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In this work we numerically demonstrate both significant transient (i.e. non-modal) linear amplification and sustained nonlinear turbulence in a kinetic plasma system with no unstable eigenmodes. The particular system considered is an…

Plasma Physics · Physics 2015-07-22 Matt Landreman , Gabriel G. Plunk , William Dorland

For delayed reaction-diffusion Schnakenberg systems with Neumann boundary conditions, critical conditions for Turing instability are derived, which are necessary and sufficient. And existence conditions for Turing, Hopf and Turing-Hopf…

Dynamical Systems · Mathematics 2020-01-08 Weihua Jiang , Hongbin Wang , Xun Cao

A specific set of dimensionless plasma and turbulence parameters is introduced to characterize the nature of turbulence and its dissipation in weakly collisional space and astrophysical plasmas. Key considerations are discussed for the…

Solar and Stellar Astrophysics · Physics 2024-04-18 Gregory G. Howes

Sawtooth oscillations can trigger off heat and turbulence pulses that propagate into the edge plasma, and thus enhancing the edge shear flow and inducing a transition from low confinement mode to high confinement mode. The influences of…

We are interested in the threshold phenomena for propagation in nonlocal diffusion equations with some compactly supported initial data. In the so-called bistable and ignition cases, we provide the first quantitative estimates for such…

Analysis of PDEs · Mathematics 2022-01-06 Matthieu Alfaro , Arnaud Ducrot , Hao Kang

Hydraulic jumps are oftentimes encountered in natural and human-made environments. The transition from supercritical to subcritical flow involves large energy dissipation rates and substantial air entrainment, preventing the use of…

Fluid Dynamics · Physics 2022-04-26 Matthias Kramer , Daniel Valero

Strongly driven ion-scale turbulence in tokamak plasmas is shown to be regulated by a new propagating zonal flow mode, the toroidal secondary mode, which is nonlinearly supported by the turbulence. The mode grows and propagates due to the…

Plasma Physics · Physics 2026-03-24 Richard Nies , Felix Parra , Michael Barnes , Noah Mandell , William Dorland

The Turing instability is a paradigmatic route to patterns formation in reaction-diffusion systems. Following a diffusion-driven instability, homogeneous fixed points can become unstable when subject to external perturbation. As a…

Pattern Formation and Solitons · Physics 2015-09-02 Joseph D. Challenger , Raffaella Burioni , Duccio Fanelli

To understand the earliest stages of planet formation, it is crucial to be able to predict the rate and the outcome of dust grains collisions, be it sticking and growth, bouncing, or fragmentation. The outcome of such collisions depends on…

Earth and Planetary Astrophysics · Physics 2015-06-05 Alexander Hubbard

The instability of a monoenergetic electron beam in a collisional one-dimensional plasma bounded between grounded walls is considered both analytically and numerically. Collisions between electrons and neutrals are accounted for the plasma…

Plasma Physics · Physics 2017-01-04 Dmytro Sydorenko , Igor D. Kaganovich , Peter L. G. Vetzek

We consider the evolution of a family of 2D dispersive turbulence models. The members of this family involve the nonlinear advection of a dynamically active scalar field, the locality of the streamfunction-scalar relation is denoted by…

Fluid Dynamics · Physics 2009-02-20 Jai Sukhatme , Leslie M. Smith

It is not fully understood how electromagnetic waves propagate through plasma density fluctuations when the size of the fluctuations is comparable with the wavelength of the incident radiation. In this paper, the perturbing effect of a…

Plasma Physics · Physics 2016-09-21 Alf Köhn , Eberhard Holzhauer , Jarrod Leddy , Matthew B Thomas , Roddy G L Vann

In this note, we propose a new idea by analyzing the basic disturbance equations, and give starting equations for understanding the instability phenomena of laminar flows and transition to turbulence. It is considered that there is an…

Fluid Dynamics · Physics 2007-05-23 Hua-Shu Dou

The thin-shell instability has been named as one process, which can generate entangled structures in astrophysical plasma on collisional (fluid) scales. It is driven by a spatially varying imbalance between the ram pressure of the inflowing…

High Energy Astrophysical Phenomena · Physics 2015-09-30 M. E. Dieckmann , H. Ahmed , D. Doria , G. Sarri , R. Walder , D. Folini , A. Bret , A. Ynnerman , M. Borghesi

The present study addresses the reaction zone structure and burning mechanism of unstable detonations. Experiments investigated mainly two-dimensional methane-oxygen cellular detonations in a thin channel geometry. The sufficiently high…

Solar wind is probably the best laboratory to study turbulence in astrophysical plasmas. In addition to the presence of magnetic field, the differences with neutral fluid isotropic turbulence are: weakness of collisional dissipation and…

Solar and Stellar Astrophysics · Physics 2015-06-16 Olga Alexandrova , Christopher H. K. Chen , Luca Sorriso-Valvo , Timothy S. Horbury , Stuart D. Bale

In the full-orbit particle simulations of energetic particle transport in plasmas, the plasma turbulence is typically described as a homogeneous superposition of linear Fourier modes. The turbulence evolution is, however, typically a…

Solar and Stellar Astrophysics · Physics 2012-04-03 Timo Laitinen , Silvia Dalla , James Kelly

Subcritical transition to turbulence, in which the laminar state is linearly stable yet finite-amplitude perturbations develop into turbulence, is ubiquitous but lacks a simple analytical framework. We demonstrate such a framework using a…

Fluid Dynamics · Physics 2026-03-27 Yoshiki Hiruta

This article is devoted to Feller's diffusion equation which arises naturally in probabilities and physics (e.g. wave turbulence theory). If discretized naively, this equation may represent serious numerical difficulties since the diffusion…

Analysis of PDEs · Mathematics 2020-05-26 Denys Dutykh

We investigate how wave propagation is modified by the presence of heat sources and sinks, in the simple 1D, hydrodynamical case, including chromosphere and solar wind. We integrate the time-dependent hydrodynamic equations of the solar…

Astrophysics · Physics 2007-10-05 R. Grappin , J. Léorat , R. Pinto , Y. -M. Wang