| Dr T |
October 24, 2022 13:37 |
overset mesh boundary conditions leading to solution singularity
2 Attachment(s)
I am trying to run a simple test case with overset meshes. I have a flap inside a tube and I prescribe the motion of the flap. When I run the case with moveDynamicMesh, I get the required mesh motion. However, when I run the fluid solver, the solution always crashes within the first time step. It looks like I am doing something obviously wrong with the bc's but i'm not able to narrow it down. The outer tube is similar to a pipe bc with fixed inlet and zero pressure at the outlet. The overset patch has overset bc's and the flap has movingWallVelocity for U bc. Not sure if there is more to creating cellSets and the topoSet operations beyond what I've done. I have attached the sequence of steps through my run script here. Appreciate any pointers.
Code:
#!/bin/bash
cd flap/
touch flap.foam #
blockMesh #creating the block around the flap; also the refinement zone or overset patch
snappyHexMesh -overwrite | tee log.shm_flap #shm to create the wall patch
topoSet #selecting every cell other than the "flap" patch
subsetMesh -overwrite c0 -patch flap #not sure what this does - adding exposed internal cells to patch "flap"
transformPoints -scale '(0.5 0.5 0.5)' #to bring the flap to the centre (optional)
echo "completed meshing to flap part...moving to the background mesh"
cd ..
cd backGround/
touch backGround.foam
blockMesh #background mesh
echo "completed meshing the background part...merging meshes"
mergeMeshes . ../flap -overwrite | tee log.mergeMeshes
topoSet | tee log.topoSet #setting the cell sets c0 and c1
topoSet -dict ./system/topoSetDict_movingZone | tee log.movingZone #creating a zone for dynamicMeshDict reader
rm -rf 0
cp -r 0_org 0
setFields -dict system/setFieldsDict_zoneID | tee log.setFields_zoneID #0 for low priority; 1 for higher priority
transformPoints -scale '(0.001 0.001 0.001)' #scaling the entire mesh to m
checkMesh | tee log.checkMesh
cd ..
echo "completed the pre-processing steps..."
#processing
cd backGround/
#check the mesh movement by uncommenting the below line
#moveDynamicMesh
overPimpleDyMFoam | tee log.solver
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