Haha! well as long as you use an inlet-outlet condition all around the wing its fine, I could link you an example?
Best,
Darren
But what if the air that gets to the wing has already been influenced by some air that was already bounced off a âwind tunnelâ wall in front of the wing? (maybe I should see your example but the ones I have seen made me question the method)
Here is my NACA0012 project, itâs my playground for trying weird things so excuse the mess. The best example is validationMK2, to get an idea of setup (ignore the failed runs 
)
But essentially the walls above, bellow, upwind and downwind are set to inlet-outlets, where they donât âknowâ about what lies outside them (such as surrounds or wind tunnels) they âknowâ that air is travelling in a direction that is going into the domain, if flow exits the domain, then it acts as if it just moves out of it, to us that is zero gradient. So there will be no deflection from any wall external to it, nor will the walls themselves make the flow behave any differently to if they were orientated with the flow.
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Maybe that wall setup should be called an open door instead⌠
It is so nice to able to do things here that canât be done in the real world
I will duplicate your wall and inlet setup and run a 12aoa simulation 
Thanks,
Dale
Haha, yes, a true âcontrolled environmentâ I would describe it as 
I just noticed also you were getting errors saying that the instance ran out of memory. This is because you are saving too many timesteps. Since we are only interested in the converged results, if you set it to run to 1000s then the time write intervale can also be 1000s saving only the final results, this saves download time, and allows the most significant data to be saved. When I view your project, it says you saved every 1s, and ran for over 300s and only saved 38 steps before running out of space, so I donât know what data is present, however, I would guess its the first 38 steps. Does that make sense?
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Yes it makes sense I thought I was still just using default values for simulation control, I thought I would figure it out later, I guess now is later 
I was caught by the hidden âDetailsâ dropdown on the write value until nowâŚ
I will correct.
How is the âAdjustable Runtimeâ write control any different from âTimestepâ?
RE: NACA0012
- Why are there 2 symmetry âwallsâ? Does this simulate infinite span?
- How do you make those symmetry âwallsâ act like inlet/outlets for some sideflow in air inlet vector?
- And the big question⌠why cant I input my air velocity vector as magnitude and angle about each axis? It is dark ages to me to have to break my vector down into x,y,z components on a calculator, or am I missing something?
Thanks,
Dale
This to me makes more sense when thinking about a transient simulation time steps would be the number of steps between the written times, whereas the adjustable runtime is the interval between written steps in seconds, one is a number the other is a quantity of time. for steady state with a 1s interval, 1000s = 1000 timesteps so both are the same.
Yep exactly
ooo, bit tricky that one. I think the best solution would be to make a periodic boundary condition between the two for my case, for your case (a non 2D shape) we couldnât do that, full geometry would be needed removing the symmetric assumption.
The only ease there would be that we donât have to calculate, we would then require 4 inputs, not 3. But I suppose it makes sense to offer this as an option.
Best,
Darren
So is this why my runs were hanging yesterday, writing results every second?
I must have unknowingly changed it thinking it would do as I expected, not hang the run
Possibly yes, if there was a lot of results to reconstruct at the end. Didnât know that then though 
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I was thinking just like this (rather do those 4 by the mega keypressâs and brain power to get it right, with my calculator )
magnitude ____ (+ is away from origin)
x angle ____ (ccw from x+)
y angle ____ (ccw from y+)
z angle ____ (ccw from z+)
Default all to 0, then for 12 degrees aoa I put in two numbers and no chance me getting +/- vector component errors and mis-inputting and calculating the vector components⌠
This input method could be one click away (Input Selection Box: Cartesian or Angle)
Dale
Wow this is SO relevant⌠I have been hanging runs all day on my whole plane project 
Thanks, big like on this oneâŚ
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Thinking about it, not sure this would work, fine for planar cartesian aligned inlet, but what if curved or not aligned? to be robust it would need telling the base direction and then angles 6 inputs! but yes if a default of say direction 1,0,0 and angle 0,0,0 was assumed this might be a quick setup option.
Best,
Darren
Iâll let you worry about the curved input, how do you do that into just x,y,z inputs anyway?
I think that the above would handle the vast majority of angles needed for the aerodynamics discipline 
Not aligned cases means you should get your values from a CAD program anyway and I would EXPECT to have to do that in that case, but not the basic case.
Not sure why this is a requirement, doesnât the (ccw from ?+) take care of it more generally?
I can get the right quadrant and direction in my head just thinking about my 4 inputs.
For my case 12aoa would be magnitude +2376 and x angle +12
I just made a little spreadsheet that looks like my suggestion and that took my calculator and a lot of the brain power away from my problem⌠
Hi Dale & Darren and sorry to crash into your exciting discussion.
Dale mentioned that he expects boundary layer separation which means that no wall functions should be used because the log-based wall functions do not correctly predict the profile. Directly resolving the viscous sublayer is strongly recommended in this case - not sure if Darren mentioned it though.
Best,
Jousef
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?
I finally figured how write control got changed to 1s and then why it just hung around 
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 âWrite Controlâ 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 âAdjustable runtimeâ and that automatically changed the hidden âWrite Intervalâ value to 1s⌠
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 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 donât enter everything again. Maybe there needs to be various âtemplatesâ for simulations that you can save and rename
What would ever be the reason to have a sim âstepâ at anything but 1s?
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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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
Hi @DaleKramer!
There is a SimWiki post about that topic which might be interesting for you (it is from Darren btw ): Defining Turbulent Boundary Conditions
Cheers!
Jousef
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