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When vortex rings collide head-on at high enough Reynolds numbers, they ultimately annihilate through a violent interaction which breaks down their cores into a turbulent cloud. We experimentally show that this very strong interaction,…

We study the time evolution of an incompressible fluid with axial symmetry without swirl, assuming initial data such that the initial vorticity is very concentrated inside $N$ small disjoint rings of thickness $\varepsilon$ and vorticity…

Analysis of PDEs · Mathematics 2022-03-11 Paolo Buttà , Guido Cavallaro , Carlo Marchioro

Vortex rings have the ability to transport fluid over long distances. They are usually produced by ejecting a volume of fluid through a circular orifice or nozzle. When the volume and velocity of the ejected fluid are known, the vortex'…

Fluid Dynamics · Physics 2021-07-20 Guillaume de Guyon , Karen Mulleners

Motivated by the recent observation that exponentially long coherence times can be achieved for edge spins in models with strong zero modes, we study the impact of level crossings in finite-length spin chains on the dynamics of the edge…

Statistical Mechanics · Physics 2019-12-23 Ivo Maceira , Frédéric Mila

(abidged) Context: Stellar convection zones are characterized by vigorous high-Reynolds number turbulence at low Prandtl numbers. Aims: We study the dynamo and differential rotation regimes at varying levels of viscous, thermal, and…

Solar and Stellar Astrophysics · Physics 2017-02-22 P. J. Käpylä , M. J. Käpylä , N. Olspert , J. Warnecke , A. Brandenburg

In light of recent renewed interest in streaks in turbulent jets, the current work explores their coexistence with vortex rings in the near field of turbulent round jets. A Reynolds number, $Re=1.5 \times 10^5$ jet is studied at two…

Fluid Dynamics · Physics 2021-04-28 Jahnavi Kantharaju , Benjamin Leclaire , Laurent Jacquin

We present the results of a detailed set of one-zone models that account for the coupling between pulsation and convection following the original prescriptions of Stellingwerf (1986). Motivated by the arbitrary nature of the input…

Astrophysics · Physics 2009-11-10 A. Munteanu , G. Bono , J. Jose , E. Garcia-Berro , R. F. Stellingwerf

The onset of convection in the form of magneto-inertial waves in a rotating fluid sphere permeated by a constant axial electric current is studied through a perturbation analysis. Explicit expressions for the dependence of the Rayleigh…

Fluid Dynamics · Physics 2021-01-19 Radostin D. Simitev , Friedrich H. Busse

Pattern formation of a thin layer of vertically agitated wet granular matter is investigated experimentally. Due to the strong cohesion arising from the capillary bridges formed between adjacent particles, agitated wet granular matter…

Soft Condensed Matter · Physics 2013-01-24 Kai Huang Lorenz Butzhammer , Ingo Rehberg

When a droplet impacts a liquid film, a vortex ring form and govern momentum and species transport. We experimentally investigate vortex ring formation, propagation and instability during droplet impact onto liquid films, with particular…

Stably-stratified layers may be present at the top of the electrically-conducting fluid layers of many planets either because the temperature gradient is locally subadiabatic or because a stable composition gradient is maintained by the…

Earth and Planetary Astrophysics · Physics 2022-11-08 Celine Guervilly

We have used a model of magnetic accretion to investigate the accretion flows of magnetic cataclysmic variables. Numerical simulations demonstrate that four types of flow are possible: discs, streams, rings and propellers. The fundamental…

Astrophysics · Physics 2009-11-13 A. J. Norton , O. W. Butters , T. L. Parker , G. A. Wynn

We report experiments on thermally driven convection in an inclined layer of large aspect ratio in a fluid of Prandtl number $\sigma \approx 1$. We observed a number of new nonlinear, mostly spatio-temporally chaotic, states. At small…

patt-sol · Physics 2009-10-31 Karen E. Daniels , Eberhard Bodenschatz

The spatio-temporal dynamics of separation bubbles induced to form in a fully-developed turbulent boundary layer (with Reynolds number based on momentum thickness of the boundary layer of 490) over a flat plate are studied via direct…

Fluid Dynamics · Physics 2019-12-04 Wen Wu , Charles Meneveau , Rajat Mittal

The paper presents a numerical investigation of the leading-edge vortices generated by rotating triangular wings at Reynolds number $Re=250$. A series of three-dimensional numerical simulations have been carried out using a Fourier…

Fluid Dynamics · Physics 2015-04-20 Dmitry Kolomenskiy , Yossef Elimelech , Kai Schneider

The dynamics of convecting fluids in rotating spherical shells is governed at Prandtl numbers of the order unity by the interaction between differential rotation and roll-like convection eddies. While the differential rotation is driven by…

Fluid Dynamics · Physics 2009-05-25 F. H. Busse , R. D. Simitev

One prominent feature in the atmospheres of Jupiter and Saturn is the appearance of large-scale vortices. However, the sustaining mechanism of these large-scale vortices remains unclear. One possible mechanism is that these large-scale…

Fluid Dynamics · Physics 2021-09-30 Tao Cai

Gravitational instabilities play an important role in structure formation of gas-rich high-redshift disc galaxies. In this paper, we revisit the axisymmetric perturbation theory and the resulting growth of structure by taking the realistic…

Astrophysics of Galaxies · Physics 2015-02-04 Manuel Behrendt , Andreas Burkert , Marc Schartmann

Motivated by experiments performed in superfluid helium, we study numerically the motion of toroidal bundles of vortex filaments in an inviscid fluid. We find that the evolution of these large-scale vortex structures involves the…

Fluid Dynamics · Physics 2015-06-18 D. H. Wacks , A. W. Baggaley , C. F. Barenghi

We study the generation of large-scale vortices in rotating turbulent convection by means of Cartesian direct numerical simulations. We find that for sufficiently rapid rotation, cyclonic structures on a scale large in comparison to that of…

Solar and Stellar Astrophysics · Physics 2013-11-19 P. J. Käpylä , M. J. Mantere , T. Hackman