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arXiv · 1809.08668

Post collision hydrodynamics of droplets on cylindrical bodies of variant convexity and wettability

Gargi Khurana·Nilamani Sahoo·Purbarun Dhar
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Abstract

Post impingement morphology and dynamics of water droplets on convex cylindrical surfaces has been explored experimentally. Droplet impact and post-impact feature studies have been conducted on hydrophillic and superhydrophobic cylindrical surfaces. Effects of the impact Weber number and target-to-drop diameter ratio have been studied. The post-impact hydrodynamics have been quantified using the wetting fraction, the spreading factor and nondimensional film thickness at the north pole of the target. The observations reveal that the wetting fraction and spread factor increases with an increase in the impact We and decrease in the target to drop diameter ratio. An opposite trend is noted for nondimensional film thickness at the targets north pole. It is also deduced that the spread factor is independent of the target wettability. The lamella dynamics post spreading has also been observed to be a strong function of the wettability, impact We and the diameter ratio. An analytical expression for temporal evolution of film thickness at north pole of the cylinderical target is derieved. Another theoretical model based on energy conservation for predicting the maximum wetting fraction for variant cylindrical targets in terms of the governing We and Capillary number and the experimental measurements are in good agreement with the theoretical predictions.

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Gargi Khurana, Nilamani Sahoo, Purbarun Dhar. 2018-09-23. Post collision hydrodynamics of droplets on cylindrical bodies of variant convexity and wettability. https://doi.org/10.1063/1.5064799

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