The stabilizing effects of axial stretching on turbulent vortex dynamics

The evolution and dynamics of vortices in inviscid, incompressible flow under the influence of a deformation field which causes stretching in the axial direction are studied. These vortices are simulated using three-dimensional vortex methods which offer the advantages of having no inherent numerical dissipation and great computational efficiency for short to intermediate times. Two cases in particular are studied: The evolution of a stable, but strongly perturbed vortex, and the evolution of an unstable vortex. In both types of vortices, it is found that the stretching and radial inflow associated with the surrounding deformation field can suppress the growth of disturbances and slow the development of turbulence. This stabilization is even greater than what one would expect from the purely kinematic effects of the deformation field alone, indicating there is a negative feedback on the nonlinear vortex dynamics. The physical mechanisms for stabilization by stretching are discussed, along with potential applications for understanding the stability of intense geophysical vortices maintained by convection.