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The backward form of the equations for the boundary conditions at the
soil surface are
Backward direction: z = 0
j = 1
energy: (A-16)
dzj Bi 1 + KC2
TjrHl X" j(1-KC2+i) Rn,r-l+ (1-KC2+Bi) Tanl+ (1-KC2+Bi)Tj+1,nrl
water: (A-17)
dzj
0j,ln+ = Oj+l,n+1+ DL,j P+1
vapor: (A-18)
Bim 1
Pj,n+ = (1 + BiJ Pva,nl+ + (1 + Bim) Pvj+1,n+l
The above equations were used to represent the partial differential
equations which describe the energy and mass transfer within the soil.
After a complete cycle through the nodes, from node 1 to node nc, then
from node nc back to node 1, all of the equations had been solved using
the most recent values of the state variables.