# Supersonic flow over flat plate

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 June 21, 2007, 12:07 Supersonic flow over flat plate #1 Nikhil Guest   Posts: n/a 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...

 June 22, 2007, 02:47 Re: Supersonic flow over flat plate #2 Ahmed Guest   Posts: n/a 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

 June 22, 2007, 07:51 Re: Supersonic flow over flat plate #3 Mani Guest   Posts: n/a >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?

 June 22, 2007, 08:11 Re: Supersonic flow over flat plate #4 Ahmed Guest   Posts: n/a 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?

 May 20, 2013, 02:13 #5 Member   sandy Join Date: May 2013 Posts: 91 Rep Power: 11 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

May 20, 2013, 06:03
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Giles Richardson
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Location: Cambs UK
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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 ?

 May 20, 2013, 12:48 #7 Member   sandy Join Date: May 2013 Posts: 91 Rep Power: 11 The outlet is just an extrapolated value from the interior points . So i think thats not a problem