Learning Forum

[samcrameri]

Hey everyone,,

Working on a project at the moment on flow around surfboard fins. the geometry has the solid part of the fin cut out of a larger area (the fluid). 

I need to add an inflation layer to the surface of the fin to capture flow at the wall, however when I create the Inflation layer it gives me the stair stepping error at the trailing edge. The only settings I have to refine the mesh, are the same inflation layers and a edge sizing on the foil profile, and the same face sizing on the faces of the fins to make the inflation areas smaller.

However, it looks as though it won't let the inflation match up the rest of the mesh behind the domain I have created stop the inflation skewing well past the trailing edge creating worse elements. I suppose I'm asking is there an option that will let the inflation remain uniform up to this line? 

Attached are some screenshots of the issue in more detail, if these are confusing I can upload any you are afterInflation layer Settings.

mesh domain around fin base

Stair-Stepping with skewness quality filter.

poorly skewed mesh along trailing edge. (The front fin hasn't been inflated yet that's why there are no poor element there)

[Karthik Remella]

Hello,

Couple of ways you can handle this.

A smaller Gap Factor results in less layer compression and could help to avoid stair-stepping. The Gap Factor can be changed under 'Advanced Options' for Inflation in the global mesh settings (click on Mesh, in the Details of Mesh, expand 'Inflation', set 'View Advanced Options' to Yes). Please see if this works.

Also, try to add a small curvature to your sharp trailing edge. Sometime, this will easy out the creation of inflation layers.

Thanks.

Best,

Karthik 

[samcrameri]

Thanks for that Karthik. 

I will look at the Gap Factor solution, but I have tried adding a curvature at the trailing edge, but the way I have made the geometry prevents it from working correctly.

I have sort of found my own solution to this though. I split the face along the centre line of the foil and extended the inflation along the face it created (see below). I believe this will solve correctly? I have made a contact on the interface, will this make the solver compute the flow as it moved through the interface? or will it split the flow into the four sections 

 

Cheers,

Sam 

[Karthik Remella]

Hello,

Good to know that you were able to resolve the issue. More often than not, decomposing the geometry or using a different way to create your inflation layers works.

You should not have any issues. If you wish you quickly check, please load the mesh file to Fluent and see if all your named selections show up like they are supposed to.

Thanks.

Best,

Karthik