Page 119 - gas transport in porous media
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112
                           Second Problem for Species A
                                     3                                                 Whitaker
                                           γ      γ −1     γ
                               0 =∇ ·  D AB     D AB     D AA   ∇b AB +∇b BB            (6.219a)
                                                                                         4
                                         γ −1     γ                  γ −1       γ

                                  +  D AB     D AC   ∇b CB + ... . +  D AB     D A, N−1   ∇b N−1, B

                                                                  γ −1      γ
                                 BC.    − n γκ ·∇b AA − n γκ ·  D AA     D AB   ∇b BA  (6.219b)
                                                   γ −1      γ

                                        −n γκ ·  D AA     D AC   ∇b CA − ... .
                                                    γ −1        γ

                                        − n γκ ·  D AA     D A, N−1   ∇b N−1, A = n γκ ,  at A γκ
                               Periodicity: b DB (r +   i ) = b DB (r) ,  i = 1, 2, 3 ,  D = 1, 2, ... , N−1
                                                                                       (6.219c)
                           Third Problem for Species A
                                                           etc.                         (6.220)

                             N − 1 Problem for Species A
                                                           etc.                         (6.221)

                           Here it is convenient to define a new set of closure variables or mapping variables
                           according to

                                                γ −1     γ           γ −1      γ

                               d AA = b AA +  D AA     D AB   b BA +  D AA     D AC   b CA  (6.222a)
                                                  γ −1        γ

                                     + ... . +  D AA     D A, N−1   b N−1, A
                                          γ −1      γ                γ −1      γ

                               d AB =  D AB     D AA   b AB + b BB +  D AB     D AC   b CB  (6.222b)
                                                   γ −1        γ

                                     + ... . +   D AB     D A, N−1   b N−1, B
                                             γ −1     γ           γ −1      γ

                                 d AC =  D AC     D AA   b AC +  D AC     D AB   b BC  (6.222c)
                                                            γ −1        γ

                                       + b CC + ... . +   D AC     D A, N−1   b N−1,C
                                                           etc.                     (6.222n − 1)
                           With these definitions, the closure problems take the following simplified forms:

                           First Problem for Species A
                                                             2
                                                        0 =∇ d AA                      (6.223a)
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