Helicity and dissipation in trefoil vortex knots

The evolution of new and old trefoil vortex knots is followed using color coded vorticity isosurfaces and quantitative analysis of the production, transport and dis- sipation terms along the centerline vortex loops. Cases include initially three-fold symmetric trefoil vortex knots plus extensions of the previous strongly perturbed trefoils. The extensions at later times, and at higher Reynolds numbers, demon- strate that -5/3 energy spectra can develop along with convergence of persistent large values of the dissipation rates ε. The centerline vortex and spectral analysis demonstrates several roles for the helicity. First, when the initial state is too sym- metric, helicity contributes to suppressing turbulent growth. In contrast, with a strong perturbation and very large computation volumes, the transport of helicity promotes the formation of turbulent dissipation.