Formation of a Dense Flux Rope by a Siphon Flow

Williams, Thomas; Taroyan, Y.

doi:10.3847/1538-4357/aa9d95

Cited by 11 publications

(9 citation statements)

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“…The source term on the right hand side of the energy equation 7represents a coupling of twists and inflow along the thread, and the equation remains valid in the non-linear regime as shown by Williams & Taroyan (2018). The analysis of twist amplification cannot be performed using standard normal mode methods.…”

Section: Torsional Perturbationsmentioning

confidence: 99%

Amplification of magnetic field twisting by a stagnation point flow

Sumner

Taroyan

2020

A&A

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Context. Flows are a common feature of many processes occurring in the solar atmosphere, such as the formation of prominences where evaporated plasma from the chromosphere condensates along thin prominence threads that are seen to twist and oscillate. Aim. We aim to investigate the twisting of these threads by plasma condensation during their formation. Methods. We introduce a simple model with fixed critical points where the flow speed matches the Alfvén speed. This allows us to study the problem separately in the sub-Alfvénic and super-Alfvénic regimes. The temporal and spatial evolution of small amplitude initial twists along a thread is investigated analytically and numerically. Results. Analytical solutions are constructed in terms of the generalised hypergeometric functions. The solutions grow in time, despite the absence of any influxes of energy or magnetic fields. These results are confirmed numerically: We find oscillations with an amplifying amplitude and increasing period in the sub-Alfvénic regime. In the super-Alfvénic regime, we find twist amplification without any accompanying oscillations. An interesting result is the convergence of the twists at the critical points that leads to the formation of steep gradients and small scales. Energy is transferred from the flow to the amplifying twists. Conclusions. Magnetic field lines may be twisted by a stagnation point flow without the influx of any azimuthal field or energy. This twisting could assist in the formation of topology that is able to support the growth of prominences. The formation of steep gradients and small scales at the critical point is a new phenomenon which requires further investigation in the non-linear regime with the inclusion of magnetic diffusion.

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Section: Torsional Perturbationsmentioning

confidence: 99%

Amplification of magnetic field twisting by a stagnation point flow

Sumner

Taroyan

2020

A&A

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“…We note that the energy Eq. (6) remains valid in the non-linear regime (Williams & Taroyan 2018). The analysis of twist amplification cannot be reduced to standard stability analysis which involves setting the linear perturbations proportional to exp(−iωt) and solving the resulting eigenvalue problem for the complex frequency ω.…”

Section: Torsional Perturbationsmentioning

confidence: 99%

“…The mechanism of twist amplification has been studied in the linear regime in the context of upflows (Taroyan 2015) and intergranular downdrafts . The back reaction of the amplified twists on the mass flows and their non-linear evolution has been studied by Williams et al (2016), Williams & Taroyan (2018).…”

Section: Introductionmentioning

confidence: 99%

Triggering of twists in solar prominence threads

Taroyan

Soler

2019

A&A

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Context. Magnetic twists are commonly associated with solar prominences. Twists are believed to play an important role in supporting the dense plasma against gravity as well as in prominence eruptions and coronal mass ejections, which may have a severe impact on the Earth and its near environment. Aims. We used a simple model to mimic the formation of a prominence thread by plasma condensation with the aim of investigating the possibility of triggering twists during this process. Methods. Temporal and spatial evolution of torsional Alfvénic perturbations driven by random photospheric motions was analysed using the linearised governing equations of motion and induction. Results. We find that small amplitude perturbations are exponentially amplified in time as they propagate along the condensing thread. Mechanisms contributing to the rapid growth are explored. The result of the amplification process is the generation of large amplitude axisymmetric twists along the thread. Conclusions. Magnetic twists may be triggered along a prominence thread when it is permeated by a converging flow, for example, during the evaporation and condensation of plasma along the thread. This may lead to the generation of vortices in the non-linear regime.

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“…The nodes with more materials will automatically supplement those with fewer materials. This automatic adjustment bears resemblance to the siphonic effect [31], which is the result of height difference between liquid surfaces. Pascal's law p = ρg h applies to the siphonic process, in which the effect of atmospheric pressure can be expressed as P-ρg h. Here, the automatic balancing of materials in the supply chain is analogized as a virtual siphon:…”

Section: Solution Of Endpoint Valuementioning

confidence: 84%

Optimal Logistics Control of an Omnichannel Supply Chain

et al. 2019

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This paper aims to find the best way to control logistics in an omnichannel supply chain (OSC). For this purpose, two steps of work were carried out around case-based reasoning (CBR). In the first step, the combined feedback which proved stability was selected to control logistics in the single node, while the variational method and the virtual siphon were combined to determine the optimal control curve. There is a linear part and a nonlinear part in the combined feedback. The new method of storing data mode is “data turning to picture”. In the second step, image features were extracted by the hybrid method of SURF-GoogLeNet and used for case matching via the grey cloud method. SURF-GoogLeNet was firstly used to update the weight proportion of the defect points in the whole image via the speeded up robust features (SURF) method and secondly to self-extract features using the GoogLeNet method. Finally, the effectiveness of the proposed methods was verified through experiments. The research findings shed new light on the management of supply chains.

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Formation of a Dense Flux Rope by a Siphon Flow

Cited by 11 publications

References 50 publications

Amplification of magnetic field twisting by a stagnation point flow

Amplification of magnetic field twisting by a stagnation point flow

Triggering of twists in solar prominence threads

Optimal Logistics Control of an Omnichannel Supply Chain

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