[vaibhavvsr]

I am doing a 3D CFD simulation of an External Combustion Engine on Ansys Fluent 2022. I am facing a problem in sliding mesh/dynamic mesh while previewing the mesh motion.

I have two volumes, both fluid domains, one is "Clearance Volume" which has fixed volume and stationary. The other volume is "Hot Space" which is a variable volume, it is expanding/contracting according to a UDF applied on one face of the volume. Both volumes are adjecent to each other and the fluid has to pass between them along with heat transfer. Fluid is gas, single phase material.
The problem I am facing is that while previewing the mesh motion, the mesh nodes of the "hot space", which are on the side of clearance volume, are not moving; they get fixed while all the other mesh of this hot space moves as should be. Because of these fixed nodes, negative volumes are created, and the mesh fails. I have attached the images for reference.

I figured out that it could be a problem in the mesh interface setting, but after setting the interface as "Periodic Boundary Condition", the same situation arose. I also tried setting the mesh interface as "Periodic Repeats", which should be the right option for setting up the sliding mesh. But an error of "Message from the Cortex Process - Compute processes interrupted. Processing can be resumed." keeps coming up, and I cannot preview the mesh motion.

It's a transient problem the moving mesh option is applied in Cell Zone conditions on the "hot space" volume. I have defined the dynamic mesh zones as follows: The top wall of Hot space as Stationary, the Side walls as deforming and the bottom wall as a rigid body with motion attributes of UDF. I have used the macro DEFINE_CG_MOTION in the UDF. ( I have been refrencing the Ansys Fluent Manual)

I would be grateful if anyone can help me regarding this or guide me in the right direction.