Hi everybody,

In FLUENT 6.1 , I tried to compute the compression process. I used the piston -full UDF and the RPM was 100 only. I used incompressible ideal gas law. I found that during compression and subsequent expansion there was rise neither in pressure , nor temperature and also not with density, though the effect of piston on generating a particular velocity field was visible.

How is it possible that in a compression process, all these things are perfectly constant. With incompressible ideal gas law, are we not supposed to get rise in temperature and subsequently density ? I don't want to use ideal gas law as the Mach number is very very small due to the low engine rpm.

Thanking you for your time and patience .

Are you referring Dynamic mesh manual of fluent? I have tried In-cylinder simulation given as an example in this manual. I got the temperature at the end of compression process as per the isentropic law.

Please set up the case file again with due care to all moving boundary conditions.

Best luck!!

In Fluent, it must to set ideal gas to have temperature and density rise. That is my experience.