Thermal delay of drop coalescence

2017/11/08 by Michela Geri, Bavand Keshavarz, Gareth H. McKinley +1 · 1 citation
Engineering · #Electrohydrodynamics and Fluid Dynamics #Fluid Dynamics and Heat Transfer #Innovative Microfluidic and Catalytic Techniques Innovation

paper · pdf · doi:10.1017/jfm.2017.686

Abstract

We present the results of a combined experimental and theoretical study of drop coalescence in the presence of an initial temperature difference \unicode[STIX]x0394T₀ between a drop and a bath of the same liquid. We characterize experimentally the dependence of the residence time before coalescence on \unicode[STIX]x0394T₀ for silicone oils with different viscosities. Delayed coalescence arises above a critical temperature difference \unicode[STIX]x0394T_c that depends on the fluid viscosity: for \unicode[STIX]x0394T₀>\unicode[STIX]x0394T_c , the delay time increases as \unicode[STIX]x0394T₀^2/3 for all liquids examined. This observed dependence is rationalized theoretically through consideration of the thermocapillary flows generated within the drop, the bath and the intervening air layer.

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