Study of particle lifting mechanisms in an electrostatic discharge plasma

Although particle-laden electrostatic discharges are widely used in research as well as in industrial applications, the mechanisms of particle lifting for a particle initially at rest in such highly unsteady flows are not well understood. A multiphase plasma flow is modeled by solving the continuum conservation equations and particles as discrete entities in a Lagrangian approach. The gas phase solver is used to study the generation of shock waves and the high temperature plasma kernel. A one-way coupling approach between the two phases is used and various Lagrangian sub-models are developed to study the particle phase evolution in the system. Comparison with shock tube measurements where a planar shock wave perpendicular to the shock tube wall interacts with particles residing on the wall showed that the predominant mechanism of particle lifting is the Saffman force generated on particles due to velocity gradients in the gas boundary layer. A second configuration with an overhead spherical blast wave generated by an electrostatic discharge (ESD) interacting with a polydisperse distribution of spherical particles placed at three wall-electrode distances was considered. The predicted particle lifting heights and velocities are found to compare well with measurements in an ESD configuration initiated by the dielectric breakdown of ambient air.