WSS calculation

[Kathrin Baumler]

Hi!
I just started using SimVascular 2.0 on a Mac Yosemite, and your documentation for a poiseuille flow problem (http://simvascular.ucsd.edu/docsFlowSolver.html) was very helpful!

I have one question about the WSS output concerning two different outflow conditions. For both settings I specified "zero_pressure_vtp outflow.vtp" in the .cvpre file. I changed the solver.inp file:

Setting 1 applies a resistance condition to the outflow boundary with value 8888 (as proposed in the example)

Setting 2 does not set the resistance value (Number of Resistance Surfaces: 0).

Both settings give the expected results for the pressure and velocity.

The wall shear stress:
In Setting 2 the wall shear stress is as it should be (in this example ~0.1).

For Setting 1 I get the expected wall shear stress on the surface everywhere _except_ on the curve which is the intersection of outflow boundary and cylinder_wall boundary. There the wall shear stress values are very high, about ~200000.

Do you have any idea what might cause this?

Best,
Kathrin

[Hongzhi Lan]

Hi,

Thank you for the interest in using SimVascular 2.0. What specific version are you using? Is it the latest version 2.0.10320? In your simulation, the only difference between the two cases is Setting 1 has resistance at the outflow boundary, right?

Best,
Hongzhi

[Kathrin Baumler]

Hi!

I am using the version 2.0.10222.
I installed this Version beginning of March, and the file
/Applications/SimVascular.app/Contents/Resources/release-date
contains "150222010007";

Yes, the only difference in both runs was the resistance, so in Setting 1, the solver.inp file contains:
Number of Resistance Surfaces: 1
List of Resistance Surfaces: 3
Resistance Values : 8888.0

In setting 2 those three lines are commented.

Thanks,
Kathrin

[Hongzhi Lan]

Hi

Can you give a try to the latest version 2.0.10320? We improved the WSS calculation in this version, which gives better results. In this version you can also calculate wss in the tab under "Create VTU Files" after the simulation.

Thanks,
Hongzhi

[Kathrin Baumler]

Hi!

The new release gives the correct result in both settings!
Thanks!

Best,
Kathrin