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-   -   Pulsatile pressure inlet with pressure outlet (http://www.cfd-online.com/Forums/fluent/79026-pulsatile-pressure-inlet-pressure-outlet.html)

a.lynchy August 10, 2010 07:14

Pulsatile pressure inlet with pressure outlet
 
Hi everyone


I am trying to model blood flow in an artery. To do this I want to specify a pulsatile pressure inlet using a UDF and find the resulting pressure at the outlet from the pressure that is dropped through the system.

However when I use a pulsatile pressure inlet with a pressure outlet, I am required to set a value for pressure at the outlet (this outlet pressure I donít want to set, I want to determine this). Fluent takes the pressure value at the outlet as a constant and adjusts the pressure inlet depending on the pressure loss in the system. Therefore I end up with a pulsatile pressure inlet and steady pressure outlet.

I realise this is to do with the way the Fluent solver works but is there any way I can specify the pulsatile pressure inlet I require and have fluent determine the transient pressure outlet ? Is this the best way to go about modelling blood flow when using pressure BCís?

Many Thanks

amoon March 22, 2012 11:41

Quote:

Originally Posted by a.lynchy (Post 270956)
Hi everyone


I am trying to model blood flow in an artery. To do this I want to specify a pulsatile pressure inlet using a UDF and find the resulting pressure at the outlet from the pressure that is dropped through the system.

However when I use a pulsatile pressure inlet with a pressure outlet, I am required to set a value for pressure at the outlet (this outlet pressure I donít want to set, I want to determine this). Fluent takes the pressure value at the outlet as a constant and adjusts the pressure inlet depending on the pressure loss in the system. Therefore I end up with a pulsatile pressure inlet and steady pressure outlet.

I realise this is to do with the way the Fluent solver works but is there any way I can specify the pulsatile pressure inlet I require and have fluent determine the transient pressure outlet ? Is this the best way to go about modelling blood flow when using pressure BCís?

Many Thanks

Dear all,
I am using Ansys to simulate how sinusoidal pressure at the inlet of a tube propagates and arrives to the output.
I am going to record the pressure at both inlet and outlet on the same time.
Please can anyone tell me how i can do that.
many thanks
amoon

doronzo March 22, 2012 12:02

hi

please anybody corrects me if i'm wrong, but what i know is that pressure outlet refers to eventual backflows, and not to the main flow, so the obtained outlet pressures are a simulation result, whereas the input value to the pressure outlet panel is to be referred to the backflows, if there are.

also, introducing a pressure value in the operating conditions panel allows not to introduce any pressure at the outlet

regards

nikhil March 23, 2012 14:45

Do you have the mass flow rate information through the domain?
If you have, then what you can do is treat your outlet as "Mass flow inlet". Provide negative values of mass flow rate at this boundary ( doing so you will drive the flow out of the domain). And you will be able to find the resulting pressure at the outlet boundary


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