Temperature gradient driven flow experiments of two interacting bubbles on a hot wall

This publication deals with the thermocapillary convection of two bubbles in a close proximity under a heated wall. The resultant toroidal vortex rings of the bubbles interfere and cause a distinctive threedimensional flow pattern. Additionally we observed the penetration depth of this flow configuration in dependence on the bubble spacing. Liquid crystal tracer particles serve for simultaneous flow- and temperature monitoring. This novel method is described in some detail. It is a very helpful tool for analyzing heat and mass transfer in liquids.