NE461 Lecture Notes - Lecture 3: Horse Length, Analyte, Flow Cytometry

• School: University of Waterloo
• Department: Nanotechnology Engineering
• Course: NE461
• Professor: Juewen Liu

Document Summary

Lecture 3 small re and large pe number cases. L is the characteristic length that a chemical species has to diffuse and di is the diffusion coefficient of that species. Pe compares the time of diffusion (which strongly depends on the particle property, reflected by d), and the time of convection (which is independent of the particle property, mainly carried by the fluid). The mass transfer peclet number of each species is defined as pe = (l2/di) / (l/v) = vl/di. The peclet number is a measure of the relative time of diffusion as compared to the convection term. Peclet number is applied to each chemical species. In a flow, v and l are usually fixed and different species can differ quite a lot in d as shown in the table below. Diffusivities for dilute analytes in water at 25 qc (unit of d = [m2/s]).