Large-eddy simulation of interface instability of low-density fluids

The subgrid-scale (SGS) turbulence transport terms were modeled by using the stretched-vortex SGS stress model and a large-eddy simulation (LES) code MVFT was developed to investigate the multi-viscous-flow and turbulence problems. Then the interface instability and its induced turbulent mixing of the low-density fluids were simulated numerically by the MVFT code. The simulated images were compared with the experimental results and the detailed analyses were carried out in the following aspects: the development of the perturbed interfaces, the propagations of the shock waves in the flow field and their interactions, the evolutions of the turbulent mixing zone edges, and the instantaneous density and turbulent kinetic energy of the flow filed. Comparisons show that the obtained numerical images for the interface evolutions and the wave structures in the flow field are consistent with the experimental results. And the three-dimensionally simulated results are in agreement with the two-dimensionally simulated ones, which including the positions of the perturbed interfaces, the waves and the turbulent mixing zone edges. Only the two-dimensional simulated images for the the configurations of the perturbed interfaces in the later stage are different from the three-dimensionally simulated results. At the same time, the numerical simulations explain that the turbulent flows have strong threedimensional effects.