Shared memory parallelization for high-fidelity large-scale 3D polyhedral particle simulations

2021 ◽  
pp. 104008
Author(s):  
Eun Hyun Park ◽  
Volodymyr Kindratenko ◽  
Youssef M.A. Hashash
Keyword(s):  
Shared Memory ◽  
Large Scale ◽  
High Fidelity ◽  
Particle Simulations ◽  
Polyhedral Particle

Particle energization inside plasmoids: numerical and analytical investigations

2021 ◽  
Author(s):  
Xiaozhou Zhao ◽  
Rony Keppens ◽  
Fabio Bacchini
Keyword(s):  
Test Particle ◽  
Large Scale ◽  
Mass Density ◽  
Magnetic Islands ◽  
Chaotic Flow ◽  
Reynolds Decomposition ◽  
Particle Simulations ◽  
Particle Energization ◽  
Periodic Setting ◽  
A Current

<div> <div> <div> <p>In an idealized system where four magnetic islands interact in a two-dimensional periodic setting, we follow the detailed evolution of current sheets forming in between the islands, as a result of an enforced large-scale merging by magnetohydrodynamic (MHD) simulation. The large-scale island merging is triggered by a perturbation to the velocity field, which drives one pair of islands move towards each other while the other pair of islands are pushed away from one another. The "X"-point located in the midst of the four islands is locally unstable to the perturbation and collapses, producing a current sheet in between with enhanced current and mass density. Using grid-adaptive resistive magnetohydrodynamic (MHD) simulations, we establish that slow near-steady Sweet-Parker reconnection transits to a chaotic, multi-plasmoid fragmented state, when the Lundquist number exceeds about 3×10<sup>4</sup>, well in the range of previous studies on plasmoid instability. The extreme resolution employed in the MHD study shows significant magnetic island substructures. Turbulent and chaotic flow patters are also observed inside the islands. We set forth to explore how charged particles can be accelerated in embedded mini-islands within larger (monster)-islands on the sheet. We study the motion of the particles in a MHD snapshot at a fixed instant of time by the Test-Particle Module incorporated in AMRVAC (). The planar MHD setting artificially causes the largest acceleration in the ignored third direction, but does allow for full analytic study of all aspects leading to the acceleration and the in-plane, projected trapping of particles within embedded mini-islands. The analytic result uses a decomposition of the test particle velocity in slow and fast changing components, akin to the Reynolds decomposition in turbulence studies. The analytic results allow a complete fit to representative proton test particle simulations, which after initial non-relativistic motion throughout the monster island, show the potential of acceleration within a mini-island beyond (√2/2)c≈0.7c, at which speed the acceleration is at its highest efficiency. Acceleration to several hundreds of GeVs can happen within several tens of seconds, for upward traveling protons in counterclockwise mini-islands of sizes smaller than the proton gyroradius.</p> </div> </div> </div><div></div><div></div>

scholarly journals Energy release and conversion by reconnection in the magnetotail

2005 ◽  
Vol 23 (10) ◽  
pp. 3365-3373 ◽  
Author(s):  
J. Birn ◽  
M. Hesse
Keyword(s):  
Energy Transfer ◽  
Energy Release ◽  
Large Scale ◽  
Magnetic Energy ◽  
Minor Role ◽  
Ohmic Dissipation ◽  
Particle Simulations ◽  
Minor Part ◽  
Reconnection Site ◽  
A Minor

Abstract. Magnetic reconnection is the crucial process in the release of magnetic energy previously stored in the magnetotail in association with substorms. However, energy transfer and dissipation in the vicinity of the reconnection site is only a minor part of the energy conversion. We discuss the energy release, transport, and conversion based on large-scale resistive MHD simulations of magnetotail dynamics and more localized full particle simulations of reconnection. We address in particular, where the energy is released, how it propagates and where and how it is converted from one form into another. We find that Joule (or ohmic) dissipation plays only a minor role in the overall energy transfer. Bulk kinetic energy, although locally significant in the outflow from the reconnection site, plays a more important role as mediator or catalyst in the transfer between magnetic and thermal energy. Generator regions with potential auroral consequences are located primarily off the equatorial plane in the boundary regions of the plasma sheet.

