Conditions under which dispersion of a solute in a stream of solvent can be used to measure molecular diffusion

Source abstract

Abstract It is shown that an assumption made in the author’s previous discussion (Taylor 1953) can be presented as a result of analysis. The conditions under which an approximate solution of the equations for diffusion in a moving fluid can be used to interpret longitudinal dispersion of a solute in a stream of solvent flowing through a tube is given as 4L/a - > a Ua /D > 6.9. Here U is the mean velocity, a the radius of the tube, D the coefficient of molecular diffusion. L is the length of tube over which appreciable changes of concentration occur.