Eulerian formulation for the triboelectric charging of polydisperse powder flows

We propose an Eulerian formulation for the triboelectric charging of powder flows. Recently, continuum descriptions of the charging of monodisperse and bidisperse powder appeared. Now, we propose the first Eulerian formulation for this type of flows that can fully account for polydisperse particle size distributions. To this end, the joint particle size, velocity, and charge distribution function are solved through the direct quadrature method of moments. The newly established approach includes the uptake of electrostatic charge by the particles when contacting a solid wall and the exchange of charge in-between particles during collisions. The electrostatic field induced by the charge of the particles and the drag forces of the surrounding gas affects the particle dynamics. Test cases of two-dimensional steady channel flows demonstrate the charging of the flow from the walls toward the center and in the downstream direction. Further, the method predicts the effect of variations of the particle size and initial velocity distribution and the charge diffusion coefficient. The ability to handle polydispersity is a step toward the simulation of the electric charge buildup of real powder flows in full-scale technical applications.

Automated summary

In this study, an Eulerian formulation for triboelectric charging of powder flows is proposed, able to fully account for polydisperse particle size distributions. The approach involves solving the particle size, velocity, and charge distribution function through a direct quadrature method of moments, considering electrostatic charge uptake by particles when contacting a solid wall and charge exchange between particles during collisions. The method can predict the effect of particle size variations, initial velocity distribution, and charge diffusion coefficient on particle dynamics and charging of the flow.