I'm an EE trying to learn the basics of fluid dynamics and CFD, due to my interest in car racing. Currently I'm looking at the flow through exhaust systems to get a feel for what allows the most airflow and therefore the most horsepower. I set up the problem by forcing a boundary condition at the inlet of a certain speed. My question is how to interpret the results to determine what configuration flows the most. Do I want to look for the lowest peak pressure, or the smallest pressure differential from inlet to outlet, or something else? I orginally though it would be the lowest peak pressure, but looking at the results I'm not 100% sure of that now. Some details: I know exhaust is really pulses, but to keep things simple I'm assuming steady-state flow. I've calculated the average exhaust speed based on an assumed horsepower number and the cross sectional area of the exhaust. It gives me a Mach number of 0.06, so I'm assuming incompressible flow. I've estimated Re at 30,000 so I'm treating the flow as turbulent. Thanks, Tom S.