hans186 
March 31, 2013 06:38 
viscosity term in discetrization momentum equation
Hi all,
I have a question regarding the discretization of the momentum equation for use in a simple solver.
I'm having trouble in understanding where the viscosity term goes. I'm currently reading Versteeg 2007 , An introduction to CFD, and can't figure it out.
At some point the momentum equation, including the body surface forces caused by viscosity is discretisized to:
As I understand it, the viscosity term is not present here, coefficients only have a velocity and density dependence. I can't seem to locate a viscosity in the source term,S ,either.
If find that on the web it is often pointed out that the discretization is similar to that of the general transport equation where the viscosity term can be handled equal to the diffusion term and the velocity term to the property term. In this case the diffusion term is preserved in the discretization, why than not (or at least lost to me) in the momentum equation?
Can anyone explain what i'm missing or point me in a direction where i can find some answers?I would be very happy to find the complete derivation of the discretization of the momentum equation so i can see what's happening step by step.
Kind regards,
