Consider laminar flow of an incompressible, constant-property fluid in a tube. Assume that mass transfer takes place between the tube surface and the fluid, in which the transfer rate of the...

Consider laminar flow of an incompressible, constant-property fluid in a tube. Assume that mass transfer takes place between the tube surface and the fluid, in which the transfer rate of the transferred species is low. Perform a scaling analysis on the mass-species conservation equation and show that axial diffusion in the fluid can be neglected when