Large-eddy simulation of charged particle flows to model sandstorms

Intense electric fields and lightning have been observed in sandstorms. It is proposed to investigate the physical mechanisms essential for production and sustenance of large-scale electric fields in sandstorms. Our central hypothesis is that the turbulent transport of charged sand particles is a necessary condition to attain sustained large-scale electric fields in sandstorms. Our investigation relies on simulating turbulent two-phase (~air and suspended sand particles) flows in which the flow of air is governed by the filtered Navier-Stokes equations with a subgrid-scale model in a Large-Eddy-Simulation setting, while dust particles are modeled using the Eulerian approach using a version of the Direct Quadrature Method of Moments. For the fluid phase, the LES of incompressible turbulent boundary layer employs stretched spiral vortex subgrid-scale model and a virtual wall model similar to the work of Cheng, Pullin \& Samtaney (J. Fluid Mech. 2015). We will quantify the effects of different sand particle distributions, and turbulent intensities on the root-mean-square of the generated electric fields.