Large-Eddy Simulation of Wake Vortex Evolution from Roll-Up to Decay

Abstract

The development of an aircraft wake vortex from the roll-up until vortex decay is studied. An aircraft model and the surrounding flow field obtained from high-fidelity Reynolds-averaged Navier-Stokes simulation are swept through a ground-fixed computational domain to initialize the wake. After the wake initialization, the large-eddy simulation of the vortical wake is performed until vortex decay. The methodology is tested with the NACA0012 wing and applied to the DLR-F6 wing-body model. The roll-up process of the vorticity sheet from a main wing and the merge of an inboard wing vortex into the wingtip vortex are simulated. Vortex parameters such as the averaged circulation, vortex core radius and vortex separation are also evaluated. The growth rate of the vortex core radius is relatively small during the roll-up where the fine mesh resolution in the LES is required to capture the tiny vortex core in the RANS simulation. A high-lift configuration of a landing large transport aircraft was also studied where the wingtip vortices merge with the co-rotating and stronger outboard flap vortices.