Article
Astronomy & Astrophysics
Antoine Bret
Summary: The study shows that the properties of collisionless shocks in a plasma are different from the predictions of the magnetohydrodynamics (MHD) model, due to the stable anisotropy in the upstream or downstream caused by ambient magnetic fields. A model is proposed to derive the downstream anisotropy and shock density jump based on upstream quantities. The case of a parallel shock in pair plasma is considered, and the anisotropy of the upstream, defined as A = T-perpendicular to/T-parallel to, is treated as a free parameter. The behavior of the shock varies for different anisotropy values in the intermediate sonic Mach number range, while being identical to the isotropic upstream case in the strong sonic shock regime.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Antoine Bret
Summary: This study solves a model capable of dealing with perpendicular shocks with anisotropic upstream pressure, which differs from magnetohydrodynamics (MHD). By assuming that the temperature normal to the flow is conserved at the crossing of the shock front, the system of MHD conservation equations is closed. Regardless of the upstream anisotropy, the behavior of a perpendicular shock with isotropic upstream is retrieved in the strong shock sonic limit. A rich variety of behaviors inaccessible to MHD is found depending on the upstream parameters. Differences and similarities with the case of a parallel shock treated in the companion paper MNRAS 520, 6083-6090 (2023) are discussed.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Mechanics
J. Pratt, A. Busse, W-C Mueller
Summary: This study investigates the influence of a magnetic field on anisotropic magnetohydrodynamic (MHD) turbulence using direct numerical simulations. The results show that the diffusion curves of single particles exhibit mildly superdiffusive behaviors in different directions. The dispersion of particle pairs is affected by competing alignment processes, especially at the beginning of the inertial subrange. The observed scaling for relative dispersion is steeper than the Richardson prediction, particularly at larger Reynolds numbers.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Multidisciplinary Sciences
Muni Zhou, Vladimir Zhdankin, Matthew W. Kunz, Nuno F. Loureiro, Dmitri A. Uzdensky
Summary: In this study, we investigate the generation of seed magnetic fields through the Weibel instability in an initially unmagnetized plasma driven by a large-scale shear force. We develop an analytical model and confirm its predictions through particle simulations. This work has important implications for magnetogenesis in dilute astrophysical systems.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Physics, Fluids & Plasmas
Rajesh Kumar, Youichi Sakawa, Takayoshi Sano, Leonard N. K. Dohl, Nigel Woolsey, Alessio Morace
Summary: Intense laser-plasma interactions can generate two electrostatic collisionless shocks at distinct longitudinal positions when driven by a linearly polarized laser in a multicomponent plasma according to two-dimensional particle-in-cell calculations. These shocks exhibit a power-law dependence on the normalized laser vector potential a(0) and accelerate ions to different velocities, suggesting the presence of electrostatic ion two-stream instability. Such particle acceleration processes are common in space and astrophysics, offering exciting possibilities for laboratory studies.
Article
Physics, Fluids & Plasmas
Roopendra Singh Rajawat, Vladimir Khudik, Gennady Shvets
Summary: This study focuses on collisionless shocks generated by colliding relativistic electron-positron plasma shells, showing that kinetic energy of particles interacting with the shock bifurcates into slow and fast groups based on their relativistic Lorentz factors. The anisotropic modification of kinetic energy by WI-induced electric fields is observed, with slow particles affected equally by longitudinal and transverse components, while fast particles primarily accelerated by the transverse field component.
