Electrification in aeolian sand transport and the associated electric fields

Near-surface saltating sand flow is a typical example of high-Reynolds-number wall turbulence, accompanied by particle charging and strong wind-blown sand electric fields. Existing numerical simulations mostly rely on Reynolds-averaged flow fields and point-charge Coulomb-based electric field modeling, which cannot reproduce the flow and electric field fluctuations observed in reality. In this study, we numerically simulate the wind-sand-electric multiphysics coupled saltating sand flow using large-eddy simulation, a Lagrangian point-particle model, and the Particle-Particle-Particle-Mesh electric field solver. The results reveal that the vertical electric field decays monotonically with height, reaching up to 50 kV/m near the wall. The fluctuation of the vertical electric field also decays with height, with near-wall fluctuations reaching about half of the mean value. Although the mean streamwise and spanwise electric fields are zero, their fluctuations near the wall can reach 1/10–1/20 of the vertical electric field fluctuations. Strong electric-particle interactions reduce the mean sand transport rate and the characteristic scale of strongly correlated particle concentration structures. Furthermore, particle aggregation leads to coherent structures in the electric field, and the energy spectra of the streamwise and spanwise electric fields exhibit a −5/3 scaling region.