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Drag and lift forces acting on a spherical water droplet in homogeneous linear shear air flow

Published online by Cambridge University Press:  14 October 2021

Ken-Ichi Sugioka  and
Satoru Komori
Ken-Ichi Sugioka
Affiliation:
Department of Mechanical Engineering and Science and Advanced Institute of Fluid Science and Engineering, Kyoto University, Kyoto 606-8501, Japan
Satoru Komori
Affiliation:
Department of Mechanical Engineering and Science and Advanced Institute of Fluid Science and Engineering, Kyoto University, Kyoto 606-8501, Japan
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Abstract

Drag and lift forces acting on a spherical water droplet in a homogeneous linear shear air flow were studied by means of a three-dimensional direct numerical simulation based on a marker and cell (MAC) method. The effects of the fluid shear rate and the particle (droplet) Reynolds number on drag and lift forces acting on a spherical droplet were compared with those on a rigid sphere. The results show that the drag coefficient on a spherical droplet in a linear shear flow increases with increasing the fluid shear rate. The difference in the drag coefficient between a spherical droplet and a rigid sphere in a linear shear flow never exceeds 4%. The lift force acting on a spherical droplet changes its sign from a positive to a negative value at a particle Reynolds number of Rep ≃ 50 in a linear shear flow and it acts from the high-speed side to the low-speed side for Rep ≥ 50. The behaviour of the lift coefficient on a spherical droplet is similar to that on a stationary rigid sphere and the change of sign is caused by the decrease of the pressure lift. The viscous lift on a spherical droplet is smaller than that on a rigid sphere at the same Rep, whereas the pressure lift becomes larger. These quantitative differences are caused by the flow inside a spherical droplet.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 570 , 10 January 2007 , pp. 155 - 175
Copyright
Copyright © Cambridge University Press 2007

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