SnappyHexMesh not conforming the meshing geometry

Oskar PS · July 10, 2025, 11:55

I am currently running a setup where i mix blockmesh blocks and snappyHexMesh blocks in openFoam. The mesh consists of a circular straight pipe made with blockmesh and a T-Junction made in a CAD program and implemented with SHM at the pipe outlet.

When meshing this part SHM does not conform to the correct geometry. At the edge between the pipe outlet and junction inlet SHM does not follow the correct geometry creating an indent in the geometry as pictured.

This phenomena is present at both the inlet part and the outlet parts as pictured.

Currently this junction is being placed at an overlap with the inlet pipe as pictured, when it is not meshed on top of each other but with just a bounding box around the STL the edges are not properly captured. I hope someone is familiar with the problem and has a solution i have multiple pictures and the SHMD file below.

https://drive.google.com/drive/folde...JD?usp=sharing

AtoHM · July 11, 2025, 08:38

As the same happens at the other sides, i strongly recommend using edge refinement to capture the cylinder edges sharply. Use the surfaceFeatures / surfaceFeatureExtract utilities (depending on which OpenFOAM release you work with).

July 10, 2025, 11:55	SnappyHexMesh not conforming the meshing geometry	#1
Oskar PS New Member Oskar P. Sagatun Join Date: Sep 2024 Location: Norway Posts: 10 Rep Power: 3	I am currently running a setup where i mix blockmesh blocks and snappyHexMesh blocks in openFoam. The mesh consists of a circular straight pipe made with blockmesh and a T-Junction made in a CAD program and implemented with SHM at the pipe outlet. When meshing this part SHM does not conform to the correct geometry. At the edge between the pipe outlet and junction inlet SHM does not follow the correct geometry creating an indent in the geometry as pictured. This phenomena is present at both the inlet part and the outlet parts as pictured. Currently this junction is being placed at an overlap with the inlet pipe as pictured, when it is not meshed on top of each other but with just a bounding box around the STL the edges are not properly captured. I hope someone is familiar with the problem and has a solution i have multiple pictures and the SHMD file below. https://drive.google.com/drive/folde...JD?usp=sharing

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July 11, 2025, 08:38		#2
AtoHM Senior Member M Join Date: Dec 2017 Posts: 727 Rep Power: 14	As the same happens at the other sides, i strongly recommend using edge refinement to capture the cylinder edges sharply. Use the surfaceFeatures / surfaceFeatureExtract utilities (depending on which OpenFOAM release you work with).