OUTFLOW boundary condition for scalars
 

I am working on building a turbulence model SST-kw . My base code is openfvm
For this I need to solve the scalar k and omega equations
My BCs are velociy inlet and OutFLOw
How do I implement OUTFLOW condition for scalar (k & w)
My problem flow past a sphere , incompressible ,solver petsc distributed solver
What I did was I put the cell-face k is equal to value of the Cell centre for the outflow boundary cell
is this approach correct

In outflow BC for velocity, (u,v,w) velocity is interpolated based on pressure but for scalars (k & omega) is there any equations of similar type

Thanks