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Meshing problem on aerodynamic simulation incorrect results

Anonymous

Meshing problem on aerodynamic simulation incorrect results

Anonymous
Not applicable

There are artifacts on the tail as well as select other places on this aircraft that impact the solution. I believe the root cause of this maybe the fact that  half the plane was designed than mirrored. I would like to know what I can do to solve this, and have attached the design study.

https://drive.google.com/open?id=1Nj-JU0isNEy9UzioZ4Wrzj6pYkj-VqLY

(attachment would not work)

I would also like some suggestions as every time I run the simulation a high velocity zone shows up in a different place. This is no reason that I can think of, and is many magnitudes greater than what should be possible.

This is also my first time using motion, so that maybe another problem.

CFD 2018

Windows 10

CPU  Intel(R) Core(TM) i7-7820X CPU @ 3.60GHz
RAM 16 GB

GPU
    AMD Radeon (TM) R9 380 Series
    Driver version:    22.19.677.257
    Driver date:    09/21/2017
    DirectX version:    12 (FL 12.0)
    Utilization    4%
    Dedicated GPU memory    1.5/4.0 GB
    Shared GPU memory    0.1/7.9 GB
    GPU Memory    1.6/11.9 GB

 

Proven ImpactProven ImpactStrange SquigglesStrange SquigglesI also dont know what this absurd high velocity zone isI also dont know what this absurd high velocity zone is

Thank you for your time.

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Anonymous
Not applicable

Hi @Anonymous

 

- Why is the reason you use motion? Why not using steady state flow only analysis? 

- Cell size seems to be bigger than the plane itself. It will never work. More work on the mesh needs to be done. 

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Anonymous
Not applicable

Thanks for the response @Anonymous 

I owe you an explanation of the project, so that you may be able to suggest better simulation alternatives.

This is a ground effect vehicle that I am doing simulation and prototyping on for Science fair, with this particular simulation I am attempting to determine the lift and drag Vs vertical displacement. I am currently at school so I will not be able to play around with cell sizing for a while, but when I do I will update you.

This simulation also served as a test for motion, I now hypothesize that it may be possible for me to create a really large air box, then run the GEV down it testing for stability in unpowered glide by adding an "effected by flow" motion across all axis and rotations, and an initial velocity in the direction of thrust. Bounds still confuse me, but I will figure it out later.

 

My Questions:

1: Would I need gravity for this, and as such would I have to update to CFD 2019?

2: What type of simulations would you run if you were in  my scenario? Ideally I have a simulation that demonstrates the ground effect, as well as the inherent stability of the design.

3: Is there a better way to automate this? Ideally I would like to run a simulation at one height,pitch,yay,roll, then at 1+ height,pitch,yay,roll. The perfect data output would be lift, drag, and then center of lift, drag. In some sort of relation to center of mass to make my life easier.

 

Thank you very much for your time!

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Anonymous
Not applicable

Update: Error is still present but smaller due to increased mesh resolution.

It still coincides with small squiggles that are highlighted when I select my plane geometry.

Attachment https://drive.google.com/open?id=1RkxJK_I6LzJ428LFt0iTtmorb8tvdxEV

PS I cant get attachments to work.

8m/s to Mach 18m/s to Mach 1better.PNG

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