External aerodynamics of an aircraft: pressure based solver or density based solver?

shereez234 · April 29, 2015, 12:00

Hello guys;

Can any one tell me if it will be okay to use pressure based solver to simulate an external flow past an aircraft at M = 0.85 and Re = 5 million? or is density based solver a must?

Also; When setting reference values such as reference area and length I have put the Sref of the wing as 383 m2 and ref length as the reference chord length 7m? is this the standard way. Please help me and share any views. I have been having trouble with this for a while.

gdbb89 · April 30, 2015, 14:33

Compressible effects need to be accounted for once you exceed M = 0.3. I would highly suggest a density-based solver. Chord length should be your reference length (you are solving for wall shear/drag, yes?), and the planform area should be your reference area (integrating wall shear along this area for total skin friction drag).

shereez234 · April 30, 2015, 16:30

Thanks for the reply. One more question:

What do you think is a reasonable mesh size to get an accurate drag?

Would 5-8 million elements be reasonable?

April 29, 2015, 12:00	External aerodynamics of an aircraft: pressure based solver or density based solver?	#1
shereez234 Senior Member M Sereez Join Date: Jan 2014 Location: England Posts: 353 Blog Entries: 1 Rep Power: 13	Hello guys; Can any one tell me if it will be okay to use pressure based solver to simulate an external flow past an aircraft at M = 0.85 and Re = 5 million? or is density based solver a must? Also; When setting reference values such as reference area and length I have put the Sref of the wing as 383 m2 and ref length as the reference chord length 7m? is this the standard way. Please help me and share any views. I have been having trouble with this for a while.

April 30, 2015, 14:33		#2
gdbb89 New Member Join Date: Apr 2015 Posts: 17 Rep Power: 11	Compressible effects need to be accounted for once you exceed M = 0.3. I would highly suggest a density-based solver. Chord length should be your reference length (you are solving for wall shear/drag, yes?), and the planform area should be your reference area (integrating wall shear along this area for total skin friction drag). shereez234 likes this.

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April 30, 2015, 16:30		#3
shereez234 Senior Member M Sereez Join Date: Jan 2014 Location: England Posts: 353 Blog Entries: 1 Rep Power: 13	Thanks for the reply. One more question: What do you think is a reasonable mesh size to get an accurate drag? Would 5-8 million elements be reasonable?