In his CFD textbook, Patankar [Ref. 5] replaces the left-hand side of Eq. (8.119b) and (8.119c), respectively,

Question:

In his CFD textbook, Patankar [Ref. 5] replaces the left-hand side of Eq. (8.119b) and (8.119c), respectively, with the following two expressions: Are these equivalent expressions, or are they merely simplified approximations? Either way, why might these forms be better for finite-difference purposes?

In his CFD textbook, Patankar [Ref. 5]