I have a 50um square channel producing a droplet of size 100um in dia. The density ratio between continuous to disperse media is 1.89. I would like to know how gravity plays a role in trapping the droplet.
Can elaborate a little more on your system? A setup picture would be really helpful.
Best
I hope things explains. In the picture case the droplet gets into the well bottom. Apply the same to a 50um (width and height) channel with 100um (cubic) well size.
This is certainly helpful! So I assume you apply a constant flow as well.
One way of evaluate gravity is by the means of the Bond number. Then you can plot the Bond number versus the other important non-dimensional numbers of you system to get a first gasp of how it evolves.
Hope this helps, best
Thank You Stefan Zitz. Can you tell me if I have to consider the characteristic length in the Bond Number and the droplet is a plug as shown in the picture, should we still consider plug length? OR consider its diameter of the droplet, when it becomes spherical?
Well instead of a characteristic length the volume should be better suited.
There is this paper by Sbragaglia:
Article Sliding drops across alternating hydrophobic and hydrophilic stripes
There they show how to compute the Bond number based on the volume of the drop. It's above equation one in the paper.
Best
Hi Stefan - I have another connecting question. If the bond number is less than 1, we say gravitational effects are not dominant. We notice trapping happens even with bond number less than 1 in some literature. How should we conclude on this? Pls help
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