Multiple Inlets and Reverse Flow

[Joseph Muskat]

Hello,

I'm trying to run a simulation that has 3 inlets and 5 outlets in a simple Circle of Willis.

I'm finding an issue with the solved pressure and velocities; it appears that SimVascular is regarding one of the carotid inlets to be an outlet.

C1.JPG (199.65 KiB) Viewed 725 times

C2.JPG (207.87 KiB) Viewed 725 times

I've scaled the velocity in the lower image to show all the "negative" flow equal to zero--just made it easier to see what I mean. I've run simulations with all the inlets being flipped to normal or not flipped while also running with the Inlet BC flow files having negative and positive values. I continue to see the issue arise. When I swapped the left carotid (negative) to be flipped normal, the simulation solved the right carotid (shown positive) to become the negative one while making the left carotid positive.

Shown above, the basilar artery inlet might have also been considered as an outlet***. I've tried making certain outlets have extremely low resistance in an attempt to pull flow out of the model, but I still saw these problems.

Any advice/tips on reviewing the simulation would be appreciated!

Joseph

Edit: ***

[Adam Updegrove]

Hi Joseph,

How are you setting the multiple inlets in your simulation? Have you run a simulation with multiple inlets before?

Also, have you checked you bct.vtp files? Do the inflow vectors point the correct direction. This is always a good thing to check when you see flow going the opposite direction of what you expect?

Thanks!

SimVascular Development Team

[Joseph Muskat]

Hi Adam,

To setup multiple inlets, I am assigning velocity profiles/inflows to each of my 3 desired locations. For the outlets, I am assigning resistance values. I haven't run with multiple inlets before, but I've worked with single inflow simulations in SimVascular already.

For the bct.vtp files, how would you recommend checking the profiles? I'm currently using the exported .vtu files with Stream-tracers in Paraview to determine which way velocity is traveling.

Thank you,

Joseph

[Joseph Muskat]

As an update, Adam: I'm now viewing the bct.vtp files before running any simulations. I've tried to "flip normal" and add (-) signs to the flow file.

I continue to see a negative velocity profile created for the basilar artery.

[Hongzhi Lan]

Hi Joseph,

Please make sure install the latest version (2017-04-09) including SimVascular and svSolver. the issue for the inlet flow direction has beed fixed. Make sure in your flow rate file, negative values means inward flow.

As Adam, it's always good to double check the direction visually, but load bct.vtp and mesh-complete/mesh-complete.exterior.vtp into Paraview to check the flow direction. If you still have issue, let us know. And you can send me the project.

SimVascular Development Team

[Joseph Muskat]

Hello both,

I ended up getting the simulations to run through random combinations and looking at the bct.vtp files. That tip was very helpful.

I'll install the latest version, but I'm all finished up with this project for now. Thank you for the advice!

Joseph