PHYSICS OF PLASMAS
(2021)
Article
Astronomy & Astrophysics
James J. Quinn, Radostin D. Simitev
Summary: Magnetic flux tubes in the solar corona are susceptible to both fluting and kink instabilities. Fluting modes are readily excited by dynamic twisting at the boundaries, especially when plasma viscosity is anisotropic. Although the flute instability cannot prevent the dominance of the kink instability, it can significantly delay its development, particularly in strong viscous anisotropy induced by intense magnetic fields.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Geosciences, Multidisciplinary
Yosuke Matsumoto, Yoshizumi Miyoshi
Summary: In this study, we examined the soft X-ray emission generated by the solar wind charge-exchange process around the Earth's magnetosphere using a global magnetohydrodynamic simulation model. Our findings indicate that the plasma heating and acceleration during the dayside magnetopause reconnection result in a high X-ray brightness, reaching up to 6 x 10(-6) eV cm(-3) s(-1) under southward interplanetary magnetic field conditions. Additionally, we observed that the X-ray intensity reflects the bulk motion of outflows from the reconnection region under low plasma-beta solar wind conditions. These results suggest the possibility of visualizing the mesoscale magnetopause reconnection site using this specific solar wind condition, similar to observations in the solar corona.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Astronomy & Astrophysics
Elias R. Most, Jorge Noronha, Alexander A. Philippov
Summary: This paper describes a fully relativistic covariant two-fluid system with 14 moments for studying electron-ion or electron-positron plasmas. It provides a new formulation that can capture non-ideal effects and the full two-fluid character of collisionless plasmas.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Physics, Multidisciplinary
R. A. Treumann, Wolfgang Baumjohann
Summary: Particle condensates in high-temperature plasmas in magnetic mirror geometries are often caused by a discrete resonance with thermal ion-acoustic background noise. This resonance disrupts bounce symmetry, temporarily trapping particles at the resonant wavelength. The relevant correlation lengths are the Debye length in the parallel direction and the ion gyroradius in the perpendicular direction.
FRONTIERS IN PHYSICS
(2021)
Article
Astronomy & Astrophysics
F. Pucci, M. Viviani, F. Valentini, G. Lapenta, W. H. Matthaeus, S. Servidio
Summary: We demonstrate an efficient mechanism for generating magnetic fields in turbulent, collisionless plasmas through fully kinetic, particle-in-cell simulations. The complex motion is initiated via a Taylor-Green vortex, and the plasma locally develops strong electron temperature anisotropy, due to the strain tensor of the turbulent flow. Subsequently, in a domino effect, the anisotropy triggers a Weibel instability which leads to magnetization.
ASTROPHYSICAL JOURNAL LETTERS
(2021)
Article
Physics, Fluids & Plasmas
Min-Gu Yoo, W. X. Wang, E. Startsev, C. H. Ma, S. Ethier, J. Chen, X. Z. Tang
Summary: The study explores collisionless plasma transport in stochastic magnetic fields connecting to wall boundary, revealing the dynamics of plasma in three-dimensional stochastic open magnetic field lines and the impact on thermal transport. The E x B vortices induced by the 3D ambipolar potential play a crucial role in mixing plasma across stochastic field lines and enhancing radial transport, leading to the loss of high-energy trapped electrons and a steady decrease in electron temperature during thermal quench.
Article
Multidisciplinary Sciences
D. B. Graham, Yu. V. Khotyaintsev, M. Andre, A. Vaivads, A. Divin, J. F. Drake, C. Norgren, O. Le Contel, P. -A. Lindqvist, A. C. Rager, D. J. Gershman, C. T. Russell, J. L. Burch, K. -J. Hwang, K. Dokgo
Summary: The waves contribute to anomalous diffusion but do not contribute to the reconnection electric field. However, they do produce an anomalous electron drift and diffusion across the current layer associated with magnetic reconnection, which modifies the reconnection process.
NATURE COMMUNICATIONS
(2022)
Article
Physics, Multidisciplinary
Eiichirou Kawamori, Yu-Ting Lin
Summary: Researchers provide evidence of an entropy cascade in laboratory plasmas through the visualization of entropy distribution in turbulence. The scaling laws predicted by gyrokinetic theory with the dual self-similarity hypothesis are confirmed.
COMMUNICATIONS PHYSICS
(2022)
Article
Mechanics
Shiying Cai, Chunpei Cai, Edward Lin, David L. Cooke, Jun Li
Summary: In this study, collisionless flows expanding into a vacuum from a circular slit were investigated using the gaskinetic theory. Accurate and approximate expressions for the plume fields were obtained, and particle simulations were performed to validate the results. The investigation also found that simple explicit expressions could be obtained under certain assumptions and indicated that the use of cosine law relations for computing collisionless plume flowfields with a large exit speed is not recommended.
