[dancfd]

Hello all,

I am having trouble running the case /simpleFoam/airfoil2D when I replace the default mesh with mine, a NACA 0012 in a C-grid (blockMeshDict attached). The problem is that the results show pressure/velocity fluctuations in the far field, and no characteristic pressure field around the airfoil. I thought this might be due to the mesh, since blockMesh gives me the following warnings:

Creating block mesh topology
--> FOAM Warning : 
    From function cellModel::mag(const labelList&, const pointField&)
    in file meshes/meshShapes/cellModel/cellModel.C at line 128
    zero or negative pyramid volume: -0.000497689 for face 0
--> FOAM Warning : 
    From function cellModel::mag(const labelList&, const pointField&)
    in file meshes/meshShapes/cellModel/cellModel.C at line 128
    zero or negative pyramid volume: -1.26062e-08 for face 2
--> FOAM Warning : 
    From function cellModel::mag(const labelList&, const pointField&)
    in file meshes/meshShapes/cellModel/cellModel.C at line 128
    zero or negative pyramid volume: -1.26063e-08 for face 3
--> FOAM Warning : 
    From function cellModel::mag(const labelList&, const pointField&)
    in file meshes/meshShapes/cellModel/cellModel.C at line 128
    zero or negative pyramid volume: -1.26063e-08 for face 4
--> FOAM Warning : 
    From function cellModel::mag(const labelList&, const pointField&)
    in file meshes/meshShapes/cellModel/cellModel.C at line 128
    zero or negative pyramid volume: -1.26063e-08 for face 5
--> FOAM Warning : 
    From function blockMesh::createTopology(IOdictionary&)
    in file createTopology.C at line 397
    negative volume block : 0, probably defined inside-out

I tried to resolve the issue by changing the order of the vertex numbering in block 0 from hex (2 4 6 0 3 5 7 1) to hex (3 5 7 1 2 4 6 0), and that yielded only the following:

Creating block mesh topology
--> FOAM Warning : 
    From function cellModel::mag(const labelList&, const pointField&)
    in file meshes/meshShapes/cellModel/cellModel.C at line 128
    zero or negative pyramid volume: -0.000497664 for face 1

The problem is that now simpleFoam will not even run! (log attached) I am not surprised, because the interface between two of the blocks clearly looks inside out. CheckMesh was not kind either (see checkMeshAdjusted). However, checkMesh had no problem with the first mesh (log.checkMesh).

In a nutshell, the problem is this: blockMesh gives me several warnings when building my mesh that runs; blockMesh only gives one error (which I do not know how to fix) when building the mesh that will not run. CheckMesh gives a worse report to the mesh that blockMesh liked best, and simpleFoam will not run the mesh checkMesh does not like, but will run the other one with poor results.

Can anyone tell me what is wrong with this mesh? I would appreciate any advice.

Thank you,

Dan