NE461 Lecture Notes - Lecture 9: Molecular Dynamics, Chemical Species, Electric Field

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

Document Summary

Chemical species are transported through fluid systems owing to both diffusion and convection. Species diffusion refers to the net migration of species owing to brownian motion in the system. The thermal energy in the system leads to species motion in random directions. The effect is a net migration of species away from high-concentration regions and toward low- concentration regions. In addition to diffusion due to thermal motion, the motion of chemical species due to fluid flow and electric fields (i. e. , convection) also leads to a species flux, as the species are carried along when the fluid moves. In the presence of electric fields, though, charged ions move in response to the coulomb force they feel in that electric field a process termed electrophoresis. In microfluidics we deal with an aqueous system. Water is a high dielectric liquid and has ions, charges that also have freedom of motion.