topic Re: Meshing / gap refinement question in CFD Forum

Meshing / gap refinement question

Cnoj — Tue, 13 Feb 2018 16:46:49 GMT

Hi,

When meshing the heat sink model below the depth of the refinement layers in the air gaps is varying across the model. As all my fin gaps are identical I was expecting the refinement layers in them to be identical. What's causing the variation?

Cad model:

I modeled each fin as three solids and each air path as a single solid.

Resulting mesh showing variation in refinement region thickness:

Re: Meshing / gap refinement question

johnsonshiue — Tue, 13 Feb 2018 21:50:36 GMT

Hi! Is this Autodesk CFD? If not, I am not sure what we can do about it.

Many thanks!

Re: Meshing / gap refinement question

Cnoj — Wed, 14 Feb 2018 13:36:46 GMT

Whoops wrong forum.

Re: Meshing / gap refinement question

Cnoj — Wed, 14 Feb 2018 18:45:04 GMT

OK we're in the correct forum now.

Software is Simulation CFD 2105 v15.2

Thanks.

Re: Meshing / gap refinement question

LKania — Wed, 14 Feb 2018 18:56:29 GMT

Refinement layer length scales are dependent (though not exclusively) on local mesh length scales in order to control element skewness within the refinement layers. Though the fin gap geometry is uniform across your model, the mesh length scales local to these fins are not, hence the refinement layers show some variation as well.

Re: Meshing / gap refinement question

Cnoj — Wed, 14 Feb 2018 19:31:02 GMT

Which of the four fin gaps in my pic is closest to optimal? I'm using a fully developed velocity boundary condition to move the (fixed density) air and only interested in how well the fins conduct heat into the air.

Thanks,

Jon

Re: Meshing / gap refinement question

Jon.Wilde — Thu, 15 Feb 2018 10:09:57 GMT

I would go with the left hand side, typically the more the better and you can test this by refining the mesh to see if the results change.

Check this out: Mesh Sensitivity Study.

Does that answer your question?

Re: Meshing / gap refinement question

Cnoj — Thu, 15 Feb 2018 14:48:40 GMT

Do you mean more thicker or more in qty?

Re: Meshing / gap refinement question

Jon.Wilde — Thu, 15 Feb 2018 15:00:06 GMT