I l*, d dIl 1 d
A/AA fdx-+ AiAk dy-+ AAk dz- +fdVj 1,- f(v,)^
Eq. (5) can be rewritten in terms of the current entering/leaving a cell as
.|., -J +./ I - J J ., -J ,
+ . fdV D' - (v )fdV
The cell-averaged flux is given by
S- - - -dV D
f fdxf dz AyA,
dJ - tz J -...- 5J;-.-.
Using Eq. (7), Eq. (6) reduces to
11 + JI + -1 - I +J1,.", ( Jl ]-"
k
The current formulations are given by