Ideal Gas compression Analysis using acusolve

Hi Good Day!

I ran an ideal gas compression analysis for our piston-cylinder model. I considered only the BDC-to-TDC mesh motion (upward stroke) and adjusted the time vs. displacement curve accordingly. Boundary conditions were applied properly.

The simulation ran without errors and showed results, but the pressure peaked mid-stroke and dropped at TDC — which is unexpected. Ideally, pressure should be highest at TDC.

To verify, I used the same setup from the ideal gas compression tutorial and modified it to include only the upward stroke. The result was the same — pressure dropped at TDC.

Could you help me understand why this is happening?