[snappyHexMesh] Snappy Hex Mesh - Meshing Problem

Muhammad Asim Sarwar · May 14, 2019, 03:43

Hi all. It is my first thread and I am sorry if I am unable to convey my information properly.

I am new to openfoam and I have started a simulation with heat transfer (chtMultiRegionFoam). My domain is very simple. I have thin rectangular rods with 10mm thickness. The fluid flows inside it.

I am meshing the domain with snappy hex mesh. The problem is that the elements on some fluid domain are perfectly aligned but on some they are distorted (first pic). However, the outer surface of solid domain is perfectly aligned.

The dimension of rod is 200*120mm. On one thread I have read that aspect ratio needs to be close at 1 for snappy hex mesh to work properly. So that's why I have used grading in z direction at both ends so that cell size in x, y and z axis will be same.

fluid.JPG

solid.JPG

blockMesh Dict.txt

SnappyHexMesh Dict.txt

mwaqas · August 23, 2019, 07:23

Hello Muhammad,

SHM is really tricky and sensitive especially multi-region meshing. Even a small change in one parameter has big influence on meshing.

Normally, this problem occurs when you have different refinement on both sides of interface. Try to have same cell size (refinement) across the interface and then after splitting the regions, you will not get distorted mesh.

Regards.

May 14, 2019, 03:43	Snappy Hex Mesh - Meshing Problem	#1
Muhammad Asim Sarwar New Member Join Date: Nov 2018 Posts: 8 Rep Power: 7	Hi all. It is my first thread and I am sorry if I am unable to convey my information properly. I am new to openfoam and I have started a simulation with heat transfer (chtMultiRegionFoam). My domain is very simple. I have thin rectangular rods with 10mm thickness. The fluid flows inside it. I am meshing the domain with snappy hex mesh. The problem is that the elements on some fluid domain are perfectly aligned but on some they are distorted (first pic). However, the outer surface of solid domain is perfectly aligned. The dimension of rod is 200*120mm. On one thread I have read that aspect ratio needs to be close at 1 for snappy hex mesh to work properly. So that's why I have used grading in z direction at both ends so that cell size in x, y and z axis will be same. fluid.JPG solid.JPG blockMesh Dict.txt SnappyHexMesh Dict.txt

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August 23, 2019, 07:23		#2
mwaqas Senior Member Muhammad Waqas Join Date: Jul 2014 Location: Germany Posts: 122 Rep Power: 11	Hello Muhammad, SHM is really tricky and sensitive especially multi-region meshing. Even a small change in one parameter has big influence on meshing. Normally, this problem occurs when you have different refinement on both sides of interface. Try to have same cell size (refinement) across the interface and then after splitting the regions, you will not get distorted mesh. Regards.