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 Nikhil June 21, 2007 12:07

Supersonic flow over flat plate

I tried to get the solution for the supersonic flow over a flat plate. After about 700 iterations, my horizontal velocity started turning negative towards the trailing edge and solution became imaginary.

Can anybody please suggest the mistake...

 Ahmed June 22, 2007 02:47

Re: Supersonic flow over flat plate

Years ago, I solved this same problem, reduce cell size to around 0.01 mm in the flow direction (you can have more than that in the normal direction) and the corresponding time step

 Mani June 22, 2007 07:51

Re: Supersonic flow over flat plate

>reduce cell size to around 0.01 mm

What if the flat plate is 0.02 mm long? Have you heard of non-dimensionalized variables?

 Ahmed June 22, 2007 08:11

Re: Supersonic flow over flat plate

and you, have you ever spent 3 month writing a C-programme to solve this problem? and that was 15 years ago, learn to be modest?

 archeoptyrx May 20, 2013 02:13

I will try for it . My cell size is 1.42*10-7 . I have the same problem. Plate length is .01mm with 70*70 grid points.

The code seems to work good results for M=4 . for M>4 it fails and gives me imaginary solutions .

Does increase in Velocity has some effects on the grid ?

Should i increase the grid points to 80*80 ?
Any suggestion will be of great help .

Thanks

 ufocfd May 20, 2013 06:03

Quote:
 Originally Posted by Nikhil ;50337 I tried to get the solution for the supersonic flow over a flat plate. After about 700 iterations, my horizontal velocity started turning negative towards the trailing edge and solution became imaginary. Can anybody please suggest the mistake...

Maybe you have a sub-sonic outlet boundary, and you need to change it to supersonic boundary type ?

 archeoptyrx May 20, 2013 12:48

The outlet is just an extrapolated value from the interior points . So i think thats not a problem

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