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Hi all,

When I'm applying a steady parabolic flow on the inlet, I see that for some reason in the calculation of this profile not only a velocity in the required direction is present, but there is also a small parabolic velocity profile in the other two directions (It is in the order of 10^-4 of the velocity in the normal direction). Anybody has an idea why this is? For fully developed flow the velocities in the other directions should ofcourse be zero.

Thanks in advance!

The inlet profile prescribed by bct.dat file should give zero velocity in the non-axial direction. In the domain, probably you won't get 0.0 exactly. 1e-4 doesn't seem too bad. If you want to further reduce it, you can consider extending the pipe. L~10D may not be sufficient.

Hi,

Thanks for your reply. I've checked the bct.dat file and the prescribed velocities in the non-axial direction are not exactly zero. I've attached the file here: https://we.tl/t-zVyxgqr3Oq
Any idea what causes this?

I found the problem. For some reason, if I apply inflation layers in my mesh, the mapping of the velocity profile on the inlet boundary introduces non-axial velocity components (approx. 10^3 times smaller than the velocity in the axial direction). When I'm not using inflation layers in my mesh, this non-axial velocities are approx. 0 (in the order of 10^-12 to 10^-20, but still not completely 0). This is for both parabolic and womersley velocity profiles (I didn't check plug). Is this a bug in the creation of the bct.dat file?

Hi Dylan,

I think that the velocity profile mapping should be the same wether you are using boundary layers or not.

Please file a bug for this on GitHub (https://github.com/SimVascular/SimVascular/issues) and I'll have a look. Be sure to include any data files (mesh, bct.dat, etc) for both cases.

Thanks,
Dave

Hi David,

Thanks for your reply, I've filed the bug on the GitHub.

Thanks in advance for the help,

Dylan