Numerical Simulation of a 65-Degree Delta-Wing Flowfield

Computations of the e ow over a 65-deg delta wing at an angle of attack of 30 deg and roll angles of 0 and 24 deg are presented. The unsteady, three-dimensional full Navier› Stokes equations are solved using a Beam› Warming implicit algorithm. The use of both block tridiagonal and diagonal inversion schemes with subiterations has been investigated. The effects of time-step size and grid resolution are also discussed. Computational results are compared with high-resolution particle image velocimetry measurements. Analysis of the structure of the vortex breakdown for the 24-deg roll case shows predominantly spiral-type breakdown occurring. Bubble-type breakdown is observed for short periods during transient upstream movements of the breakdown location. A distinguishing characteristic of the bubble breakdown is the existence of a three-dimensional stagnation point at the head of the breakdown region. The existence of this stagnation point provides the distinctive change in appearance between bubble and spiral breakdown.