynamics of moving vapor bubbles

Abstract

Bubbles have been observed rapidly sweeping along very fine heated wires during subcooled nucleate boiling with jet flows emanating from the tops of the vapor bubbles. This paper analyzes the physical mechanisms driving the bubble and the jet flows from the tops of these moving bubbles. The flows are analyzed by numerically solving the governing equations for the velocity and temperature distributions around the bubble and the heated wire as the bubble moves along the wire. The bubble motion is due to the non-uniform temperature distribution in the liquid and in the wire caused by the bubble as it moves along the wire. The flow is driven by the horizontal Marangoni flow induced by the temperature difference across the bubble which thrusts the bubble forward. Comparisons with experimental observations suggest that the condensation heat transfer at the bubble interface is restricted by non-condensable gases that increases the surface temperature gradient and the resulting Marangoni flow.