Charged Particle-Laden Turbulence: The Hidden Architect of Lightning Discharges

From lightning flashes in electrified clouds to tribocharged dust particles in sandstorms, turbulent flows laden with charged particles are prevalent in a wide range of natural phenomena and industrial applications. In these systems, polydispersed particles often carry electric charges that correlate with particle size. As inertial particles preferentially cluster in specific regions of turbulence, the associated charge segregation leads to multiscale electric fields that remain poorly understood. In this talk, we present direct numerical simulations of bisidpersed, oppositely charged particles in homogeneous isotropic turbulence to investigate this interesting problem. Our simulations show that the resulting electric fields are highly intermittent, with a significant probability of extreme local field intensities that could trigger electric breakdown. A scaling analysis is then proposed to relate the intensity of such extreme electric fields to particle characteristics and turbulence properties. To explore the implications for lightning phenomena, fractal lightning modeling is further performed, which predicts the realistic propagation of lightning discharges in the turbulence-induced electric fields. Finally, the geometric features and the released energy of lightning discharges are discussed, revealing that both are strongly influenced by underlying turbulent coherent structures. These findings highlight a fundamental connection between the initiation and propagation of lightning discharges and particle-turbulence interactions.