Large eddy simulation of electrostatic effect on particle transport in particle-laden turbulent pipe flows

Electrostatic effect on particle transport in particle-laden turbulent pipe flows at Re-b = 44000 was investigated by coupling LES with Lagrange particle tracking technology. The particle governing equation included drag force, lift force and electrostatic force. Triboelectrification and collision electrification were basically considered for particle charging ways in the particle-laden turbulent pipe flows. In this work, three particle St numbers (3.9, 35.6, 142.2) were considered to compare the electrostatic effect on particle behavior. It was found that in the near-wall region, electrostatics destroyed particle aggregation around the vortex structure. Particle-ejection delay effect and particle-sweep premature effect were then proposed in boundary layer due to electrostatics. Electrostatics affected particle distribution and that became more significant with electrostatics increasing. Electrostatics prevented particles from ejecting as particle-ejection delay effect and accelerated particle moving and caused premature occurrence of particle sweep as particle-sweep premature effect. Charged particles were observed to distribute in the low-speed streaks, high-speed streaks, and the region between them, which was caused by particle-ejection delay and particle-sweep premature. It can be concluded that in the turbulent pipe flows electrostatic effect destroyed particle normal distribution under single turbulence effect.