[jaiswal]

Hi All,

What is meant by convective outlet boundary condition?

I am trying to implement Spalart Almaras Turbulence model in Navier-Stokes solver.
The BC's for SA model are as follows:

1.) At wall : .

2.) Freestream : Ideally

3.) Outlet : convective outlet

Can anyone please explain me what is meant by convective outlet boundary condition pls?

[Mehrez]

Originally Posted by jaiswal

Hi All,

What is meant by convective outlet boundary condition?

I am trying to implement Spalart Almaras Turbulence model in Navier-Stokes solver.
The BC's for SA model are as follows:

1.) At wall : .

2.) Freestream : Ideally

3.) Outlet : convective outlet

Can anyone please explain me what is meant by convective outlet boundary condition pls?

Hi,
it means, dU/dt+U.gradU=0
Mehrez

[leflix]

no sorry Mehrez it does not mean what you mentioned. Convective outlet boundary condition is du/dt+C*du/dn= 0
here d/dt is partial derivative operator d/dn is the spatial derivative in the normal direction of the boundary (on a vertical boundary it would be d/dx)
C is a celerity which is computed from the velocity. It may be the mean velocity as an example.
This model comes from equation of wave. The velocity is seen as a wave which is convected out from the domain and C is computed such a way this wave cannot come back in the domain after it exits (non reflective boundary condition).
See Orlansky boundary condition.

[Parth04]

what about pressure boundary condition in such case???????