Deforming Wall
 

Hi friends,

I am simulating a simple 2D duct with an inlet and outlet.
I have written a UDF using Define_Grid_motion Macro for moving nodes of lower and upper walls. I have defined inlet and outlet as deforming wall(plane type) in Dynamic mesh-->Zones. The problem is that inlet and outlet do not deform with the same speed as adjacent walls. I have attached a picture of my problem after afew time steps.
May you help me to find out where problem lies?
tnx.

Can you please elaborate your problem? Also specify direction of motion and zone condition on figure.

The horizontal walls are moving inward.
Left vertical wall: Inlet
Right vertical wall: Outlet

Type of both vertical walls is"Deforming wall-->plane" which is defined in "Dynamic mesh-->zone..."

The problem is that the nodes at corners do not move with the same speed as others on Horizontal walls. After a few time steps the faces which located at corners of Horizontal walls stretch in and mesh skewness increases which eventually results in negative volume appearance.

Using layering option, you can simulate such problems.
Follow the problem of piston-cylinder.

best wishes