boundry condition

raminostadi · September 29, 2016, 02:57

Hello expert.
I am working on bifurcating artery. I need to compare my resut with article but I have a problem with boundry condition in that article.
in the article just have been writen 2 sentences about boundry condition:

''The flow is forced by setting pressure difference between inlet and outlets

of the vessel systemThe pressure difference used in the CFD simulation to

force the blood flow was set to 40 Pa which resulted in the flow

rate of 4.5 ml/s''

I am not sure about boundry conditions.

which boundry condition should I put in fluent setup for inlet and outlets?

please help me.

pakk · September 29, 2016, 05:10

"'The flow is forced by setting pressure difference between inlet and outlets of the vessel system"
So they put a pressure on the inlet and a pressure on the outlet.

"The pressure difference used in the CFD simulation to force the blood flow was set to 40 Pa"
So the inlet pressure was 40 Pa higher than the outlet pressure.

You are probably doing an incompressible calculation. Set the operating pressure at a typical pressure (101325 Pa for atmospheric pressure, I guess blood is in the same range but I am no expert on that), and set the gauge pressure at the inlet at 40 Pa and at the outlet at 0 Pa. Then you did what the article formulated. The flow of 4.5 m/s is a result of the simulation, so you should use that to check your results and not use that as input.

September 29, 2016, 02:57	boundry condition	#1
raminostadi Member ramin Join Date: Jul 2016 Posts: 41 Rep Power: 9	Hello expert. I am working on bifurcating artery. I need to compare my resut with article but I have a problem with boundry condition in that article. in the article just have been writen 2 sentences about boundry condition: ''The flow is forced by setting pressure difference between inlet and outlets of the vessel systemThe pressure difference used in the CFD simulation to force the blood flow was set to 40 Pa which resulted in the flow rate of 4.5 ml/s'' I am not sure about boundry conditions. which boundry condition should I put in fluent setup for inlet and outlets? please help me.

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September 29, 2016, 05:10		#2
pakk Senior Member Join Date: Nov 2013 Posts: 1,965 Rep Power: 26	"'The flow is forced by setting pressure difference between inlet and outlets of the vessel system" So they put a pressure on the inlet and a pressure on the outlet. "The pressure difference used in the CFD simulation to force the blood flow was set to 40 Pa" So the inlet pressure was 40 Pa higher than the outlet pressure. You are probably doing an incompressible calculation. Set the operating pressure at a typical pressure (101325 Pa for atmospheric pressure, I guess blood is in the same range but I am no expert on that), and set the gauge pressure at the inlet at 40 Pa and at the outlet at 0 Pa. Then you did what the article formulated. The flow of 4.5 m/s is a result of the simulation, so you should use that to check your results and not use that as input.