XFLR5 vs CFD

Using SimScale
101

Thanks Jousef but darn, I thought we were resolving the viscous boundary layer by layering the mesh. How do I directly resolve the viscous sublayer so I can see the separation?

102

I finally figured how write control got changed to 1s and then why it just hung around :bulb::bulb:

When I was playing around with making 1s simulations trying to see yPlus ranges I must have HAD to do it, just so I could get the sim to run.

And actually it was even worse than that, I did not realize that the >Details below ā€˜Write Controlā€™ input box was a dropdown to a variable (I thought it was a heading for the parameters that followed), so the only way I could get a 1s simulation to run was to change Write control to ā€˜Adjustable runtimeā€™ and that automatically changed the hidden ā€˜Write Intervalā€™ value to 1sā€¦ :face_with_raised_eyebrow::face_with_raised_eyebrow::face_with_raised_eyebrow:

I just did not realize the consequences of doing so back thenā€¦ (but I did not seem to consistently get Out of Memory errors, just hang-ups). BTW, no hangups :slight_smile: since I have seen the light and put write back to length of sim (which BTW I have been running lengths at 400s lately, I figure if not converged at 400s, why go to 1000s).

And then it just hung around since I have been duplicating simulations to act as a template just so I donā€™t enter everything again. Maybe there needs to be various ā€˜templatesā€™ for simulations that you can save and rename :wink:

What would ever be the reason to have a sim ā€˜stepā€™ at anything but 1s?

103

No scenario in a steady state simulation that I can think off, really applicable in transient simulations, where time step size makes a big difference, not only to the result accuracy but the stability of the simulation.

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104

I see that your Custom Inlet/Outlet Boundary condition also uses customized values for k=9.126000000000002e-9 and omega=0.006166216216216216 while the default values for k and omega in my Initial conditions are k=0.000001612 and omega=3.375.

To be consistent with all my other simulations in this project, I assume that I DO NOT use the values you used.

And is it sufficient to just leave them as initial conditions and not also set them in the Custom boundary condition?

Thanks Dale

105

Hi @DaleKramer!

There is a SimWiki post about that topic which might be interesting for you (it is from Darren btw :slight_smile: ): Defining Turbulent Boundary Conditions

Cheers!

Jousef

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