| kaszt |
April 1, 2016 21:18 |
Problem with using createPatchDict to define cyclic boundaries
1 Attachment(s)
Hello,
I'm having some problems with periodic boundary conditions for a mesh I created with Cubit to solve for laminar flow over a cylinder. I defined the top and bottom boundaries within Cubit as "periodic", but OpenFOAM doesn't recognize Cubit's definition of periodic boundaries (i.e. they were written as type "wall" in my boundary file after running fluentMeshToFoam). To solve this problem, I tried two things: first, I modified my boundary file as follows:
Code:
FoamFile
{
version 2.0;
format ascii;
class polyBoundaryMesh;
location "constant/polyMesh";
object boundary;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
//5
6
(
//wall_4 // top and bottom; want to make this into 2 patches of type "cyclic"
//{
//type wall;
//inGroups 1(wall);
//nFaces 400;
//startFace 812000;
//}
// Patches for top and bottom...
top // top boundary
{
type patch;
nFaces 200;
startFace 812000;
}
bottom // bottom boundary
{
type patch;
nFaces 200;
startFace 812200;
}
velocity-inlet_5
{
type patch;
nFaces 200;
startFace 812400;
}
outflow_6
{
type patch;
nFaces 200;
startFace 812600;
}
wall_7 // cylinder walls
{
type wall;
inGroups 1(wall);
nFaces 800;
startFace 812800;
}
frontAndBackPlanes
{
type empty;
inGroups 1(empty);
nFaces 812800;
startFace 813600;
}
)
Then I used a createPatchDict file to create the cyclic patches; below is how I defined my file:
Code:
// Sync coupled points
pointSync true;
// Create patches
patches
(
{
// Name of new patch
name periodic_top;
// Dictionary to construct new patch from
patchInfo
{
type cyclic;
neighbourPatch periodic_bottom;
matchTolerance 0.01;
// optional; set transformation tensor
transform translational;
separationVector (0 50 0); // distance between two patches in "y"
}
// How to construct; either patches or set
constructFrom patches;
// If constructFrom = patches : name of patches
patches (top);
// If constructFrom = set : name of faceSet
set f0;
}
{
// Name of new patch
name periodic_bottom;
// Dictionary to construct new patch from
patchInfo
{
type cyclic;
neighbourPatch periodic_top;
matchTolerance 0.01;
// optional; set transformation tensor
transform translational;
separationVector (0 -50 0);
}
// How to construct; either patches or set
constructFrom patches;
// If constructFrom = patches : name of patches
patches (bottom);
// If constructFrom = set : name of faceSet
set f0;
}
);
However, when I try to run
Code:
foamJob createPatch -overwrite
I get the following error:
Code:
--> FOAM FATAL ERROR:
face 61 area does not match neighbour by 2.76759620807% -- possible face ordering problem.
I have attached a picture of the mesh I am trying to work with; the periodic boundary conditions would be for the top and bottom boundaries, therefore I set the separationVector to be the distance between the boundaries in "y" (since I am using symmetry in the x-axis). I am pretty stuck with this problem, and I'm not sure if I am using the createPatchDict correctly. If anyone has any advice or tips as to what I am doing incorrectly, I would appreciate your help very much. Thank you in advance for your time!
Attachment 46424 |
