[brightfame3]

Good afternoon.

I am simulating an Internal Combustion Engine in Fluent and I have had some difficulties obtaining any kind of results.

Initially, all valves are closed and their respective cell zones deactivated. The simulation goes well untill one of the valves opens. Here fluent prompts "Divergence AMG...". I tried changing the URF's, improved my mesh and geometry (removing any sharp edges), used coupled and segregated and nothing. I am begining to believe that the problem are my boundary conditions, in particular defining the operating pressure. I am using the ideal gas for density and I have read that when using the ideal gas, it is advised to use 0Pa for operating pressure. However in an IC engine, there will be both regimes (M>0.1 - at the valves & M<0.1 - in the rest of the domain). My doubt is: how should I define my operating pressure?

PS: I have tried with 0Pa and 101325Pa for OP, and the first one went further in the simulation however crashed as well.

Thank you very much in advance!