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Research Papers

Deformation of a Droplet in a Channel Flow

[+] Author and Article Information
Ebrahim Shirani

Mechanical Engineering Department, Isfahan University of Technology, Isfahan 84156, Iraneshirani@cc.iut.ac.ir

Shila Masoomi

Mechanical Engineering Department, Isfahan University of Technology, Isfahan 84156, Iran

J. Fuel Cell Sci. Technol 5(4), 041008 (Sep 09, 2008) (8 pages) doi:10.1115/1.2930774 History: Received October 30, 2006; Revised October 18, 2007; Published September 09, 2008

Formation of droplets especially in microchannels, micro-electro-mechanical systems (MEMS) and polymer electrolyte membrane fuel cells and their effects on the performance of these devises, as well as scientific aspect of the droplet behavior in the fluid flow motion, makes the subject of the droplet deformation and motion an attractive problem. In this work, we numerically simulate the deformation of a drop of water attached to the wall of a channel flow using full two-dimensional Navier–Stokes equation and the volume-of-fluid method for capturing the interface. The effects of channel inlet velocity, the density and viscosity of the surrounding fluid, and the surface tension coefficient on the flow structures both inside and outside of the droplet as well as the deformation of the droplets are examined. Several test cases, which cover rather wide range of the Reynolds and capillary numbers, based on the surrounding fluid properties and the diameter of the droplet are performed. The Reynolds number, Re, range is from 24 to 1800 and the capillary number, Ca, is from 0.014 to 0.219. It is found that the droplet shape changes and depending on the capillary and Reynolds numbers, it eventually reaches an equilibrium state when there is balance between the surface tension, inertia, and the viscous forces. It is also found that the deformation of the droplet does not depend on the capillary numbers, when Ca is small, but it is a strong function of Ca, when it is large.

Copyright © 2008 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

Schematic diagram of attached droplet in a channel

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Figure 2

Initial and the final equilibrium shapes of a droplet for Case 1

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Figure 3

Maximum length from the center of a drop to a drop surface interaction for Case 1

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Figure 4

Flow configurations at t=20ms, for Case 8 using different computer codes. (a) Surfer code and (b) Linux code.

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Figure 5

Pressure configurations along vertical axis at t=20ms, for Case 8 using different computer codes

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Figure 6

Flow configurations at t=20ms, for Case 1

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Figure 7

Flow configurations at t=20ms, for Case 2

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Figure 8

Flow configurations at t=20ms, for Case 3

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Figure 9

Droplet shape at t=0 and t=20ms for Case 1

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Figure 10

Droplet shape at t=0 and t=20ms for Case 2

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Figure 11

Droplet shape at t=0 and t=20ms for Case 3

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Figure 12

Flow configurations at t=20ms, for Case 4

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Figure 13

Flow configurations at t=20ms, for Case 1

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Figure 14

Flow configurations at t=20ms, for Case 5

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Figure 15

Droplet shape at t=0 and t=20ms for Case 4

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Figure 16

Droplet shape at t=0 and t=20ms for Case 1

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Figure 17

Droplet shape at t=0 and t=20ms for Case 5

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Figure 18

Flow configurations at t=20ms, for Case 1

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Figure 19

Flow configurations at t=20ms, for Case 6

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Figure 20

Flow configurations at t=20ms, for Case 7

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Figure 21

Droplet shape at t=0 and t=20ms for Case 1

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Figure 22

Droplet shape at t=0 and t=20ms for Case 6

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Figure 23

Droplet shape at t=0 and t=20ms for Case 7

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Figure 24

Flow configurations at t=20ms, for Case 1

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Figure 25

Flow configurations at t=20ms, for Case 8

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Figure 26

Flow configurations at t=20ms, for Case 9

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Figure 27

Droplet shape at t=0 and t=20ms for Case 1

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Figure 28

Droplet shape at t=0 and t=20ms for Case 8

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Figure 29

Droplet shape at t=0 and t=20ms for Case 9

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Figure 30

Characteristic length scale ratio as a function of capillary number

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