CFD Online Discussion Forums - [blockMesh] Wedge type mesh: generation OK but the mesh has bug for some cells!

Hello,

I'm working on a case (flow inside a nozzle) where my geometry is axisymmetric and I want to do simulation with only one quarter of it (for cpu time saving).

I create my mesk by generating a .m4 file with Matlab and then create a blockMeshDict file with this .m4 file (I know that can sound complicated, but it works).

The mesh is generating without any problem. But I have a block that gets some bad cells (you can see it on the attached image from paraview) and I don't know why! This block has only 6 vertices because it is on the axis.

I have isolated this particular block in order to understand the bug easier, here is my blockMeshDict:

PHP Code:


		
			
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.2.2                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

 convertToMeters 1.000000e-06;
 
 vertices 
 (
 //front
 (             400               0               0 ) // 0 pt 4 (p4f) 
 (             450               0               0 ) // 1 pt 15 (p15f) 
 (             450 24.7487373415292 -24.7487373415292 ) // 2 pt 54 (p18b) 
 (             400 24.7487373415292 -24.7487373415292 ) // 3 pt 41 (p5b) 
  
 //back
 (             450 24.7487373415292 24.7487373415292 ) // 4 pt 18 (p18f) 
 (             400 24.7487373415292 24.7487373415292 ) // 5 pt 5 (p5f)
 );
 
 blocks 
 (
 hex (0 1 2 3 0 1 4 5) // i 
 ( 20 7 16) 
 simpleGrading (5 1 1) // sens XYZ
 );
 
 edges 
 (
 );
 
 boundary 
 (
  );
 
 mergePatchPairs 
 (
 );

I have attached a simple case with the mesh, it doesn't work of course because I don't have any patch, but you can generate and visualize the mesh.

What am I doing wrong ?? I have other blocks that have the same configuration (6 vertices, on the axis) but they are all good, I don't understand!