Force by buoyancy

champshof · November 16, 2009, 06:09

Dear all,

The difference in Buoyancy forces switched on or off have a major influence on the forces in my bouyancy direction of my model. For that reason I modelled a simple isothermal, single phase 2D cylinder flow, but still the buoyancy has a major influence. When switched off I get a drag force of -0.33N and when switched on I get a drag force of 0.70N.

Epecially the negative drag force is very weird, anyone an explanation?

champshof · November 17, 2009, 06:09

nobody an idea?

champshof · November 17, 2009, 10:54

found the answer: pressure build op due to the domain (to small)!

ghorrocks · November 17, 2009, 20:00

For future reference: The reason you got no replies is because you did not provide sufficient information about what you were doing and any error messages, convergence histories or anything to debug the problem. We are not mind readers. So I just don't bother answering questions which are poorly asked. I have better things to do.

champshof · November 18, 2009, 03:07

thanks for the tip!

November 16, 2009, 06:09	Force by buoyancy	#1
champshof New Member Join Date: Nov 2009 Posts: 11 Rep Power: 15	Dear all, The difference in Buoyancy forces switched on or off have a major influence on the forces in my bouyancy direction of my model. For that reason I modelled a simple isothermal, single phase 2D cylinder flow, but still the buoyancy has a major influence. When switched off I get a drag force of -0.33N and when switched on I get a drag force of 0.70N. Epecially the negative drag force is very weird, anyone an explanation?

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November 17, 2009, 06:09		#2
champshof New Member Join Date: Nov 2009 Posts: 11 Rep Power: 15	nobody an idea?

November 17, 2009, 10:54		#3
champshof New Member Join Date: Nov 2009 Posts: 11 Rep Power: 15	found the answer: pressure build op due to the domain (to small)!

November 17, 2009, 20:00		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,366 Rep Power: 139	For future reference: The reason you got no replies is because you did not provide sufficient information about what you were doing and any error messages, convergence histories or anything to debug the problem. We are not mind readers. So I just don't bother answering questions which are poorly asked. I have better things to do.

November 18, 2009, 03:07		#5
champshof New Member Join Date: Nov 2009 Posts: 11 Rep Power: 15	thanks for the tip!