Mechanical engineering student Kristopher C. Pierson recently received third place recognition in the American Institute of Aeronautics and Astronautics (AIAA) Foundation Student Competition in the Masters Division. The award was presented for his presentation of Vorticity Confinement at the AIAA regional Midwest student conference held in Cleveland on April 5.
To improve accuracy of CFD simulations by combating numerical viscosity, the vorticity confinement (VC) approach was applied to tip vortices shed by stationary and rotating wings for the simulation of tip vortex evolution. The effect of numerical dissipation has shown to cause the vortex to spread and decay without the presence of physical dissipative terms; VC counteracts this effect and maintains the vortex strength. An investigation into Total variation Diminishing (TVD) limiters showed the minmod limiter to be the most stable but also the most dissipative. The limiters were first tested in 2D simulations, then evaluated in a 3D fixed wing case. To apply VC to viscous and turbulent flows, it is shown that for relevant parameters VC does not affect the physical rate of dissipation of line vortices for temporal and viscous scales relevant to wingtip vortices. VC was applied to the simulation of turbulent wingtip vortices with direct comparison to experiments. A helicopter rotating wing simulation was carried out to determine the effect of the addition of a winglet on VC parameters.
This research, led by Professor Povitsky, was sponsored by Air Force Research Laboratory (AFRL), Dayton Area Graduate School Institution (DAGSI) and Army Research Office (ARO). Present support is from NAVY SBIR and NSF-ICORP.