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proper Boundary Conditions-coronary artery

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Old   May 2, 2012, 07:44
Default proper Boundary Conditions-coronary artery
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Dear all,

I want to simulate the flow of a contrast agent bolus in blood through a coronary artery with several bifurcations and we were dicussing in our group about the proper boundary conditions in this case. We used to use a velocity inlet and an outflow condition depending on how the flow is split at the bifurcations. But now we considered using a pressure inlet and maybe a pressure outlet as well and have no idea what would be the correctest solution. If we use a typical pressure value at the inlet, how can we get a good approximation for the pressure values at the outlets? Does anbody has experience with this problem?
Thank you for all your help an ideas!
Lilly
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Old   May 2, 2012, 08:25
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Originally Posted by Lilly View Post
Dear all,

I want to simulate the flow of a contrast agent bolus in blood through a coronary artery with several bifurcations and we were dicussing in our group about the proper boundary conditions in this case. We used to use a velocity inlet and an outflow condition depending on how the flow is split at the bifurcations. But now we considered using a pressure inlet and maybe a pressure outlet as well and have no idea what would be the correctest solution. If we use a typical pressure value at the inlet, how can we get a good approximation for the pressure values at the outlets? Does anbody has experience with this problem?
Thank you for all your help an ideas!
Lilly

but are you considering a rigid artery?
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Old   May 2, 2012, 08:43
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yes, at first I want to consider a rigid artery-wall
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Old   May 2, 2012, 08:49
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I think you need to prescribe the mass flow rate to avoid spurious solutions in the artery bifurcation...
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Old   May 2, 2012, 09:10
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Thank you for your help FMDenaro!

But I am afraid I cannot use a pressure inlet and the flow rates at the bifurcation at FLUENT simultaneous (I get a warning if I do so).
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Old   May 3, 2012, 01:42
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Quote:
Originally Posted by Lilly View Post
Dear all,

I want to simulate the flow of a contrast agent bolus in blood through a coronary artery with several bifurcations and we were dicussing in our group about the proper boundary conditions in this case. We used to use a velocity inlet and an outflow condition depending on how the flow is split at the bifurcations. But now we considered using a pressure inlet and maybe a pressure outlet as well and have no idea what would be the correctest solution. If we use a typical pressure value at the inlet, how can we get a good approximation for the pressure values at the outlets? Does anbody has experience with this problem?
Thank you for all your help an ideas!
Lilly
If you are using CFX you use flow rate at the inlet and outlets are just outflow
If you are using Fluent calculate velocity from flow rate, use outflow at the outlet
I have two papers published in the field of artificial heart pump
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Old   May 3, 2012, 09:14
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Thank you cfd_user!

Do you mean I should calculate the velocity corresponding to flowrate=area*velocity for the inlet?
I am not sure whether I am allowed to use "outflow" as boundary condition since I have a mixture-model (blood and contrast agent)?
And is there any reason why you didn't use the pressure as outlet and/or inlet boundary condition?

It would be really nice, if you could give me some information!
Thank you!
Lilly
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