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[rkoomul]

Hi,

I am trying to generate a sweep mesh for a wing configuration with flaps and slat in a wind tunnel and having trouble with inflation mesh for the boundary layer. The wing geometry is created by extruding the airfoil shape in the z-direction. The computational domain is created by a "Boolean subtract" operation of the wing from a box (created using primitive shapes). 

 

Since I am using a sweep mesh, I set the source face used for sweep as the scoping geometry for inflation and the boundary for inflation as the edges of the airfoil.  I would like to get a y+ value of 0.5. So, I set the inflation option as “first layer thickness” and set the “first layer height” as 6.0E-06 m (based on flat plate analysis).  I also defined a parameter for the wing rotation based on the angle of attack.  For some angle of attacks, it generated very good meshes. However, for some angle of attacks, it created arbitrary mesh crossings in the middle of the boundary layer mesh, where there is not much change in the geometry (see the attached images) and didn’t complete mesh generation.

I tried different growth rates, smoothing levels, number of layers, etc.  None of them seems to help.  Any suggestions to fix this issue will be greatly appreciated. The surface on which I am generating the boundary layer mesh is planar, since it is created from a primitive shape (box), and the wing is an extruded shape. I am using Ansys Version 2020 R1.

Thank you.

[Rob]

It looks like something has corrupted on the surface. Can you put a tet mesh on the volume? I want to see if that works, and if not what happens. 

[rkoomul]

Thank you for the suggestion. ANSYS mesher was able to generate a tetrahedral mesh.  However, the number of elements is very large (close to 22 million).  Also, it generated boundary layer meshes only on some part of the body (see the attached images).  To generate tetrahedral mesh, I removed the sweep mesh option, set the scope of the inflation as the entire domain, and the boundary for inflation as the wing surface.

[Keyur Kanade]

First geometry in meshing looks corrupt. Can you please increase facet quality in DM using Tools - Options - Graphics. 

Next in meshing - I can see there is lot of jump from edge to surface mesh. I suspect you might have used 'Mechanical' as physics preference. If so, please use 'CFD' as preference. 

Make sure that you have selected all faces for inflation.

 

Regards,

Keyur

 

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[rkoomul]

Thank you Keyur.  I changed the quality measure in DM from 5 to 10. But, it didn't make any difference. 

The settings that I used in the mesher were, CFD as the "Physics Preference" and Fluent as the "Solver Preference".  Regarding surfaces for inflation, I used Named Selection for the boundaries and selected the wing surface.   

How do I check if the geometry is corrupted? I created the wing geometry in Spaceclaim using extrusion (pull overation) and exported it as a STEP file.  I imported it into DM and used a Boolean subtract operation from a primitive shape (box) to get the computational domain.

I would like to use Sweep mesh (similar to the one explained at the beginning of this thread) for this configuration, since the configuration is an extruded airfoil shape.

Thanks.

 

[Keyur Kanade]

I would suggest you to do all operations in SpaceClaim. 

Create box shape in SpaceClaim and then use Combine tool to subtract. 

Once you are done with SpaceClaim operations, select geometry in structure tree -- right click -- use Check Geometry. This would show you if geometry has any errors. If geometry has any errors, you will need to fix them in SpaceClaim. 

Once geometry is ready in SpaceClaim, please transfer it to Workbench Meshing. You do not need DM as intermediate step. 

You will find lot of videos on the same on youtube. 

Regards,

Keyur

 

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