It is assumed in the derivation of this equation that the pressure and the diffusion coefficient are constant.
In general, the diffusion coefficients of the two materials in each other are not the same.
Using an empirical formula based on his data, Buckingham was able to give the diffusion coefficient as a function of air content.
Thus the diffusion coefficients had to be localized, or mapped on to the tissues.
In the anisotropic media, the diffusion coefficient depends on the direction.
The symmetric matrix of diffusion coefficients should be positive definite.
Only the diffusion coefficients for the binary and ternary case can be determined with reasonable effort.
D is the diffusion coefficient of the stationary phase.
The required diffusion coefficients, however, appear to be larger than are observed in the real ocean.
It is linked to the diffusion coefficient by the equation: