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blockMesh,snappyMesh and experimental results for 2D airfoil

Posted April 1, 2013 at 04:17 by skeptik (CFD notes)

A certain Mahdi wrote me via e-mail, that my tetra-mesh and hybrid mesh was not good for simulations.

So here i show results which were obtained with C-mesh generated by blockMesh utility OF, and snappyHexMesh.

blockMesh domain

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mesh near wall

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snappyHexMesh domain

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boundary layer discretization

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Attached Images
File Type: jpg hexasSimple.jpg (44.1 KB, 1374 views)
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about polyDualMesh "Try something smaller than 90"

Posted March 28, 2013 at 02:06 by skeptik (CFD notes)

Originally Posted by lillberg View Post
Try something smaller than 90 deg feature angle since it represents the maximum angle between two neighboring surface normals on a surface without corners. That is, the mesh will consider your surface shape a corner if the angel is larger than this value. I typically use something between 45 and 80 depending on the tet mesh resolution on highly curved surfaces. This might be the root of your problem. Looking at my picture the curved surface in the middle would (wrongly) be treated as a corner if
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note about convergence

Posted March 26, 2013 at 05:39 by skeptik (CFD notes)

Originally Posted by chegdan View Post

There are some strategies that I would try to get these residuals down to something you would like.
  1. Lower your pressure relTol by an order of magnitude compared to U i.e. relTol = 0.001 for P and relTol = 0.01 for U.
  2. Without knowing the mesh you are using you may need to increase the nonorthogonal corrector by 1 or 2. if you are using a tet mesh...then there are many things you can do.
  3. Use first order schemes to start with (you will move to higher order ones
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Forgotten post about airfoilmesh. Domain shape

Posted March 22, 2013 at 05:00 by skeptik (CFD notes)

First time i tried domain like this

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And i got no good results cause pressure distribution shown problems with BC

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I tried to make a circular domain like in this work shown in the next figure

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and only with circular domain i get physically reasonable results.

other figures about mesh i used to

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PISO's last results

Posted March 14, 2013 at 07:39 by skeptik (CFD notes)

SIMPLE showed better results.

May be it was caused by mesh. Tetra mesh with lower y+ shows similar results. Quad+tri 3D extruded mesh did not demonstrate good Cx, Cy.

Name:  kOmega_Piso.jpg
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