# 2D External Aerodynamics

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 August 19, 2005, 20:13 2D External Aerodynamics #1 Miqdad Guest   Posts: n/a Sponsored Links Dear All, Can some one suggest the best model setup while performing an external aerodynamics problem in Fluent 2D. I am simulating airflow over a wing at subsonic speeds. I have used the Splart Allarmas turbulence model but cannot decide which solver to go for, I mean Implicit or Explicit. Secondly, I am plotting Cd and Cl while its solving and to be honest they are all over the place. I dont see any sign of convergence. Any suggestions on what I have done wrong? Thanks in advance. Miqdad

 August 19, 2005, 20:23 Re: 2D External Aerodynamics #2 Sham Guest   Posts: n/a Are you using steady or unsteady solver? Sham.

 August 20, 2005, 08:28 Re: 2D External Aerodynamics #3 Miqdad Guest   Posts: n/a Well, its not time dependent if that is what you are after. Its a steady state analysis.

 August 20, 2005, 15:49 Re: 2D External Aerodynamics #4 razvan Guest   Posts: n/a If you have been using coupled solver, switch to segregated solver and see what happens. Usually, if the velocities are low in most of the calculation domain, segregated solver will certainly behave much better. I simply don't see any other reason for such a simple analisys to not converge. Although, if you are simulating a high angle of attack flow, beyond the critical incidence of your wing, vortex shedding will surely give you difficulties and you will not obtain a steady solution. Best wishes, Razvan

 August 22, 2005, 15:16 Re: 2D External Aerodynamics #5 helper Guest   Posts: n/a If the case is set up as a steady problem, use either coupled implicit solver or segregated solver. When you see lack of convergence, try smaller under-relaxation factors (in the segregated solver) or CFL number (in the coupled solver).

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