Anisotropy with a General Concentration Dependence

We now abandon the exponential variation on which we have focussed for a more general concentration dependence. In particular, if 

Contours of constant j and w can again be drawn by the parametric formulas 

as we should expect, u = v for j = 0 and, since 4 2 0, the domain j + jM (w) s 0 is mapped onto the positive quadrant of the u, u-plane. The curves of constant w are again parallel and are given by 

Stern and Saxena (1980,1982) have used a total concentration of vapor, c(, of the form 

By working with cm within the membrane and using Eq. (35) at the surface we can directly apply the results obtained above. While permeability minima may arise, we have chosen to work directly with the flux. 

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