How best to set up a steady RANS problem that "should" be URANS?

LiveandLetDrive · April 16, 2009, 13:30

My group is simulating the airflow around an open-wheeled racing car and I am specifically focused on the wheels. This is a highly separated flow, especially behind the wheels. Due to computational limitations, most or all of our development will have to be done as steady simulations rather than using URANS with time steps. Is there anything that can be done to optimize the steady simulation (mesh, solutions settings, or otherwise?) to better approximate the appropriate URANS solution?

Thanks, any ideas appreciated.

vishyaroon · April 17, 2009, 16:12

It depends on what parameters you are looking at. If you are just interested in characteristics like flow, pressure etc then a steady state computation is good enough.

however if you want to look at noise or other turbulence related characteristics then you should go for an unsteady simulation.

LiveandLetDrive · April 17, 2009, 20:33

Primarily it is a problem of not being able to get good convergence using the steady assumption. Yes I am just needing flow and pressure (lift/drag) but I don't believe the numbers at this point and previous studies have shown unsteady simulation to be far superior. Without using unsteady is there anything I can do to optimize/make the best of a steady simulation?

April 16, 2009, 13:30	How best to set up a steady RANS problem that "should" be URANS?	#1
LiveandLetDrive New Member CSN Join Date: Apr 2009 Posts: 10 Rep Power: 17	My group is simulating the airflow around an open-wheeled racing car and I am specifically focused on the wheels. This is a highly separated flow, especially behind the wheels. Due to computational limitations, most or all of our development will have to be done as steady simulations rather than using URANS with time steps. Is there anything that can be done to optimize the steady simulation (mesh, solutions settings, or otherwise?) to better approximate the appropriate URANS solution? Thanks, any ideas appreciated.

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April 17, 2009, 16:12		#2
vishyaroon Senior Member Aroon Join Date: Apr 2009 Location: Racine WI Posts: 148 Rep Power: 17	It depends on what parameters you are looking at. If you are just interested in characteristics like flow, pressure etc then a steady state computation is good enough. however if you want to look at noise or other turbulence related characteristics then you should go for an unsteady simulation.

April 17, 2009, 20:33		#3
LiveandLetDrive New Member CSN Join Date: Apr 2009 Posts: 10 Rep Power: 17	Primarily it is a problem of not being able to get good convergence using the steady assumption. Yes I am just needing flow and pressure (lift/drag) but I don't believe the numbers at this point and previous studies have shown unsteady simulation to be far superior. Without using unsteady is there anything I can do to optimize/make the best of a steady simulation?