where \({v_{l},\ H}_{B},\ N_{P}\), and \(\varepsilon_{i}\) indicate the liquid velocity, column height, number of theoretical separation plates, and interparticle voidage, respectively.
It is worth noting that the axial dispersion (mixing) usually happens when a fluid flows through a packed column such as ion-exchangers (Gu, 2015).
In order to see where to include axial dispersion in the bed model, the dimensionless Peclet number is employed which quantifies the degree of the dispersion introduced into the system.