Learning Forum

[buksa]

Hello. I have a question whether it is possible to create a bubble in ansys fluent? I mean creating soap bubbles from a layer of soap, not "injecting". Schematically as in the picture. I have a tube through which air flows. At the end of this tube is a layer of soap, which is to create a bubble. How to create/select such a layer? Are there any models in ansys? The bank is about to rise and fly away. I want to watch when it bursts. Thanks in advance for your help

[Rob]

Have a look at the VOF model. The problem you're going to have is resolving the bubble liquid layer sufficiently to create the bubble, and then show it breaking away without shattering. So, in theory it's possible but the compute requirements are going to be high. 

[buksa]

Do you know how to assume the appropriate thickness of this layer in the geometry? Are there any models of the layer in fluent? 
I did it with the VOF model but without creating the layer in the geometry and the results I got did not meet my expectations.
A "bubble" was created regardless of the boundary conditions at the inlet. And I want to check at what "lowest" air intensity in the tube (in inlet) a soap bubble will form, which will break off.

[buksa]

In reality the layer is nanometer thick, so I would need some kind of model of the coating...

[Rob]

You'd need to patch a layer of bubble liquid. But the thickness will be very small: as you comment it's one nm. Have a look at the Continuity Assumption re scale and Knudsen Number. Also how the VOF model works. For the scale you're looking at I think you'll struggle: the solver isn't designed to work at that scale.