Pressure inlet condition

[Sita Drost]

Hello all,

Is it possible in SimVascular to use a pressure waveform instead of a flow rate waveform as an inlet condition? I couldn't find anything on this in the documentation or on the forum.

Thanks in advance for your help,
Sita

[Weiguang Yang]

Technically, you can prescribe a pressure waveform for an inlet using a GenBC boundary condition. The GenBC tutorial shows how to prescribe an RCR BC for an outlet by providing dp/dt=f(Q,R,C,Rd) at each time step. Similarly, you can prescribe a pre-defined pressure waveform by providing dp/dt at any time point t for the inlet. If dp/dt=0, a constant pressure is prescribed. I am providing an example for a constant pressure prescribed at the inlet of a cylinder.
https://www.dropbox.com/s/qqlehpi46fw0j ... ar.gz?dl=0

You can modify it to add a pressure waveform.

Apart from potentially increased computational cost and numerical instability (which might be insignificant), prescribing a pressure waveform doesn't necessarily make the flow satisfy your target values. So you still need extra work to adjust other parameters in order to match target pressures and flow. Just don't forget to check your resulting inflow data when the Nuemann BC (pre-defined pressure or a lumped parameter model defined pressure) is applied to the inlet. Sometimes the flow is not physiological. Generally speaking. I don't recommend doing that.

[Sita Drost]

Thanks a lot for this comprehensive explanation! I'll start with the example you provided and work from there, see if it gets me where I want to go.

[Alexandre Costa]

Hi Weiguang Yang,
Could you share again the cylinder example with the pressure prescribed at inlet ?
Thanks,
Alexandre

[Alexandre Costa]

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