What are boundary TETs and how to clean them?

What are boundary TETs?

1. Boundary tet refers to an element that has all the nodes on the surface of the model. In flow analysis, these elements are also termed as dead elements.
2. Usually, imposed velocity on contact wall is equal to zero, hence if a given tetra element has all 4 nodes all the wall then it will not move and this may cause oscillation/hot spots in simulation.

3. This specific element will then have zero material flow everywhere and hence it is classify as a dead element. This is illustrated in the below figure.

How to avoid?

1. The correct way to address it is to use CFD tet mesh.
2. For regular tetra mesh
   1. Find all elements which has all 4 nodes on wall.
   2. Split element by inserting a node at center of the element. This will split the element into 4 elements.
   3. SimLab has this feature in Quality tab.