Porous Domain

ijk · August 30, 2010, 10:32

Hi all,

I am simulating a heat exchanger in CFX. I have data of velocity vs pressure drop. From this data I work out linear and quadratic resistance coefficients.

The drop is in one direction only (the z direction in my model) so I specify a streamwise coefficient multiplier of 100 to block the flow in the other directions. What happens to the momentum in the x and y directions as the flow enters the domain - does it just disappear?

The data for my heat exchanger is based on an inlet flow solely in the z direction but in my CFX model the flow has swirl before it enters. Therefore I need the CFX model to account for extra losses due to the flow approaching the heat exchanger at an angle. Can someone please help?

ghorrocks · August 30, 2010, 20:03

CFX will simply put the resistance coefficients you specify in the cross directions, and this will slow the flow down until it approaches straight. If you want CFX to correctly model the deceleration of the swirl then you need to correctly specify the cross flow resistance coefficients.

August 30, 2010, 10:32	Porous Domain	#1
ijk Member Join Date: Apr 2010 Posts: 33 Rep Power: 16	Hi all, I am simulating a heat exchanger in CFX. I have data of velocity vs pressure drop. From this data I work out linear and quadratic resistance coefficients. The drop is in one direction only (the z direction in my model) so I specify a streamwise coefficient multiplier of 100 to block the flow in the other directions. What happens to the momentum in the x and y directions as the flow enters the domain - does it just disappear? The data for my heat exchanger is based on an inlet flow solely in the z direction but in my CFX model the flow has swirl before it enters. Therefore I need the CFX model to account for extra losses due to the flow approaching the heat exchanger at an angle. Can someone please help?

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August 30, 2010, 20:03		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,858 Rep Power: 144	CFX will simply put the resistance coefficients you specify in the cross directions, and this will slow the flow down until it approaches straight. If you want CFX to correctly model the deceleration of the swirl then you need to correctly specify the cross flow resistance coefficients.