Article
Astronomy & Astrophysics
Masanori Iwamoto, Takanobu Amano, Yosuke Matsumoto, Shuichi Matsukiyo, Masahiro Hoshino
Summary: Particle acceleration at magnetized purely perpendicular relativistic shocks in electron-ion plasmas is studied using two-dimensional particle-in-cell simulations. The results show that highly relativistic astrophysical shocks, such as external shocks of gamma-ray bursts, can serve as efficient particle accelerators.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Alessandro Retino, Yuri Khotyaintsev, Olivier Le Contel, Maria Federica Marcucci, Ferdinand Plaschke, Andris Vaivads, Vassilis Angelopoulos, Pasquale Blasi, Jim Burch, Johan De Keyser, Malcolm Dunlop, Lei Dai, Jonathan Eastwood, Huishan Fu, Stein Haaland, Masahiro Hoshino, Andreas Johlander, Larry Kepko, Harald Kucharek, Gianni Lapenta, Benoit Lavraud, Olga Malandraki, William Matthaeus, Kathryn McWilliams, Anatoli Petrukovich, Jean-Louis Pincon, Yoshifumi Saito, Luca Sorriso-Valvo, Rami Vainio, Robert Wimmer-Schweingruber
Summary: This White Paper highlights the importance of addressing the fundamental science theme of particle energization in space plasmas through a future ESA mission, presenting five compelling science questions and the need for a multi-point, multi-scale Plasma Observatory for in situ measurements. This mission aims to enable a paradigm shift in our comprehension of particle energization and space plasma physics, with significant impacts on solar and astrophysical plasmas, further enhancing European leadership in this field.
EXPERIMENTAL ASTRONOMY
(2022)
Article
Physics, Fluids & Plasmas
Taiki Jikei, Takanobu Amano
Summary: Two different fluid models, the classical Chew-Goldberger-Low (CGL) model and the cyclotron resonance closure (CRC) model, are compared for their applicability in collisionless plasmas. The CGL model better describes the linear property of the parallel firehose instability, while the CRC model successfully reproduces the electromagnetic ion cyclotron instability driven unstable by the cyclotron resonance. Nonlinear simulation results for the parallel firehose instability are also discussed, highlighting the need to incorporate collisionless damping for both longitudinal and transverse modes in a nonlinear fluid simulation model for collisionless plasmas.
PHYSICS OF PLASMAS
(2022)
Article
Astronomy & Astrophysics
K. Keika, S. Kasahara, S. Yokota, M. Hoshino, K. Seki, T. Amano, L. M. Kistler, M. Nose, Y. Miyoshi, T. Hori, I. Shinohara
Summary: During magnetic storms, O+ ions play a significant role in plasma pressure in the inner magnetosphere. Heavier ions are more energized than lighter ions, and lower-charge-state ions are more energized than higher-charge-state ions. The preferential energization is due to temperature increases rather than the generation of energetic ions in the high-energy tail.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Takanobu Amano, Masahiro Hoshino
Summary: This article presents a theory of electron injection into diffusive shock acceleration (DSA) for the generation of cosmic-ray electrons at collisionless shocks. The theory suggests that stochastic shock drift acceleration (SSDA) can be understood as a diffusive particle acceleration mechanism at an oblique shock of finite thickness. It also shows that SSDA is more efficient for low-energy electron acceleration and is favorable for injection. The theory further indicates that efficient acceleration of electrons to ultrarelativistic energies is more easily achieved at high Mach number, young supernova remnant shocks, but not at weak or moderate shocks in the heliosphere unless the upstream magnetic field is nearly perpendicular to the shock normal.
ASTROPHYSICAL JOURNAL
(2022)
Article
Physics, Fluids & Plasmas
Masahiro Hoshino
Summary: The efficiency of nonthermal particle acceleration during magnetic reconnection has been a long-standing question in astrophysics. Recent studies have shown that the production of nonthermal particles becomes more efficient with increasing plasma temperature.
PHYSICS OF PLASMAS
(2022)
Article
Astronomy & Astrophysics
N. K. Walia, K. Seki, T. Amano
Summary: The study explores the structure of the magnetic reconnection region and the acceleration mechanism of particles through 2.5D hybrid simulations. Slow-mode shocks are detected as the reconnection boundary, with detection percentage increasing with distance from the X-point.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Multidisciplinary Sciences
K. Sakai, T. Moritaka, T. Morita, K. Tomita, T. Minami, T. Nishimoto, S. Egashira, M. Ota, Y. Sakawa, N. Ozaki, R. Kodama, T. Kojima, T. Takezaki, R. Yamazaki, S. J. Tanaka, K. Aihara, M. Koenig, B. Albertazzi, P. Mabey, N. Woolsey, S. Matsukiyo, H. Takabe, M. Hoshino, Y. Kuramitsu
Summary: This study reports experimental results on magnetic reconnection, where a pure electron outflow is observed without ion flows. By manipulating the applied magnetic field, the researchers were able to isolate the electron dynamics from the ions. Measurements and observations revealed unique features of electron-scale magnetic reconnection, including plasma structures, parameters, and waves.
