Related papers: Vortex annihilation and inverse cascades in two di…
We perform a numerical analysis of superfluid turbulence produced by thermal counterflow in He II by using the vortex filament model. Counterflow in a low aspect ratio channel is known to show the transition from laminar flow to the two…
Fully developed turbulence is analised with the lattice model employing vortex tube representation which is introduced recently by the authors. Several characteric features observed in experiments and direct numeric integrations are…
To answer the question whether a cascade of energy exists or not in turbulence, we propose a set of correlation functions able to test if there is an irreversible transfert of energy, step by step, from large to small structures. These…
We discuss structure and geometrical characteristics of coherent vortices appearing as a result of the inverse cascade in the two-dimensional turbulence in a finite box. We demonstrate that the universal velocity profile, established…
In fluid turbulence, energy is transferred from a scale to another by an energy cascade that depends only on the energy dissipation rate. It leads by dimensional arguments to the Kolmogorov 1941 (K41) spectrum. Remarkably the normal modes…
We look at various correlation functions, which include those that involve both the velocity and the vorticity fields, in two-dimensional (2D) isotropic homogeneous unforced turbulence. We adopt the more intuitive approach due to Kolmogorov…
We derive a type of kinetic equation for Kelvin waves on quantized vortex filaments with random large-scale curvature, that describes step-by-step (local) energy cascade over scales caused by 4-wave interactions. Resulting new energy…
Turbulent drag of an oscillating microsphere, that is levitating in superfluid $^4$He at mK temperatures, is unstable slightly above a critical velocity amplitude $v_c$. The lifetime $\tau$ of the turbulent state is determined by the number…
Turbulence, produced by an impulsive spin-down from angular velocity Omega to rest of a cube-shaped container, is investigated in superfluid 4He at temperatures 0.08 K - 1.6 K. The density of quantized vortex lines L is measured by…
The currents and field distributions of a vortex in a thin superconducting strip of a width $W$ is considered. It is shown that unlike infinite films where the vortex field crosses the film only in one direction (say, from the half-space…
Vorticity in two-dimensional superfluids is subject to intense research efforts due to its role in quantum turbulence, dissipation and the BKT phase transition. Interaction of sound and vortices is of broad importance in Bose-Einstein…
We investigate the process of formation of large-scale structures in a turbulent flow confined in a thin layer. By means of direct numerical simulations of the Navier-Stokes equations, forced at an intermediate scale, we obtain a split of…
In this paper, the scaling property of the inverse energy cascade and forward enstrophy cascade of the vorticity filed $\omega(x,y)$ in two-dimensional (2D) turbulence is analyzed. This is accomplished by applying a Hilbert-based technique,…
The experimental investigation of superfluid turbulence in 3He-B is generally not possible with the techniques which have been developed for 4He-II. We describe a new method by which a transient burst of turbulent vortex expansion can be…
In this work, we provide two novel approaches to show that incompressible fluid flow in a finite domain contains at most a finite number vortices. We use a recently developed geometric theory of incompressible viscous flows along with an…
In this paper we consider a recent theoretical prediction (Bragg \emph{et al.}, Phys. Fluids \textbf{28}, 013305 (2016)) that for inertial particles in 2D turbulence, the nature of the irreversibility of the particle-pair dispersion inverts…
We report on the extension of the experiments (P. M. Walmsley et al., Phys. Rev. Lett. 99, 265302 (2007)) on the decay of quasiclassical turbulence generated by an impulsive spin-down from angular velocity Omega to rest of superfluid 4He in…
We study structure formation in two-dimensional turbulence driven by an external force, interpolating between linear instability forcing and random stirring, subject to nonlinear damping. Using extensive direct numerical simulations, we…
This paper develops a simple model of the inertial range of turbulent flow, based on a cascade of vortical filaments. A binary branching structure is proposed, involving the splitting of filaments at each step into pairs of daughter…
We report a numerical study, supplemented by phenomenological explanations, of ``energy condensation'' in forced 2D turbulence in a biperiodic box. Condensation is a finite size effect which occurs after the standard inverse cascade reaches…