Muffler flow analysis
 

Hi all

I did a preliminary Muffler CFD using both star-cd and cfx. I modelled the exhaust pipes, muffler(perforated, reactive type) and the tailpipe to considerable detail

I assumed Steady state, incompressible, turbulent flow scenario of homogeneous fluid(air ideal gas instead of exhaust gas). heat transfer was ignored

At inlet(after sufficient distance from the turbo), velocity/mass flow rates are known

preliminary analysis revealed that velocity at tailpipe equal to that of the inlet.(which may not be realistic)

I want to know how to define the BCs, what are all to define so that my simulation is realistic?

please let me know whether 1) my assumption of steady state is valid? 2) my assumption of incompressible is valid? 3) the order of magnitude of temperature and velocity of exhaust gases when issuing out of tailpipe..for a typical 6 cyl diesel engine

thanks and regards srivatsan