Bubble sweeping and interactions on wires during subcooled boiling

Multi-bubble dynamics on a heated wire are modeled with a phenomenological model of the temperature distributions around the bubbles and the forces acting on the bubbles. The model calculates the heat transfer from the wire to the bubble and the temperature distribution in the wire. The model balances the Marangoni force, the drag force, and the contact line force acting on the bubble to predict the bubble velocities. The predicted velocities and the predicted interactions agree well with experimentally observed bubble dynamics. The predictions show that when a moving bubble approaches a stationary bubble at moderate superheats, the reduced wire temperatures around the stationary bubble cause the moving bubble to slow and reverse direction before colliding with the stationary bubble. At higher superheats, the bubbles coalesce. The model also shows that when two bubbles approach each other from opposite directions, they will collide and coalesce at lower superheats than when only one bubble is moving because the temperature gradients in front of the moving bubbles are much steeper than in front of a stationary bubble; thus, moving bubbles do not slow much before coalescing.