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-   -   fluent and shock wave (http://www.cfd-online.com/Forums/fluent/28310-fluent-shock-wave.html)

huong March 15, 2001 08:12

fluent and shock wave
 
I did a 2D simulation on NACA 0012, Mach=0.82, 2 degrees incidence and perfect gas assumed. The problem is the shock location seem to happen about 10 % rearward as compared to the experimental and the worst is the pressure on the top surface in higher then the lower at the trailing edge which is contradicting the experimental's. please advice , thanks.

Dave Smith March 15, 2001 20:12

Re: fluent and shock wave
 
have you checked the Reynolds number of the flow.

the experimental data must quote a Reynolds number, and this must be modelled correctly.

this is done via the viscosity is an ideal gas is used.

huong March 19, 2001 00:27

Re: fluent and shock wave
 
hai, dave,

unfortunately, i don't have the Re for that particular experiment. however, I did try to change the Re ranging from 1xE6 to 1xe7, the result s remain the same with little changes. pls advice further. thanks

Dave Smith March 19, 2001 11:44

Re: fluent and shock wave
 
well the reynold number will have a severe effect on the shock loaction - try a reynolds number of the order 1000.

is the flow laminar or turbulent? if it is laminar the shock location should be correct, if turbulent it will have some inaccuracy depending on the model used.

is the pressure coefficent on the leading edge underestimated by fluent, this will cause the shock to move backwards.

it sounds like you are getting a very powerful shock so check the AoA and mach number also. Finally the ends of the pressure distribution should 'slightly' cross, as this is caused by the kutta condition employed by fluent, yours sounds more extreme indicating a strong shock.


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