Definition of vtp/vtu result variables

[Shannen Kizilski]

I was wondering if there is documentation for the meaning of the various quantities available for visualization in the vtp and vtu results files? Some of them like "pressure" and "velocity" are self-explanatory, but I'm less sure about things like "timeDeriv" and "vinplane_traction".

I believe that the "v" versus "r" at the beginning of some variables refer to whether they were calculated using velocity-based or residual-based methods, but what are the implications of this distinction? For example, should vinplane_traction and rinplane_traction have the same values? Is there information that can be gained by looking at the differences between these?

Thanks in advance!

- Shannen

[Weiguang Yang]

I think timeDeriv is the acceleration, dv/dt and the vinplane_traction is the traction vector of viscous stress tensor, \tau=\mju(\nabla vec{u}+(\nabla vec{u})^T)vec{u}.

Risidual based and velocity based tractions differ. The residual based traction utilizes the wall traction term in the CMM variational form ( in which the no slip BC on the wall is replaced by a Neumann BC) to compute in plane traction and WSS. You can find more details in section 3.6 in Figueroa's thesis.

[Shannen Kizilski]

Thanks for the reply, I'll check out Figueroa's work for more clarity on velocity- versus residual-based calculations.

I'm also interested in the meaning of the time-averaged/integrated variables that are available in the VTP file.
What are the differences among "vTAWSS", "vTAWSS_wss", "vshear_pulse", and "vshear_pulse_wss"?
And "vOSI" versus "vOSI_wss"?

Also for these time-integrated values, do they always incorporate data starting at time=0, or will they only include data included in the "convert results" steps selected?
Example: If I run a simulation for 1000 timesteps with an increment of 0.01 (so a 10 second run), can I convert just the final 4 seconds of the run and have TAWSS and OSI consider only that data? Or will it still calculate using the data starting at t=0? Do I also have to worry about the time increment used in results conversion when looking at TAWSS? If I only convert every 20 timesteps, will my TAWSS results be less accurate because some of the max/min values might be missed in the integration/averaging?

I hope these questions make sense. Thanks!