Particle resuspension by a periodically forced impinging jet

摘要: When hovering over sandy terrain, the rotor of helicopters generates a downward jet that induces resuspension dust and debris. We investigate mechanisms govern particle in such flow using an Eulerian–Lagrangian approach based on large-eddy simulation turbulence. The wake generated by helicopter is modelled as vertical impinging jet, to which sequence periodically forced azimuthal vortices superposed. resulting field provides unique range scales with particles can interact. Downstream impingement region, layers negative vorticity (secondary vortices) form upwash side primary (large-scale) vortices. These then detach from surface together near-wall (small-scale) populating wall-jet region. show how dynamics sediments governed its interaction these structures. After initial lift off surface, accumulate regions where roll around vortex, forming rib-like structures either propel away vortex or entrap them shear layer between secondary demonstrate trapped are more likely reach outer region generate persistent cloud airborne particles. also that, time-averaged sense, deposition fluxes balance each other near surface.