Thermocapillary flow of two bubbles in a close proximity

The investigation of thermoconvective flows is of fundamental interest in view of various engineering applications. On Earth, temperature gradients cause fluid density variations, which lead to flows driven by buoyancy forces. In weightlessness buoyancy effects vanish. This circumstance represents a major advantage regarding space processing. The production of homogenious two-phase materials with large density differences becomes possible due to the absence of convection and sedimentation, Hermann et al.. Nevertheless, bubbles occur during the solidification process caused by soluble gases within the melt component. Bubbles represent serious defects in crystals and alloys and reduce the strength of the material and limitate the material properties. Additionally, bubbles migrate to the container walls and possess the capability to drive strong thermocapillary convection. The thermocapillary convection of two bubbles in a close proximity under a heated wall is studied experimentally.