Key points are not available for this paper at this time.
The combined effect of diffusion, and of convection by Poiseuille flow, on the distribution of a small quantity of miscible additive injected into a tube of radius a, is to spread it longitudinally with a Taylor “effective diffusion coefficient”, to an approximation that is good at times greater than about 0.5a2/D (Bailey and the introduction indicates the relevance of the new theory to work (Caro, 1966) on tracers used in study of the blood circulation.
M. J. Lighthill (Sat,) studied this question.