SCIENTIFIC REPORTS
(2022)
Article
Astronomy & Astrophysics
T. Yamakawa, K. Seki, T. Amano, Y. Miyoshi, N. Takahashi, A. Nakamizo, K. Yamamoto
Summary: In this study, the excitation mechanisms of storm-time Pc5 waves are investigated using a magnetosphere-ionosphere coupled model. The results show the generation of fundamental mode and second harmonic mode Pc5 waves, with drift resonance and drift-bounce resonance playing important roles in their excitation.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Masahiro Hoshino
Summary: In the process of magnetic reconnection, nonthermal plasma can dominate the total kinetic energy density with more than 90%. Strengthening the guide magnetic field can suppress the efficiency of nonthermal particle acceleration.
ASTROPHYSICAL JOURNAL
(2023)
Article
Physics, Fluids & Plasmas
Yasuhiro Kuramitsu, Yosuke Matsumoto, Takanobu Amano
Summary: The Weibel instability is investigated using relativistic intense short laser pulses, which can generate sub-relativistic high-density collisionless plasmas. By irradiating double parallel planar targets with two relativistic laser pulses, sub-relativistic collisionless counterstreaming plasmas are created.
PHYSICS OF PLASMAS
(2023)
Article
Physics, Fluids & Plasmas
R. Yamazaki, S. Matsukiyo, T. Morita, S. J. Tanaka, T. Umeda, K. Aihara, M. Edamoto, S. Egashira, R. Hatsuyama, T. Higuchi, T. Hihara, Y. Horie, M. Hoshino, A. Ishii, N. Ishizaka, Y. Itadani, T. Izumi, S. Kambayashi, S. Kakuchi, N. Katsuki, R. Kawamura, Y. Kawamura, S. Kisaka, T. Kojima, A. Konuma, R. Kumar, T. Minami, I Miyata, T. Moritaka, Y. Murakami, K. Nagashima, Y. Nakagawa, T. Nishimoto, Y. Nishioka, Y. Ohira, N. Ohnishi, M. Ota, N. Ozaki, T. Sano, K. Sakai, S. Sei, J. Shiota, Y. Shoji, K. Sugiyama, D. Suzuki, M. Takagi, H. Toda, S. Tomita, S. Tomiya, H. Yoneda, T. Takezaki, K. Tomita, Y. Kuramitsu, Y. Sakawa
Summary: We present an experimental method and simulation results to generate quasiperpendicular supercritical magnetized collisionless shocks, which clarify the structures of plasma density and temperatures.
Article
Computer Science, Interdisciplinary Applications
Tian Liang, Lin Fu
Summary: In this work, a new shock-capturing framework is proposed based on a new candidate stencil arrangement and the combination of infinitely differentiable non-polynomial RBF-based reconstruction in smooth regions with jump-like non-polynomial interpolation for genuine discontinuities. The resulting scheme achieves high order accuracy and resolves genuine discontinuities with sub-cell resolution.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Lukas Lundgren, Murtazo Nazarov
Summary: In this paper, a high-order accurate finite element method for incompressible variable density flow is introduced. The method addresses the issues of saddle point system and stability problem through Schur complement preconditioning and artificial compressibility approaches, and it is validated to have high-order accuracy for smooth problems and accurately resolve discontinuities.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Gabriele Ciaramella, Laurence Halpern, Luca Mechelli
Summary: This paper presents a novel convergence analysis of the optimized Schwarz waveform relaxation method for solving optimal control problems governed by periodic parabolic PDEs. The analysis is based on a Fourier-type technique applied to a semidiscrete-in-time form of the optimality condition, which enables a precise characterization of the convergence factor at the semidiscrete level. The behavior of the optimal transmission condition parameter is also analyzed in detail as the time discretization approaches zero.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Jonas A. Actor, Xiaozhe Hu, Andy Huang, Scott A. Roberts, Nathaniel Trask
Summary: This article introduces a scientific machine learning framework that uses a partition of unity architecture to model physics through control volume analysis. The framework can extract reduced models from full field data while preserving the physics. It is applicable to manifolds in arbitrary dimension and has been demonstrated effective in specific problems.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Nozomi Magome, Naoki Morita, Shigeki Kaneko, Naoto Mitsume
Summary: This paper proposes a novel strategy called B-spline based SFEM to fundamentally solve the problems of the conventional SFEM. It uses different basis functions and cubic B-spline basis functions with C-2-continuity to improve the accuracy of numerical integration and avoid matrix singularity. Numerical results show that the proposed method is superior to conventional methods in terms of accuracy and convergence.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Timothy R. Law, Philip T. Barton
