How to set up a sliding mesh?

Daniel Rakhimov

I am solving a test problem on a moving mesh.

As an example, I consider a problem similar to the problem of train moving through tunnel, described in "HW2022.0 - Release Highlights: HyperWorks CFD". (https://www.youtube.com/watch?v=tnUCJ4mOAfs&list=PLGNemB0NFb0BpCdoafrR6_tujpMxoOfSq&index=15) 

It has two solid bodies (fixed and moving {spatial motion}). For the inner surface of a moving body (train), the displacement of the surface is set. An interface surface is defined between the bodies.

The problem is that the mesh between these bodies does not slide relative to each other, but deforms, which leads to the "Severe distortion in specified mesh" error. Setting the interface surface as a sliding surface doesn't help.

I attach the calculation model below. (The mesh has been removed) 

Please tell me how to solve this problem. What model settings were entered incorrectly?

acupro

This would probably involve some 'manual' effort (both manipulating the mesh files and manual editing the input file) to get to work as you intend with the Nodal BC scaling the mesh motion.

If you want to run directly from the GUI:

Use the Arbitrary motion type instead of Specified

Create a translation mesh motion, of any direction, use 0 as the mesh velocity, and apply it to the fixed/outer volume.  (With the inner volume having a different mesh motion applied - in this case no mesh motion applied - the surface between them will be split.)

Apply your desired mesh motion only to the surface of the moving body.

Remove the Advanced Spatial nodal BC.

This should at least allow you to proceed.  Make sure the wall-velocity-type on the ground is zero instead of match-mesh-velocity.  Even though the mesh is moving, the ground velocity should be zero (assuming that's your intent - not to have a moving ground).