[martn]

Hi everybody!

I'm trying to build up a case of an engine simulation. In the first steps I created a case with the overRhoPimpleDyMFoam solver based on the overPimpleDyMFoam tutorial. I managed to run the simulation of a simple cylinder with a moving piston and closed valves. So this is just a compression of air in a cylinder.

For the overset mesh I defined the whole cells under the upper side of the piston as "hole" (0). Furthermore a small area on top of the piston is defined as overset.
Now I want to compare the result of this simulated compression with the theoretical pressure curve to validate the whole simulation.
I used the function objects (probes) in the controlDict to write out the pressure in a specific point near the TDC. The dimensions of the cylinder are (0.1 0.1 0.1) and the pressure probe location is in (0.05 0.05 0.095). The piston moves in the direction of the z-axis from z=0.01 till z=0.07.

The problem is that the pressure curve is not realistic as you can see on the attached picture. You can just see a small saddle point in the near of BDC and TDC but theoretical there must be the minimum and maximum of pressure.
You can also see an half cut of my quadratic cylinder and my whole case in the attached files.

Has anybody an idea where the problem can be? Or is it just not possible to simulate such a compression with this overset tool of OpenFOAM?

Many thanks in advance!

Best wishes,
Martn