Coalescence of drops on the free-surface of a liquid pool at elevated temperatures

Kirar, Pavan Kumar and Alvarenga, Kathryn and Kolhe, Pankaj and Biswas, Gautam and Sahu, Kirti Chandra (2020) Coalescence of drops on the free-surface of a liquid pool at elevated temperatures. Physics of Fluids, 32 (5). 052103. ISSN 1070-6631

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Abstract

Abstract View references (38) The coalescence dynamics of ethanol drops injected from a needle on the free-surface of an ethanol pool maintained at a higher temperature than the drop is experimentally studied using a high-speed imaging system. The drop is always kept at 25 °C, and the temperature of the ethanol pool is varied using a heater. The coalescence behavior depends on the size of the drop, the height of the needle tip from the free-surface, and the temperature of the ethanol pool. A parametric study is carried out by varying these parameters. The drop exhibits a residence period at low impact velocity, when it floats on the free-surface before the coalescence begins. Subsequently, the complete coalescence and partial coalescence dynamics are observed for different sets of parameters considered. It is found that increasing the temperature of the ethanol pool reduces the residence time of the drop. This phenomenon is explained by analyzing the forces acting on the drop and the capillary waves generated due to the temperature gradient between the drop and the ethanol pool. During partial coalescence, we also observed that the diameter of the daughter droplet decreases as the size of the primary drop and pool temperature are increased. As expected, due to the gravity effect, increasing the size of the drop also decreases the residence time. A regime map designating the complete coalescence and partial coalescence dynamics is plotted in the pool temperature and drop impact height space.

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IITH Creators:
IITH CreatorsORCiD
Sahu, Kirti Chandrahttp://orcid.org/0000-0002-7357-1141
Item Type: Article
Uncontrolled Keywords: Coalescence,Dynamics,Ethanol,Needles,Sailing vessels
Subjects: Chemistry
Chemical Engineering
Chemical Engineering > Fluid Mechanics
Divisions: Department of Chemical Engineering
Depositing User: . LibTrainee 2021
Date Deposited: 06 May 2021 06:59
Last Modified: 06 May 2021 06:59
URI: http://raiithold.iith.ac.in/id/eprint/7768
Publisher URL: http://doi.org/10.1063/5.0007402
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