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 MATT September 1, 2005 10:55

FLOW OVER COMPLETE AIRCRAFT

IS PHOENICS CAPABLE TO SIMULATE THE FLOW OVER COMPLETE AIRCARFT?

IF SO, THEN HOW?

THANKS

 Mick September 1, 2005 16:16

Re: FLOW OVER COMPLETE AIRCRAFT

Yes, I have found that high speed flows are quite visous though. There will be some publications in the PHOENICS journal I am sure. There is a F1-VWT (Virtual Wind Tunnel) variant of the software that might lend itself more easily to problem set up. I must admit that I have not used this variant yet. Essentially Import CAD geometry, crunch a very very fine mesh close to the surface, solve for the "static temperature" formulation, choose appropriate turbulence model and set appropriate boundary conditions maybe for total pressure and total temperature. Experts and UNI Depts who specialise in aerodynamics tend to have their own in-house codes specificially designed for this purpose as this is I believe quite a niche problem area.

 Mick September 1, 2005 16:23

Re: FLOW OVER COMPLETE AIRCRAFT

vicious not visous, wrong spelling sorry!

 MATT September 4, 2005 00:53

Re: FLOW OVER COMPLETE AIRCRAFT

thank you for your info.

one more thing, do u know any paper or website that i can refer to.

 MATT September 4, 2005 05:18

Re: FLOW OVER COMPLETE AIRCRAFT

cartesian vs bfc, what the difference? in my case which one should i use?

 Mick September 4, 2005 13:29

Re: FLOW OVER COMPLETE AIRCRAFT

hello, Cartesian mesh-> This would mean that the solution domain was represented by brick elements. However at the surface of your aeroplane the curvature would be handled by these bricks being cut so that part of the 'brick cell' would be air and the other part solid aeroplane. The aeroplane would come from a CAD geometry and the mesh thrown over the solution domain with the cut-cells being automatically picked up by the code.

BFC grid -> Fits 'body-fitted' cells around your aeroplane so that the cells are skewed to represent the geometry of the aircraft. The geometry would be represented by points lines and surfaces from which meshed frames can be generated. This might work well if a decent mesh can be made. Very loosely speaking if the cells are not at a skewed angle of < 30 degrees (from normal), although solutions can be obtained on grids were cells are considerably more skewed. With BFC creating the mesh is a considerable part of the overall solution time.

Other Pros and Cons to be considered are that with BFC, (to my knowledge), all the turbulence models should be available, however with the cartesian cut-cell method only the high-Re KEMOD turb models have as yet been developed to work with the cut cells.

As for papers, I will try and find some references when I get near to some PHOENICS journals.

 MATT September 5, 2005 22:50

Re: FLOW OVER COMPLETE AIRCRAFT

thanks for your info.

1)cartesian grid, then use elliptic staggered . 2)bfc grid, then use elliptic gcv.

is it the correct setting?

 mick September 6, 2005 08:25

Re: FLOW OVER COMPLETE AIRCRAFT

1/ yes absolutely. 2/ Should try both, Elliptic-Staggered and GCV, its just a click of the button through the menu panels.

 MATT September 12, 2005 08:17

Re: FLOW OVER COMPLETE AIRCRAFT

Do u have any ideas about the solution domain size compare to aircraft size? Is it ok if I set the aircraft size as 5%, compared to the domain size?

 PattiMichelle October 27, 2005 13:43

Re: FLOW OVER COMPLETE AIRCRAFT

Hi Mick - do you know if the higher-order schemes were fixed in 3.6.0?

 tom November 1, 2005 05:47

Re: FLOW OVER COMPLETE AIRCRAFT

Patti, I have the corrected earexe that CHAM sent me following the v3.6.0 HOCS fix. I'll send it to you if you want it! Tom

 Patti Sheaffer November 1, 2005 12:07

Re: FLOW OVER COMPLETE AIRCRAFT

That's OK - I just wanted to make sure you had it...

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