# Modelling enhanced diffusion

Write for the concentration of the chyme. The partial derivative measures the rate of change in the concentration with respect to time. As before, write for the velocity of the chyme (with its eddies). The equation modelling enhanced diffusion is

Here It represents the motion of the drug due to the convection in the chyme. The term is defined as It represents the motion of the drug due to diffusion through the chyme. In this expression is a constant called the coefficient of molecular diffusion.