Permeability coefficient pointwise

If Gy = Gy- is to be the molar flux of a component /, it follows that the units for the pointwise permeability coefficient P, necessarily are... 

In mixtures, the pressure dimension in the permeability coefficient becomes the partial pressure pp. That is, the pointwise permeability coefficient in a mixture will have the units or dimensions of... 

The practice here is not to attempt to adapt symbols to distinguish one kind of permeability coefficient from pother (e.g., a pointwise coefficient Pj from an overall coefficient, say P-). Rather, as noted earlier, all coefficients are simply denoted P, to be further distinguished by context of usage, with the required units or dimensions and magnitude dictated by that usage. 

The membrane thickness Aw may, of course, be incorporated into the pointwise diffusion coefficient D, or the equivalent permeability coefficient P to obtain the overall coefficient. 

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