Some Effects of Momentum Diffusion on Axisymmetric Vortices

Abstract

In the absence of momentum diffusion (viscous or turbulent) in a steady state axially bounded vortex, such as that produced by a Ward-type tornado simulator, a two-celled vortex configuration in which the inner cell is entirely stagnant is to be expected. Therefore, diffusion is directly responsible or at least highly influential in producing other vortex phenomena, including a single-cell structure, a vortex breakdown, a central downdraft, and a subhydrostatic central surface pressure. The means by which these are brought about by diffusion are discussed in the context of the tornado simulator. Some of the given arguments are extended in a more speculative manner to atmospheric vortices.