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gdtk-uq / gdtk

The Gas Dynamics Toolkit (GDTk) is a set of software tools for simulating high speed fluid flow, maintained at The University of Queensland and the University of Southern Queensland, Australia.
https://gdtk.uqcloud.net/
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Boundary layer velocity #68

Closed jr144393 closed 1 month ago

jr144393 commented 1 month ago

I have noticed some discrepancies with the velocity profile here, for the NoSlip wall condition, WallBC_NoSlip_FixedT, the velocity at the wall seems far from zero.

This is the paraview result:

question1

And the settings for that wall:

question2

question3

Any comments on why this might be so far off? The resolution is not to the proper settings, but wouldn't the velocity at the same resolution still have the velocity at the wall set to zero?

jr144393 commented 1 month ago

Also, I suppose its important to mention this setting is on:

question4

pajacobs-ghub commented 1 month ago

What you show in the first image is the average velocity for the cell, so no the wall velocity. What is your free-stream velocity?

uqngibbo commented 1 month ago

Hi jr,

As PJ said, we don't expect the first cell to actually be zero, since the no-slip condition is applied at the actual interface representing the wall. That said, 541 m/s is a pretty large number.

Tightening the grid clustering to the wall should reduce this number to something more reasonable. You may want to try using the Geometric Cluster function: https://gdtk.uqcloud.net/docs/eilmer/eilmer-reference-manual/#_geometric_function