How are the flow files obtained in the clinical examples?

[Justin Tso]

Hi, I was wondering how the flow files for the inlet boundary conditions were obtained in your clinical examples (or the general standard for obtaining these flow files)? In addition, in your coronary normal clinical example, I see that the flow and pressure were graphed against time after the simulation was performed. The user guide doesn't go into how to create these graphs? Is it through Paraview, as I don't see a way to access the raw data produced by the simulation to create these graphs?

[Weiguang Yang]

The inlet flow such as Figure 8: Aortic inflow waveform is usually obtained by PCMRI (phase contrast) that gives you flow rate vs time for a imaging plane. If you don't have your own measurements, you can obtain the inflow waveform data from some MRI studies. To plot pressure/flow vs time, you can use matlab or python or excel. Simvascular postsolver generates txt files for pressure/flow on each outlet/inlet based on the vtu/vtp files converted from restart.x files. (https://simvascular.github.io/docsFlowS ... ostprocess). Then, you can load them into matlab to get a plot shown in the example.

[Justin Tso]

Hi, thank you for your help. I have access to PCMRI data, but how exactly do you convert this data into a .flow file? Alternatively, if I wanted to make a simple constant flow file like the one in the User Guide, how do I create this .flow file? Looking it up online, the only thing I've seen that can open or create .flow files is Expression Sketchflow. Is this the program being used, or is it something else? Thank you!

[Weiguang Yang]

You can use some software to process the PCMRI data (usually in Dicom format) to obtain volumetric flow rate vs time. For example, http://medviso.com/segment/

Once you have time vs flow rate, you can copy and paste them into a text editor (e.g. vim or gedit) and save them as .flow file. Similarly, for constant inflow, just put two lines of data into the .flow file.

[Nishanth Surianarayanan]

Hi Developers,

I see the all_results-flow file and I find some values to be negative. Is it the same convention as the inflow file, where we assume that negative means flow inside the model and positive means flow out of the model?

Please explain!

Thank you,
Nishanth