XFLR5 vs CFD


#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 ‘Write Control’ 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 ‘Adjustable runtime’ and that automatically changed the hidden ‘Write Interval’ value to 1s… :face_with_raised_eyebrow::face_with_raised_eyebrow::face_with_raised_eyebrow:

I just did not realize the consequences of doing so back then… (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 don’t enter everything again. Maybe there needs to be various ‘templates’ for simulations that you can save and rename :wink:

What would ever be the reason to have a sim ‘step’ 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.


#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