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-   -   How to start unsteady propeller CFD (http://www.cfd-online.com/Forums/main/16310-how-start-unsteady-propeller-cfd.html)

Joe February 4, 2009 11:44

How to start unsteady propeller CFD
 
Hi,

I have to do an unsteady CFD on an airplane propeller in front of a non-symmetric fuselage (sliding mesh).

Does anyone know, with what kind of steady solution I should start the computation? The problem is unsteady by definition, so there is no real steady solution to start with, is there? How should such an unsteady computation be started without having to accelerate all the way from zero velocity?

Thanks,

Joe

Flynt February 14, 2009 02:13

Re: How to start unsteady propeller CFD
 
Starting from a steady solution might appear faster but may not give the correct result. In rotorcraft unsteady simulation almost always start from nothing and require >3 full revolutions to get the transients far enough away from the blades to not be important. If you start from a steady state solution the flow field still has start up transients (just different ones) that take >3 revs to move away so you might as well start from nothing. As a side note: If your looking at loads on the fuselage it might take substantually more revs than 3.

Bryan


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