Inlet PT different from BC

cbrian · March 26, 2015, 14:50

Hello,
I'm running CFX analyses of a centrifugal diffuser, with PT/velocity direction inlet and PS exit BC's. The baseline ran with no issues, but two redesign attempts (very similar grid, same boundary conditions) do not seem to be running correctly. The inlet total pressure is varying as much as 10% from the BC, and the mass flow is only a tenth of the baseline. Has anyone experienced anything like this?

ghorrocks · March 26, 2015, 17:50

Sounds like a FAQ: http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F

Unless you have checked the convergence, mesh and time step size is suitable for your simulation then you have no idea if your results are accurate or not.

March 26, 2015, 14:50	Inlet PT different from BC	#1
cbrian New Member Brian Join Date: Feb 2015 Posts: 15 Rep Power: 11	Hello, I'm running CFX analyses of a centrifugal diffuser, with PT/velocity direction inlet and PS exit BC's. The baseline ran with no issues, but two redesign attempts (very similar grid, same boundary conditions) do not seem to be running correctly. The inlet total pressure is varying as much as 10% from the BC, and the mass flow is only a tenth of the baseline. Has anyone experienced anything like this?

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March 26, 2015, 17:50		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,872 Rep Power: 144	Sounds like a FAQ: http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F Unless you have checked the convergence, mesh and time step size is suitable for your simulation then you have no idea if your results are accurate or not.