COMPUTATION OF THE TIP VORTEX OFF A LOW-ASPECT-RATIO WING

The viscous transonic flow around a low-aspect-ratio wing has been computed using an implicit, three-dimensioinal, 'thin layer' Navier-Stokes solver. The grid around the geometry of interest is obtained numerically as a solution to a Dirichlet problem for the cube. The geometry chosen for this study is a low-aspect-ratio wing with large sweep, twist, taper, and camber. The topology chosen to wrap the mesh around the wing with good tip resolution is a C-O-type mesh. Using this grid, the flow around the wing was computed for a freestream Mach number of 0. 82 at an angle of attack of 5 deg. At this Mach number, an oblique shock forms on the upper surface of the wing, and a tip vortex and three-dimensional flow separation off the wing surface are observed. Particle path lines indicate that the three-dimensional flow separation on the wing surface is a part of the root of the tip-vortex formation. The lifting of the tip vortex before the wing trailing edge is clearly observed by following the trajectory of particles released around the wing tip. Refs.