Vapor bubble approaching a superheated wall

Abstract

A three-dimensional numerical study is conducted of a single FC-87 vapor bubble rising in non-uniformly heated FC-87 liquid and interacting with an inclined superheated wall. A complete phase-change model that takes into account the effect of interface heat flux on the local interface temperature is used to capture, in particular, the phase change at the interface during the bubble–wall interaction process. The formation and dynamics of the liquid microlayer (a liquid film tens of microns thick between the bubble and the wall) is computed as a part of the solution. This solution is conducted on adaptive octree grids for improved accuracy and efficiency.The details of the flow and temperature fields during the bubble–wall interaction process are presented with the aid of contours of volume fraction and iso-lines of mixture temperature. Heat transfer rates of the wall, microlayer and wake are quantified and related to overall bubble dynamics. The total wall heat flux enhancement is 6–7 times the precursor value during the initial wall interaction of a single FC-87 vapor bubble, of 1mm initial radius, approaching a 10° inclined plate with 2°C as the maximum superheat. Good overall agreement of bubble dynamics and microlayer thicknesses is observed between the simulations and experiments of Li [22]. This simulation of the approach regime of the bubble–wall interaction on an efficient grid provides the platform and the initial and boundary conditions necessary to study the sliding bubble problem for longer times.