The persistence of trailing vortices: A modeling study

The principal subject of this paper is analysis and modeling of turbulent wing tip vortex flows in a far‐field region of the vortex evolution. The choice of a Reynolds stress closure (RSC) to model the vortex turbulence is shown to be indispensable for representation of the flow rotation effects on turbulence. The principal result reported is the model–experiment comparison of the vortex growth rates for different vortex Reynolds numbers. The mean vortical flow generated by the wing tip very effectively suppresses the Reynolds shear stress, which mediates the extraction of energy from the mean flow by turbulence. In consequence, the vortex‐core growth rate is controlled only by molecular viscosity and the vortex turbulence decays since the turbulence production rate is very nearly zero. This rather unexpected result is shown to be supported by experiments. Finally, it is shown that the computed turbulence structure is consistent with experimental data at the NASA Ames Research Center.

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