An experimental investigation of mixing mechanisms in a shock-induced instability flow is described. We obtain quantitative two-dimensional maps the heavy-gas (SF 6 ) concentration using planar laser-induced fluorescence for case shock-accelerated cylinder heavy gas air. The instantaneous scalar dissipation rate, or χ, estimated experimentally first time this type flow, and used to identify regions most intense post-shock examine underlying mechanisms. observe growth certain beginning at...

A Mach 1.2 planar shock wave impulsively accelerates one of five different configurations heavy-gas (SF6) cylinders surrounded by lighter gas (air), producing or more pairs interacting vortex columns. The interaction the columns is investigated with laser-induced fluorescence in plane normal to axes cylinders. For first time, we experimentally measure early time stretching rate (in 220μs after before development secondary instabilities) material lines shock-accelerated gaseous flows...

The magnetohydrodynamics of active region NOAA 11283 is simulated using an initial non-force-free magnetic field extrapolated from its photospheric vector magnetogram. We focus on the reconnections at a null point that participated in X2.1 flare 2011 September 6 around 22:21 UT (SOL2011-09-06T22:21X2.1) followed by appearance circular ribbons and coronal dimmings. extrapolation displays three-dimensional (3D) topology overlying sheared arcade. Prior to flare, loops rise due Lorentz force,...

Abstract The magnetohydrodynamics of the solar corona is simulated numerically. simulation initialized with an extrapolated non-force-free magnetic field using vector magnetogram active region NOAA 12192, which was obtained from photosphere. Particularly, we focus on reconnections (MRs) occurring close to a null point that resulted in appearance circular chromospheric flare ribbons 2014 October 24 around 21:21 UT, after peak X3.1 flare. lines show presence three-dimensional (3D) near one...

In this paper, we present a magnetohydrodynamics simulation of NOAA active region 11166 to understand the origin confined X-class flare that peaked at 23:23 UT on 2011 March 9. The is initiated with magnetic field extrapolated from corresponding photospheric magnetogram using non-force-free-field extrapolation technique. Importantly, initial configuration identifies three-dimensional (3D) nulls and quasi-separatrix layers (QSLs), which nearly agree bright structures appeared in...

Abstract Magnetohydrodynamic simulation is carried out for the NOAA AR 12615 in time span t ∈ {05:48, 06:18} UT on 2016 December 5; covering events of a blowout jet and C1.2 flare. The are selected based small interval between their occurrences, which provides us with an opportunity to explore two energetically different magnetic reconnection (MR) within run single magnetohydrodynamic (MHD) simulation. initiated field extrapolated from vector magnetogram provided by Helioseismic Magnetic...

Measurements have been made of the growth by Richtmyer–Meshkov instability nominally single-scale perturbations on an air/sulfur hexafluoride (SF6) interface in a large shock tube. An approximately sinusoidal shape is given to wire mesh which supports polymeric membrane separating air from SF6. A single wave incident induces motion baroclinic mechanism vorticity generation. The visual thickness δ measured schlieren photographs obtained singly each run and high-speed pictures. Data are...

According to Parker's magnetostatic theorem, tangential discontinuities in magnetic field, or current sheets (CSs), are generally unavoidable an equilibrium magnetofluid with infinite electrical conductivity and complex topology. These CSs due a failure of field achieving force-balance everywhere preserving its topology while remaining spatially continuous state. A recent work [Kumar, Bhattacharyya, Smolarkiewicz, Phys. Plasmas 20, 112903 (2013)] demonstrated this CS formation utilizing...

The computations presented in this work aim to asses the importance of field line interlacing on spontaneous development current sheets. From Parker's magnetostatic theorem, such sheets is inevitable a topologically complex magnetofluid, with infinite electrical conductivity, at equilibrium. Relevant initial value problems are constructed by superposition two untwisted component fields, each being represented pair global magnetic flux surface. intensity then specified relative amplitude...

Parker's magnetostatic theorem extended to astrophysical magnetofluids with large magnetic Reynolds number supports ceaseless regeneration of current sheets and hence, spontaneous reconnections recurring in time. Consequently, a scenario is possible where the repeated provide an autonomous mechanism governing emergence coherent structures magnetofluids. In this work, such explored by performing numerical computations commensurate theorem. particular, explore evolution flux-rope governed...

Abstract The magnetic fields in the solar corona are generally neither force-free nor axisymmetric and have complex dynamics that difficult to characterize. Here we simulate topological evolution of coronal field lines (MFLs) using a magnetohydrodynamic model. simulation is initialized with non-axisymmetric non-force-free best correlates observed vector magnetograms active regions (ARs). To focus on these ideas, simulations performed for flaring AR 11283 noted its complexity well-documented...

Context. Erupting magnetic flux ropes (MFRs) are believed to play a crucial role in producing solar flares. However, the formation of erupting MFRs complex coronal configurations and their subsequent evolution flaring events not fully understood. Aims. We perform magnetohydrodynamic (MHD) simulation active region NOAA 12241 understand rising rope during onset an M6.9 flare on 2014 December 18 around 21:41 UT (SOL2014-12- 18T21:41M6.9), which was followed by appearance parallel ribbons....

The presented computations compare the strength of current sheets which develop near and away from magnetic nulls. To ensure spontaneous generation sheets, are performed congruently with Parker's magnetostatic theorem. simulations evince two dimensional three nulls as well them. An important finding this work is in demonstration comparative scaling peak density numerical resolution, for these different types sheets. results document to have larger while exhibiting a stronger than close or...

Richtmyer–Meshkov instability (RMI) has long been the subject of interest for analytical, numerical, and experimental studies. In comparing results experiment with numerics, it is important to understand limitations techniques inherent in chosen method(s) data acquisition. We discuss an where a laminar, gravity-driven column heavy gas injected into surrounding light accelerated by planar shock. A popular well-studied method flow visualization (using glycol droplet tracers) does not produce...

The performed magnetohydrodynamic simulations aim to assess the influence of chaotic magnetic field lines on spontaneous generation current sheets in an evolving viscous magnetofluid with infinite electrical conductivity. Suitable non-force-free initial fields having are constructed by superposing two Arnold-Beltrami-Childress fields. construction is such that superposed devoid any three or two-dimensional nulls, which potential sites sheet development. Consequently, notion spontaneity can...

Abstract Three-dimensional magnetic nulls relate to topology, and are propitious for triggering solar coronal transients. Although abundant in nature, their generation is not established. This paper reports magnetohydrodynamic simulations indicating the be dissipative self-organized structures. Categorically, results of two case studies presented. First, a potential null located at origin Cartesian coordinate system subjected sinusoidal flow. The seen bifurcate while conserving net...

The results of experiments on Richtmyer–Meshkov instability growth multimode initial perturbations an air–sulfur hexafluoride (SF6) interface in a conical geometry are presented. done relatively larger shock tube. A nominally planar is formed by sandwiching polymeric membrane between wire-mesh frames. single incident wave ruptures the resulting perturbations. develops from action baroclinically deposited vorticity at interface. visual thickness δ measured schlieren photographs obtained each...