Drift/diffusion conduction model for flow electrification

A drift/diffusion model is developed for bipolar conduction with molecular charge recombination and generation process in a turbulent liquid dielectric between rotating concentric cylindrical electrodes. The analysis is used to model electrification in the turbulent flow of a Couette charger of coaxial cylinders with open-circuited, short-circuited, or DC voltage energized electrodes at various inner electrode rotational velocities. Specific electrode wall charge densities are found which yield near self-consistent solutions with measurements of open-circuit voltage, short-circuit current, and turbulent core charge densities. Typical experimental measurements indicate wall charge densities much larger than the equilibrium charge densities of each carrier, invalidating a quasiequilibrium ohmic conductivity model as the local conductivity near the wall is enhanced over the equilibrium conductivity. The enhanced conductivity is derivable from the numerical solution to the nonequilibrium drift/diffusion problem.<>