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The idea that the knottedness (hydrodynamic Helicity) of a fluid flow is conserved has a long history in fluid mechanics. The quintessential example of a knotted flow is a knotted vortex filament, however, owing to experimental…

Fluid Dynamics · Physics 2015-06-17 Dustin Kleckner , Martin Scheeler , William T. M. Irvine

The dynamics of quantized vortices in rotating $^3$He-B is investigated in the low density (single-vortex) regime as a function of temperature. An abrupt transition is observed at $0.5 T_{\rm c}$. Above this temperature the number of vortex…

Soft Condensed Matter · Physics 2007-05-23 A. P. Finne , V. B. Eltsov , G. Eska , R. Hanninen , J. Kopu , M. Krusius , E. V. Thuneberg , M. Tsubota

We compare a recent study of the kinematics of optical filaments in three cooling flow clusters of galaxies with previous numerical simulations of jet-inflated hot bubbles, and conclude that the velocity structure functions of the filaments…

Astrophysics of Galaxies · Physics 2020-06-24 Shlomi Hillel , Noam Soker

A Wells turbine is an axial-flow turbine consisting of a rotor usually with symmetric (uncambered) blades staggered at a 90 degree angle relative to the incoming flow. This turbine is used within oscillating water column (OWC) systems,…

Fluid Dynamics · Physics 2018-08-22 Tiziano Ghisu , Francesco Cambuli , Pierpaolo Puddu , Irene Virdis , Mario Carta , Fabio Licheri

We develop a model and numerical method to study the large-amplitude flutter of rectangular membranes (of zero bending rigidity) that shed a trailing vortex-sheet wake in a three-dimensional (3D) inviscid fluid flow. We apply small initial…

Fluid Dynamics · Physics 2022-12-21 Christiana Mavroyiakoumou , Silas Alben

The source of the hummingbirds distinctive hum is not well understood, but there are clues to its origin in the acoustic nearfield and farfield. To unravel this mystery, we recorded the acoustic nearfield generated by six freely hovering…

A model for a new electron vortex beam production method is proposed and experimentally demonstrated. The technique calls on the controlled manipulation of the degrees of freedom of the lens aberrations to achieve a helical phase front.…

Optics · Physics 2014-02-10 L. Clark , A. Béché , G. Guzzinati , A. Lubk , M. Mazilu , R. Van Boxem , J. Verbeeck

We develop an analytical formalism to determine the statistical properties of a system consisting of an ensemble of vortices with random position in plane interacting with a turbulent field. We calculate the generating functional by…

Plasma Physics · Physics 2016-09-08 F. Spineanu , M. Vlad

A decomposition of the energy and helicity fluxes in a turbulent hydrodynamic flow is proposed. The decomposition is based on the projection of the flow to a helical basis that allows to investigate separately the role of interactions among…

Fluid Dynamics · Physics 2017-03-08 Alexandros Alexakis

In a numerical investigation, we demonstrate the existence and curious evolution of vortices in a ladder-type three-level nonlinear atomic vapor with linear, cubic, and quintic susceptibilities considered simultaneously with the dressing…

Pattern Formation and Solitons · Physics 2012-11-07 Yiqi Zhang , Zhenkun Wu , Chenzhi Yuan , Xin Yao , Keqing Lu , Milivoj Belić , Yanpeng Zhang

In confined rotating convection, a strong zonal flow can develop close to the side wall with a modal structure that precesses anti-cyclonically (counter to the applied rotation) along the side wall. It is surmised that this is a robust…

We have performed measurements and numerical simulations on a bundle of vortex lines which is expanding along a rotating column of initially vortex-free 3He-B. Expanding vortices form a propagating front: Within the front the superfluid is…

Soft Condensed Matter · Physics 2008-03-05 V. B. Eltsov , R. de Graaf , R. Hanninen , M. Krusius , R. E. Solntsev

We perform numerical simulation of quantum turbulence at zero temperature generated by an oscillating sphere. In this simulation, we injected vortices on the sphere to generate turbulence. Although we prepare injected vortex loops of…

Other Condensed Matter · Physics 2015-06-18 Ai Nakatsuji , Makoto Tsubota , Hideo Yano

The vortex ring is usually analytically modelled in computational studies involving vortex ring and shock wave interaction. However, incompressibility assumptions of the isolated vortex ring model mostly limits its applicability to the…

Fluid Dynamics · Physics 2024-10-31 Swapnil Ashok Ahire , Avijit Chatterjee

We investigate the dynamics and morphology of jets propagating into the interstellar medium using 2D relativistic hydrodynamic simulations. The calculations are performed assuming axisymmetric geometry and trace a long propagation of jets.…

Astrophysics · Physics 2009-11-10 Akira Mizuta , Shoichi Yamada , Hideaki Takabe

The buoyancy-driven motion of a deformable bubble rising near a vertical hydrophilic wall is studied numerically. We focus on moderately inertial regimes in which the bubble undergoes low-to-moderate deformations and would rise in a…

Fluid Dynamics · Physics 2025-01-16 Pengyu Shi , Jie Zhang , Jacques Magnaudet

The flow of quantized vortex lines in superfluid 3He-B is laminar at high temperatures, but below 0.6 Tc turbulence becomes possible, owing to the rapidly decreasing mutual friction damping. In the turbulent regime a vortex evolving in…

Soft Condensed Matter · Physics 2011-02-23 R. Hanninen , V. B. Eltsov , A. P. Finne , R. de Graaf , J. Kopu , M. Krusius , R. E. Solntsev

Vorticity plays a prominent role in the dynamics of incompressible viscous flows. In two-dimensional freely decaying turbulence, after a short transient period, evolution is essentially driven by interactions of viscous vortices, the…

Analysis of PDEs · Mathematics 2016-10-27 Thierry Gallay , Yasunori Maekawa

We present numerical simulations of simplified models for swimming organisms or robots, using chordwise flexible elastic plates. We focus on the tip vortices originating from three-dimensional effects due to the finite span of the plate.…

Fluid Dynamics · Physics 2018-03-21 T. Engels , D. Kolomenskiy , K. Schneider , J. Sesterhenn

In this contribution a numerical study of a turbulent jet flow is presented. The simulation results of two different variants of the Lattice Boltzmann method (LBM) are compared. The first is the well-established D3Q19 MRT model extended by…

Fluid Dynamics · Physics 2012-06-05 S. Geller , S. Uphoff , M. Krafczyk