CFD Online Discussion Forums - mesh missing after snap step

Hello,everybody,

I have got stuck in the snappyHexMesh for a long time, the problem is as follows.

I am trying to simulate a vertical axis wind turbine using AMI in OpenFOAM. The picture below explicitly show the half domain in the vertical direction together with the foil and the AMI setup.
Attachment 64328
and the AMI part (blue) composes of actually the surfaces of a hollow cylindrical stuff, as can be seen:
Attachment 64329

After setting up the geometry, the castellatedMesh step began, and everything looks fine, I can get the mesh between the AMI surfaces, like this:
Attachment 64331

Then I tried snappyHex Step, but after complicated manipulation, the result turns out that there are mesh missing inside the AMI zone, around the place where coarse mesh meets the fine mesh as shown in below:
Attachment 64330

I have tried a lot to solve this problem by changing the parameters in the snappyHexMeshDict concerning the snap step and castellatedMesh step, but I couldn't work it out.

Could someone have some comments and suggestions on this problem? it will be greatly appreciated for that. I have attached the snappyHexMeshDict in this thread, so you can have a look at it. Any comments are quite valuable for me.

Thanks in advance!

Allen

BTW： when the snappyHexMesh goes into the snappyStep, there are a lager lot of warnings, like:

Code:

--> FOAM Warning : 

    From function void Foam::snappySnapDriver::calcNearestFace(Foam::label, const indirectPrimitivePatch&, const scalarField&, Foam::vectorField&, Foam::vectorField&, Foam::labelList&, Foam::vectorField&) const

    in file snappyHexMeshDriver/snappySnapDriverFeature.C at line 333

    Did not find surface near face centre (0.171302 0.138639 -0.0705999)

Does that have something to do with the "missing mesh" reported above? how can I get rid of these?

Attachment 64332