Microgravity experiments on dual vapor bubbles of self-wetting fluid

A series of microgravity experiments on dual vapor bubbles of self-wetting fluid (dilute 1-butanol aqueous solution in the present study) have been conducted at JAMIC (Japan Microgravity Center). The analysis of tracer particles around two adjacent vapor bubbles clearly showed the Marangoni flow directing toward the bubble/heater interface which prevented the bubble coalescence. On the other hand, ordinary fluid (CFC-113 in the present study) showed a rather strong Marangoni flow of the opposite direction, which enhanced the bubble coalescence.