Well, I was just querying because the Full Res is not the same as converged, it is the same as the Not Full Res simulation of the same mesh that the Full Res was made from (ie 1,239.387v) and I think it is a significant difference.
I was thinking a line on the surface of the geometry that shows a line of S points from this image:
That is what I want to know (and see in 3D), I am sure it does behind the trailing edge and maybe a little before the TE, but how much
Maybe not a line but just a surface color for attached (green) and detached (red).
And then show some nice little particle traces in the air around it
Sorry, I re-read this several times, I think my brain has shut off. To clarify, the same mesh run in full res and wall model are significantly different? which simulation/runs can I look at, maybe I looked at the wrong ones.
Oh yes, I think doable, never done before but doable. So I think by doing a dot product on the surface tangents with the near-field velocity, those that face the âwrong wayâ we could highlight as -1 and those the correct way as 1 then visualise with a surface colour map between -1 and 1. This needs paraview, I think we should test on one with definite separation where visually we can see the recirculation. Any chance you could run one at say 15 degrees AoA? or do we need more for this foil?
Well, this ties in with the full res simulation. If the results are significantly different then the Y+ in the blue is an issue I would say, but if not then it doesnât matter.
AHA moment⌠so you are saying that BECAUSE the full res results are same as not full res on the same mesh, that the layering is GOOD.
I thought that the full res would give the best converged results, sorta like a mesh with infinite cells could do somehow, but full res was not used all the time due to excess core time to do it.
I think I understand now, a dangerous thing
I think at even maybe 12 degrees would show separation sorta between LE and TE, 15 would show close to LE.
I will make a geometry for that as I really donât like the standard way of changing air inlet vector (but that is another topic for you to convince me it is OK to change inlet vector without undue wall influence (especially high aoaâs)).
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.
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?
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?
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.
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 componentsâŚ
This input method could be one click away (Input Selection Box: Cartesian or Angle)
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.
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.
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.
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