# airfoil boundary condition

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 June 25, 2006, 12:21 airfoil boundary condition #1 Bounecer Guest   Posts: n/a hello all; I'm writing a computer code simulating flow about an airfoil, in case of 2D, incompressible, laminar and viscous flow.Reynolds number equal 2x10**3. Governing equations were adimentionalised by setting U=u/ue and V=v/ue, .......(ue is the upstream velocity) My question is about the boundary condition at upstream, is it U=1, or U=Re*visc/C Re: Reynolds number Vis: Kinematic vicosity of air C: Corde Thanx

 June 25, 2006, 23:39 Re: airfoil boundary condition #2 ganesh Guest   Posts: n/a Dear Bouencer, The upstream BC should be U = ue/ue = 1. The kinematic viscosity would then become Vis/Re, after non-dimensionalisation. Regards, Ganesh

 June 26, 2006, 10:27 Re: airfoil boundary condition #3 Dominic Guest   Posts: n/a Yes, Ganesh is right. Also, to add more : u said: " is it U=1, or U=Re*visc/C" It should be u=Re*visc/C and not 'U'. Here 'u' has dimensions. But U doesnt have. If u calculate 'u' based on the above Re and divide by ue, u shud get '1' at the upstream. regards, Dominic

 June 26, 2006, 14:29 Re: airfoil boundary condition #4 Bounecer Guest   Posts: n/a Thanx Ganesh, Please i've an other question: I'm using C-grid generation, so the upstream side in physical domain become the top side in computational domain, how to write the boundary condition U=1 (condition in physical domain in terms of cartesian coordinates) in computational domain where i must express U in terms of the new curvillinear coordinates ksi and eta

 June 26, 2006, 23:43 Re: airfoil boundary condition #5 Dominic Guest   Posts: n/a Hi, If U' represents the solution in computational domain, and U in the physical domain then, U' = [T] U, Where [T] = | d(x,y)/d(ksi,eta) | T(1,1)=dx/dksi ; T(1,2)=dy/dksi ; T(2,1)=dx/deta; T(2,2)=dy/deta; Here [T] is the Jacobian of the transformation.. Knowing U, you can compute U'... regards, Dominic

 June 27, 2006, 05:17 Re: airfoil boundary condition #6 Bounecer Guest   Posts: n/a thanx Dominic; If y're agree i'll send you the mathematical model in cartesian and curvillinear coordinates with descriptions, the finite volumes steps discretization and my code program in Fortran.

 April 12, 2012, 12:06 iii #7 New Member   fatimah Join Date: Sep 2011 Posts: 5 Rep Power: 8 hai all.. im also writting computer code using fortran.. i try to simulate airfoil in c-grid.. my problem is.. i not sure the boundary condition at double connected grid (after the trailing edge).. hope u all can help me.. thanks..

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