Learning Forum

[Peter Felbinger]

Hello folks,

i have a problem for the integration of surface tension and contact angle in my simulation.

I have a small cylinder that rotates around a axis with 900rpm. The fluid is simulated with a Level Set-VOF. I have two different fluids A and B.

A has a surface tension of 0.072 N/m and a contact angle with the wall of 102.1°

B has a surface tension of 0.049 N/m and a contact angle with the wall of 57°

These values are put in the phase interaction tab and in the wall boundary tab

When i run the two simulations and plot the phase fraction of water, the results look identical (left is fluid A, right is fluid B).

Do i miss something that i have to define?

[Rob]

It looks like you set wall adhesion, otherwise you'd not see the free surface distortion. How well refined is the mesh?

[Peter Felbinger]

Hello Rob,

thank you for your reply.

Yes i set wall adhesion and surface tension force modeling.

The mesh quality is as followed:

The mesh was suffiecient for all previous simulations.

[Rob]

OK, you're looking at cell quality. Mesh quality also includes resolution. So, how many cells are there near the walls? Convergence?

[Peter Felbinger]

I have no inflation layers near the wall.

This is a picture of the residuals:

[Rob]

So, how many cells in the region next to the wall? Please post a volume fraction contour with node values off. 

That's not overly well converged, so I'd be very wary of drawing too many conclusions from the model. 

[Peter Felbinger]

Here is a picture from my volume fraction after i patch the water region.

 

[Rob]

And after it's run? Turn node values OFF. 

[Peter Felbinger]

This is after the simulation

[Rob]

What's the contact angle on the bottom?

[Peter Felbinger]

That should be 102.1° as i specified in the BC

[Rob]

Not sure, does mesh refinement help?