Aggregation of bubbles by thermocapillary flow

Abstract

Thermocapillary flow near adjacent bubbles on heated surfaces explains bubble aggregation on a hot surface. The bubbles pump fluid away from the heated surface; this action draws liquid near the wall laterally toward the bubble. Bubbles mutually entrain each other in this flow pattern and aggregate. Experimentally, it has been found that pairs of bubbles placed near the hot surface aggregated; if the gradient was reversed, they separated. Theory based on thermocapillary flow provides the correct scaling and reasonable agreement with experimental data for approximately equal-sized bubbles.