相关论文: Conservation of writhe helicity under anti-paralle…

The conjecture that helicity (or knottedness) is a fundamental conserved quantity has a rich history in fluid mechanics, but the nature of this conservation in the presence of dissipation has proven difficult to resolve. Making use of…

Here we show that under quantum reconnection, simulated by using the three-dimensional Gross- Pitaevskii equation, self-helicity of a system of two interacting vortex rings remains conserved. By resolving the fine structure of the vortex…

Helicity is a topological invariant that measures the linkage and knottedness of lines, tubes and ribbons. As such, it has found myriads of applications in astrophysics and solar physics, in fluid dynamics, in atmospheric sciences, and in…

This paper addresses the interaction of initially anti-parallel vortex tubes containing an axial flow that induces a twisting of the vortex lines around the tube axes, using numerical simulations. Vortex tube configurations with both the…

Helicity, a measure of the linkage of flux lines, has subtle and largely unknown effects upon dynamics. Both magnetic and hydrodynamic helicity are conserved for ideal systems and could suppress nonlinear dynamics. What actually happens is…

We consider the reconnection of two untwisted, linked quantised vortex rings in a Bose-Einstein condensate. We show that the reconnection is capable of transferring helicity, from the links present in the initial configuration, to a…

Starting from the continuum definition of helicity, we derive from first principles its different contributions for superfluid vortices. Our analysis shows that an internal twist contribution emerges naturally from the mathematical…

When two vortices cross, each of them breaks into two parts and exchanges part of itself for part of the other. This process, called vortex reconnection, occurs in classical as well as superfluids, and in magnetized plasmas and…

We present a new model of magnetic reconnection in the presence of turbulence, applicable when the magnetic helicity is non-zero. The new model differs from the Lazarian-Vishniac turbulent reconnection theory by emphasizing the role of…

We discuss some aspects of magnetic reconnection which could help in understanding many aspects of magnetic plasma interactions. We will show that the helical structure often observed in polar jets is a natural consequence of magnetic…

In addition to mass, energy, and momentum, classical dissipationless flows conserve helicity, a measure of the topology of the flow. Helicity has far-reaching consequences for classical flows from Newtonian fluids to plasmas. Since…

Kinetic helicity is one of the invariants of the Euler equations that is associated with the topology of vortex lines within the fluid. In superfluids, the vorticity is concentrated along vortex filaments. In this setting, helicity would be…

Helicity is a fundamental property of magnetic fields, conserved in ideal MHD. In flux rope topology, it consists of twist and writhe helicity. Despite the common occurrence of helical structures in the solar atmosphere, little is known…

The simplest case is the reconnection of a pair of antiparallel line vortices, e.g., condensation trails of an aircraft. The vortices first undergo long wave deformation (Crow waves), and then reconnect to form coherent structures. Although…

Fully developed homogeneous isotropic turbulence in 2D is fundamentally different from 3D. In 2D, the simultaneous conservation of both energy and enstrophy in the inertial ranges of scales leads to a forward cascade of enstrophy and a…

The twist and writhe numbers and magnetic energy of an orthogonally perturbed vortex filaments are obtained from the computation of the magnetic helicity of geodesic and abnormal magnetohydrodynamical (MHD) vortex filament solutions. Twist…

The evolution and self-reconnection of a perturbed trefoil vortex knot is simulated, then compared to recent experimental measurements (Scheeler et al. 2014a). Qualitative comparisons using three-dimensional vorticity isosurfaces and lines,…

Three-dimensional images of evolving numerical trefoil vortex knots are used to study the growth and decay of the enstrophy and helicity. Negative helicity density ($h<0$) plays several roles. First, sheets of oppositely-signed helicity…

A relativistic helicity has been formulated in the four-dimensional Minkowski space-time. Whereas the relativistic distortion of space-time violates the conservation of the conventional helicity, the newly defined relativistic helicity…

The discrete nature of the solar magnetic field as it emerges into the corona through the photosphere indicates that it exists as isolated flux tubes in the convection zone, and will remain as discrete flux tubes in the corona until it…