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Old   June 25, 2006, 12:21
Default airfoil boundary condition
  #1
Bounecer
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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
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Old   June 25, 2006, 23:39
Default Re: airfoil boundary condition
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ganesh
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Dear Bouencer,

The upstream BC should be U = ue/ue = 1. The kinematic viscosity would then become Vis/Re, after non-dimensionalisation.

Regards,

Ganesh
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Old   June 26, 2006, 10:27
Default Re: airfoil boundary condition
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Dominic
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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

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Old   June 26, 2006, 14:29
Default Re: airfoil boundary condition
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Bounecer
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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
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Old   June 26, 2006, 23:43
Default Re: airfoil boundary condition
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Dominic
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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

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Old   June 27, 2006, 05:17
Default Re: airfoil boundary condition
  #6
Bounecer
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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.
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Old   April 12, 2012, 12:06
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fatimah
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imah is on a distinguished road
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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