Yinghe Qi

Abstract From the crewed Apollo missions to the recent Chinese Chang’e landings, the interaction between spacecraft exhaust plumes and lunar soil produces dusty clouds with high-speed particle ejection. Despite varying landing sites, remarkably stable streak patterns were observed, raising questions about their origin. We solved this puzzle by showing that these patterns were driven by Görtler instability from the curved compressed shear layer of the supersonic but surprisingly laminar jet.

Abstract Fluid elements deform in turbulence by stretching and folding. In this Letter, by projecting the material deformation tensor onto the largest stretching direction, we depict the dynamics of folding through the evolution of the material curvature.

Abstract Homogeneous and isotropic turbulence can be generated by many different mechanisms, from classical passive grids to jet arrays. By using high-speed jets, a jet array becomes a promising way to produce intense turbulence with large energy dissipation rates in water and wind tunnels. In this paper, a systematic experimental investigation was conducted to understand how the turbulence decay scales with the jet velocity, nozzle size, and nozzle spacings.