Learning Forum

[kumar119]

Dear all, I want to have a better control over AMR (automatic mesh adaption) as I am trying to simulate a VOF problem. The mesh that I want is like the one in black with the red line of interface between the phases. Also, the one I get with the FLUENT VOF adaption scheme, is in green mesh. The controls (options) I am having are also attached in the post here. I have tried each and every combination to control the same, but no success. I have tried "advanced controls" by providing additional refinement layers, still it doesn't work out.
The requirement is such that the mesh adapted layers should not instantly get coarsened, instead it should have some additional layers (say 5 or 6 layers of the same sized cells) as shown in the figure with black mesh, and the same should continue for the next level.
Is there a way that this distance from the interface or the number of fixed sized layers can be confirmed to achieve the desired adaption control/desired mesh as shown.
If there can be some expression also, please help me with some hints how to do so.
Many thanks in advance.

[Rob]

Not really. The image in black looks to be refining based on a criterion other than the interface. Ie it's refined based on the mathmatical position of the red line. If the red line moves as a result of the flow field the mesh won't be updated.

What's wrong with the automatic result? 

[kumar119]

Yes, it might be the case with some mathematical position based, but should move.

It's simply that I want to add some more layer. The default one is not capturing some of the physics near the interface resulting in spurious shape.

[kumar119]

Also, this line is not an artificial line, it's an isosurface of iso-value of VolumeFraction of the liquid = 0.5.

[Rob]

Try using the Additional Refinement Layers under Advanced Controls. 

[kumar119]

Dear sir, I have tried this too, but the same could not produce any additional layers.

This is what I initially thought that this option might work. It gave initial layers, but then after single iteration it disappeared from the updated mesh.

[Rob]

That may be the automatic coarsening as there's no field gradient to prevent that step.