Summary: This paper presents a practical cell-centred volume-of-fluid method for simulating compressible solid-fluid problems within a pure Eulerian setting. The method incorporates a mixed-cell update to maintain sharp interfaces, and can be easily extended to include other coupled physics. Various challenging test problems are used to validate the method, and its robustness and application in a multi-physics context are demonstrated.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Xing Ji, Fengxiang Zhao, Wei Shyy, Kun Xu
Summary: This paper presents the development of a third-order compact gas-kinetic scheme for compressible Euler and Navier-Stokes solutions, constructed particularly for an unstructured tetrahedral mesh. The scheme demonstrates robustness in high-speed flow computation and exhibits excellent adaptability to meshes with complex geometrical configurations.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Alsadig Ali, Abdullah Al-Mamun, Felipe Pereira, Arunasalam Rahunanthan
Summary: This paper presents a novel Bayesian statistical framework for the characterization of natural subsurface formations, and introduces the concept of multiscale sampling to localize the search in the stochastic space. The results show that the proposed framework performs well in solving inverse problems related to porous media flows.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Jacob Rains, Yi Wang, Alec House, Andrew L. Kaminsky, Nathan A. Tison, Vamshi M. Korivi
Summary: This paper presents a novel method called constrained optimized DMD with Control (cOptDMDc), which extends the optimized DMD method to systems with exogenous inputs and can enforce the stability of the resulting reduced order model (ROM). The proposed method optimally places eigenvalues within the stable region, thus mitigating spurious eigenvalue issues. Comparative studies show that cOptDMDc achieves high accuracy and robustness.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Andrea La Spina, Jacob Fish
Summary: This work introduces a hybridizable discontinuous Galerkin formulation for simulating ideal plasmas. The proposed method couples the fluid and electromagnetic subproblems monolithically based on source and employs a fully implicit time integration scheme. The approach also utilizes a projection-based divergence correction method to enforce the Gauss laws in challenging scenarios. Numerical examples demonstrate the high-order accuracy, efficiency, and robustness of the proposed formulation.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Junhong Yue, Peijun Li
Summary: This paper proposes two numerical methods (IP-FEM and BP-FEM) to study the flexural wave scattering problem of an arbitrary-shaped cavity on an infinite thin plate. These methods successfully decompose the fourth-order plate wave equation into the Helmholtz and modified Helmholtz equations with coupled conditions on the cavity boundary, providing an effective solution to this challenging problem.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
William Anderson, Mohammad Farazmand
Summary: We develop fast and scalable methods, called RONS, for computing reduced-order nonlinear solutions. These methods have been proven to be highly effective in tackling challenging problems, but become computationally prohibitive as the number of parameters grows. To address this issue, three separate methods are proposed and their efficacy is demonstrated through examples. The application of RONS to neural networks is also discussed.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Marco Caliari, Fabio Cassini
Summary: In this paper, a second order exponential scheme for stiff evolutionary advection-diffusion-reaction equations is proposed. The scheme is based on a directional splitting approach and uses computation of small sized exponential-like functions and tensor-matrix products for efficient implementation. Numerical examples demonstrate the advantage of the proposed approach over state-of-the-art techniques.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Sebastiano Boscarino, Seung Yeon Cho, Giovanni Russo
Summary: This work proposes a high order conservative semi-Lagrangian method for the inhomogeneous Boltzmann equation of rarefied gas dynamics. The method combines a semi-Lagrangian scheme for the convection term, a fast spectral method for computation of the collision operator, and a high order conservative reconstruction and a weighted optimization technique to preserve conservative quantities. Numerical tests demonstrate the accuracy and efficiency of the proposed method.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Jialei Li, Xiaodong Liu, Qingxiang Shi
Summary: This study shows that the number, centers, scattering strengths, inner and outer diameters of spherical shell-structured sources can be uniquely determined from the far field patterns. A numerical scheme is proposed for reconstructing the spherical shell-structured sources, which includes a migration series method for locating the centers and an iterative method for computing the inner and outer diameters without computing derivatives.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
