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-   -   getting airfoil surface to be recongized for tri mesh (http://www.cfd-online.com/Forums/ansys-meshing/88890-getting-airfoil-surface-recongized-tri-mesh.html)

josip76 May 29, 2011 18:12

getting airfoil surface to be recongized for tri mesh
 
Hi im using ICEM and i want to create a tri mesh around an airfoil. so i imported my airfoil points (which automatically created my curves and airfoil surface for me). I then created my farfield and made a surface inside its bounds called fluid. However I cant get the fuid surface to see my airfoil. I tried using the trim surface function specifically the by curve method found in the "create/modify surface" tab under the "geometry" tab. However this created a strange looking cut of the airfoil (not matching the airfoils edges). Even still when i created my mesh it ignored the airfoil. Can someone please explain how to do this.

I've watched the videos posted on youtube for tetra meshing by simon and have read the posts such as "Complex 2D meshing on icem" in this forum but am still unable to get started please help me or explain to me where i can go to find this information. My deadline for this project is approaching quickly.

Thanks for helping

alastormoody11 May 30, 2011 06:43

Hi,

Are you sure that curve generated during the import is a single curve passing through all the points?

When you are splitting using the curve option just check whether some part of the curve is left out.

Also what do you mean airfoil surface? Why didn't u delete it?

Can you post some images?

josip76 May 30, 2011 13:01

Hey alastormoody11,

So when i enter my geometry I do so as formatted point data and the settings are such that ICEM splines the points creating two curves one for the top and the other for the bottom as well as a surface between these points. So a close up view of the airfoil with the surfaces coloured looks like this:

http://dl.dropbox.com/u/29394155/1.JPG

The surface of the airfoil really serves no purpose so as u said i deleted it and to ensure my curves are one i went to “Geometry/Curves/Concatenate Curves” in the tool-bar and joined the two curves into one. Then created the fluid surface which looks like this (close up of airfoil):

http://dl.dropbox.com/u/29394155/2.JPG

Following this i went to “Geometry/Repair Geometry/Build Topology” and applied. I did this because from what i understand this enables the fluid surface to see my airfoil curve. Now when I select the surface inside the airfoil curves it shows this:

http://dl.dropbox.com/u/29394155/3.JPG

Obviously when it built the topology it did not match the edges of the curve. Following this i trimed the airfoil from the fluid surface using “Geometry/Surfaces/Trim Surface” using the by curve method. I selected the fluid surface inside the airfoil and the airfoil curve and clicked apply. Then I enabled the mesh by first setting my Shell Meshing Parameters, then Part Mesh Set-up, then under Surface Mesh Setup I clicked first on the fluid and set my parameters then I clicked insiude the airfoil curves and set Mesh Type to None. When the mesh was computed for all geometry it gave this:

http://dl.dropbox.com/u/29394155/4.JPG

You can see the outline of the airfoil (though not of the correct airfoil geometry) but the meshing ignored the airfoil boundary altogether. So I am wondering how to get the airfoil boundary to be respected durring meshing and only mesh the fluid.

Thanks for all your help

PSYMN June 6, 2011 14:50

It looks like it trimmed things properly... But perhaps with too low a tolerance... Go back into settings and refine your tri-tolerance from 0.001 down to 0.0001 and try the trim operation again...

You should then delete the surface within the airfoil and then mesh...

Note, in your final image, the mesher did respect the boundary of the airfoil (as much as the mesh resolution would allow), you just didn't want it to mesh inside and out...

josip76 June 9, 2011 22:48

Thanks for the sugestion of increasing the tolerance it worked out well the cut now more closely resembles the airfoil shape and i gotten the mesh to resemble more closely what i wanted. again thanks for your help although for my problem I've actually decided to go back to using a hex mesh when i get some more time im gonna come back and retry the problem using tri.


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