HoloRoyale: A Large Scale High Fidelity Augmented Reality Game

2018 ◽  
Author(s):  
Damien Hompapas ◽  
Christian Sandor ◽  
Alexander Plopski ◽  
Daniel Saakes ◽  
Dong Hyeok Yun ◽  
...  
Keyword(s):  
Augmented Reality ◽  
Large Scale ◽  
High Fidelity ◽  
Augmented Reality Game

Efficient Possibilistic Uncertainty Analysis of a Car Crash Scenario Using a Multifidelity Approach

2019 ◽  
Vol 5 (4) ◽  
Author(s):  
Markus Mäck ◽  
Michael Hanss
Keyword(s):  
Uncertainty Analysis ◽  
Large Scale ◽  
Uncertainty Propagation ◽  
Possibility Theory ◽  
Design Stage ◽  
High Fidelity ◽  
Zone Structure ◽  
Early Design Stage ◽  
Car Crash ◽  
Fidelity Model

Abstract The early design stage of mechanical structures is often characterized by unknown or only partially known boundary conditions and environmental influences. Particularly, in the case of safety-relevant components, such as the crumple zone structure of a car, those uncertainties must be appropriately quantified and accounted for in the design process. For this purpose, possibility theory provides a suitable tool for the modeling of incomplete information and uncertainty propagation. However, the numerical propagation of uncertainty described by possibility theory is accompanied by high computational costs. The necessarily repeated model evaluations render the uncertainty analysis challenging to be realized if a model is complex and of large scale. Oftentimes, simplified and idealized models are used for the uncertainty analysis to speed up the simulation while accepting a loss of accuracy. The proposed multifidelity scheme for possibilistic uncertainty analysis, instead, takes advantage of the low costs of an inaccurate low-fidelity model and the accuracy of an expensive high-fidelity model. For this purpose, the functional dependency between the high- and low-fidelity model is exploited and captured in a possibilistic way. This results in a significant speedup for the uncertainty analysis while ensuring accuracy by using only a low number of expensive high-fidelity model evaluations. The proposed approach is applied to an automotive car crash scenario in order to emphasize its versatility and applicability.

Verified fuselage section water impact modelling

2019 ◽  
Vol 123 (1268) ◽  
pp. 1740-1754 ◽  
Author(s):  
Y. Song ◽  
B. Horton ◽  
J. Bayandor
Keyword(s):  
Large Scale ◽  
Structural Response ◽  
High Fidelity ◽  
Water Impact ◽  
Impact Modelling ◽  
Drop Tests ◽  
Section Model ◽  
Aircraft Crashworthiness ◽  
Bodies Of Water

ABSTRACTAlong many flight corridors, bodies of water serve as preferred emergency landing options. Thus, relevant scenarios must be investigated to improve aircraft crashworthiness in the event of an impact landing on water. Enhancing the damage tolerance of aircraft structures through repetitive experiments can, however, prove highly uneconomical. Such large-scale trials can be influenced by many factors of uncertainty adversely affecting the quality of the results. Therefore, the work presented in this study focuses in particular on evaluating a computational methodology perfected for aircraft water ditching using Coupled Lagrangian-Eulerian (CLE) that allows detailed prediction of structural response of a verified deformable fuselage section during such events. Validation of the fluid-structure interactive (FSI) strategy developed is conducted, thoroughly comparing the method against the analytical and experimental results of multiple wedge drop tests. Finally, the validated FSI strategy is applied to a high-fidelity fuselage section model impacting water to simulate and assess a realistic ditching scenario.

Inplementation of an Efficient Parallel Multilevel Fast Multipole Algorithm

2012 ◽  
Vol 433-440 ◽  
pp. 4268-4272
Author(s):  
You Feng Chen ◽  
Dong Lin Su ◽  
Xiao Ying Zhao ◽  
Dan Dan Guo ◽  
Li Peng Deng
Keyword(s):  
Shared Memory ◽  
High Frequency ◽  
Large Scale ◽  
Memory System ◽  
Method Of Moment ◽  
Fast Multipole ◽  
Multilevel Fast Multipole Algorithm ◽  
Shared Memory System ◽  
Fast Multipole Algorithm

This paper is concerned with the implementation of the parallel multilevel fast multipole algorithm(MLFMA) for large scale electromagnetics simulation on shared-memory system. The algorithm is implemented on a method of moment discretisation of the electromagnetics scattering problems.The developed procesure is validated by compared to benchmarks defined by Electromagnetics Code Consortium(EMCC) .The procesure can evaluate large problemssuch as electromagnetics scattering of aircraft at high-frequency with up to several millions of unknowns.

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