implementing boundary conditions

Andreas Abdon

Hello everybody!

I'm implementing boundary conditions on a user scalar equation in user fortran subroutine USRSRC. I want to assign the scalar a value in the near wall cells. The manual recommends the following procedure:

SP=-c SU=c*value AM=0 for all faces

where c is "set equal to approximately the maximum flux in the CV.. .. to stop potential errors due to the Rhie-Chow terms." (quote). I have tried this approach and also different constant values of c and found that it may distort the solution seriously, especially when the flux (velocity) is close to zero. Does anybody have a recommendation how to proceed? Is a large (1.0E10) value of c "safe" to use?

Greetings

Andreas Abdon

Div. Heat Transfer Lund Institute of Technology Box 118 22100 Lund Sweden