The governing Equation 22–1, Equation 22–4, and Equation 22–11 have the form of convection diffusion equations and are discretized using a finite volume scheme of Patankar [508].

The convective terms in Equation 22–1, Equation 22–4, and Equation 22–11 are discretized using first order upwinding, central differencing or the DISC scheme [550]. While the first two schemes are well described in the Ansys Fluent User's Guide, the reader is referred to [550] to learn more about the DISC scheme. It is the recommended scheme because it provides outstanding numerical stability combined with second order accuracy. The diffusion terms are discretized with second order accuracy. All other terms are treated as source terms and linearized according to Patankar [508].