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-   -   transonic airfoil in Fluent (http://www.cfd-online.com/Forums/fluent/32600-transonic-airfoil-fluent.html)

Luis November 26, 2003 10:33

transonic airfoil in Fluent
 
Hi everybody, I´m a student who is trying to solve a transonic flow over a SC(2)0714 airfoil. I´m using Fluent 6.0 with the next conditions: coupled implicit solver; Sparlat-Allmaras; energy equation on; operating pressure=0; Pressure far field boundary condition around the airfoil; Mach=0.8; Gauge pressure=101325 Pa;temperature 300k; Sutherland Law; The problem is when I try to iterate, it just doesn´t work and writes the next message: Divergence detected-temporaly reducing Courant number to 0.5 and trying again... divergence detected-temporaly reducing Courant number to 0.05 and trying again... (five times) Error:Internal error at line 800 in file "rp_mstage.c" divergence detected in AMG solver Error Object:()

I´ve tryed whith lower relaxation factors and whit residuals, and also changing Courant number, and it still doesn´t work. I need some help please.

Thank you to anyone Luis

ccc November 27, 2003 03:51

Re: transonic airfoil in Fluent
 
hi Luis,

try to enlarge your computational domain and it may work.

good luck.

Luis November 29, 2003 13:12

Re: transonic airfoil in Fluent
 
Thank you for your answer ccc, My domain is 20 times the chord of the airfoil, and it still doesn´t work. Any ideas? Thank you.

Charles Crosby December 1, 2003 04:55

Re: transonic airfoil in Fluent
 
Try starting with first order differencing, running to convergence and then set second order and converge again.

ccc December 1, 2003 06:34

Re: transonic airfoil in Fluent
 
hi Luis,

I am sorry to hear that it did not work.

Anyway, since there is a case very similar with yours in fluent tutorials, I do not think it is a big problem.

first, refering to this example and finding difference will be helpful.

second, you should check the flow field, for example, plot contours of pressure, to see if there is something physical irrational. This maybe helps you find where the problem is.

third, I think you should pay attention to the grid.Sometimes, high screw grids make computation blow up.

Good luck.


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