Experimental investigation on evaporation induced convection in water using laser based measurement techniques
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Abstract
Recent studies showed that evaporation of water can induce surface tension gradients along the water surface and ultimately lead to convection, known as Marangoni convection. This study was devoted to visualization and characterization of the evaporation-induced, surface-tension-driven convection in water using laser-based measurement techniques.
The evaporation of water at various low vapor-phase pressures in the absence of buoyancy driven flow was investigated. Strong symmetric convection was observed and its velocity field was measured using stereo particle image velocimetry. The temperature field obtained from using both a thermocouple and planar laser induced fluorescence indicated that no buoyancy driven flow was generated. The strength of the convection was found to be correlated with the evaporation rate of water. In addition, the estimated Marangoni number exceeded the critical value for onset of Marangoni convection. It can be concluded that the observed evaporative convection of water can only be Marangoni convection.