A physical model of turbulence cascade via vortex reconnection sequence and avalanche

Direct numerical and large-eddy simulation of trefoil knotted vortices

“…Overall, there are similarities between the reconnection dynamics of topologically complex thin-core vortex knots and of a symmetric parallel reconnection as discussed by previous works, such as Hussain & Duraisamy (2011), Van Rees et al. (2012) and Yao & Hussain (2020 b ), etc. An asymmetric knot configuration, however, results in much more complex fine-scale vortex structures and non-trivial global helicity dynamics.…”

“…cascaded reconnection), which results in small-scale vorticity surrounding the thread on the top. The structure of the small-scale vortices generated by this reconnection is similar to the cascaded bridgelet structure discussed by Yao & Hussain (2020 b ) (C-structure in figure 7( e ) of the cited paper), in which the mechanism of the cascade reconnection has been outlined for the case. The difference with the current work is that the strain field in the current paper is asymmetric, resulting in a more asymmetric evolution of the bridgelets (as shown on the lower right of figure 13).…”

“…Van Rees, Hussain & Koumoutsakos (2012) performed simulations up to and revealed the dynamics of first and second reconnection of anti-parallel vortices, with and without imposed axial flow. In the latest work (Yao & Hussain 2020 b ), with a similar anti-parallel configuration, the Reynolds number range has been extended up to 40 000. These simulations are all focused on a simple vorticity set-up (i.e.…”

Matching theory to characterize sound emission during vortex reconnection in quantum fluids

“…Viscosity is responsible for the diffusion of the vorticity field: an initially finite-supported, or very intense, vorticity tube will gradually loose its distinctiveness in time. Moreover, even for reconnecting processes where the vorticity field of the tubes is so intense that the reconnection time-scale is much faster than viscous diffusion, a variety of new vortex patches like bridges [4,9], ribbons [10], pancakes [11], or extra vortex tubes [12,13] emerge. Hence, the presence of viscosity is two-folded when studying classical vortex reconnections.…”

Suppressing thermalization and constructing weak solutions in truncated inviscid equations of hydrodynamics: Lessons from the Burgers equation

“…Given the potential usefulness of our approach to revisit the analyticity-strip method to numerically investigate the question of blow-up of the Euler equation, it might be useful to comment on recent studies of this problem. In brief, although there is some evidence that the Euler equations could avoid singularities through the formation of vortex sheets [26][27][28], other results [29][30][31] suggests that this question is far from settled. Therefore, our work, although demonstrated here for the Burgers equation, could play a role in revisiting this issue from the point of view of the width of the analyticity strip.…”