A friend is trying to understand a paper which discusses the diffusion of proteins through milk. Rather than listing a diffusivity (with units [Length]^2/[Time]), the paper lists the 'diffusion rate' of the proteins through the liquid, in units of mm/hr (i.e. [Length]/[Time]).
We can't make heads or tails of this. I was wondering about some sort of 'average front propagation velocity', but I'm not sure how that would be defined, as a diffusion front's velocity can change over time, and depends on the geometry, concentrations, etc.
Has anyone run into this terminology before?
Thanks