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We develop a framework for on-the-fly machine learned force field (MLFF) molecular dynamics (MD) simulations of warm dense matter (WDM). In particular, we employ an MLFF scheme based on the kernel method and Bayesian linear regression, with…

Computational Physics · Physics 2024-02-22 Shashikant Kumar , Xin Jing , John E. Pask , Phanish Suryanarayana

We present a stable finite element method for incompressible nonlinear elasticity based on a four-field mixed formulation involving the displacement, displacement gradient, first Piola--Kirchhoff stress and pressure. Unlike existing…

Numerical Analysis · Mathematics 2026-03-11 Santiago Badia , Wei Li , Ricardo Ruiz-Baier

We study large-scale dynamo action due to turbulence in the presence of a linear shear flow. Our treatment is quasilinear and equivalent to the standard `first order smoothing approximation'. However it is non perturbative in the shear…

Astrophysics of Galaxies · Physics 2010-02-16 S. Sridhar , Kandaswamy Subramanian

The effect of compressibility in charged particle energization by magnetohydrodynamic (MHD) fields is studiedin the context of test particle simulations. This problem is relevant to the solar wind and the solar corona due to the…

Plasma Physics · Physics 2016-08-24 C. A. González , P. Dmitruk , P. D. Mininni , W. H. Matthaeus

We perform global three-dimensional simulations of accretion disks integrating the compressible, non-viscous, but diffusive MHD equations. The disk is supposed to be isothermal. We make use of the ZEUS-3D code integrating the MHD equations…

Astrophysics · Physics 2009-11-06 R. Arlt , G. Rudiger

The Davis-Chandrasekhar-Fermi (DCF) method is widely employed to estimate the mean magnetic field strength in astrophysical plasmas. In this study, we present a numerical investigation using the DCF method in conjunction with a promising…

Instrumentation and Methods for Astrophysics · Physics 2023-05-10 Parth Pavaskar , Huirong Yan , Jungyeon Cho

A comparative study on mesh-based and mesh-less Computational Fluid Dynamics (CFD) approaches coupled with the Discrete Element Method (DEM) is presented. As the mesh-based CFD approach a Finite Volume Method (FVM) is used. A Smoothed…

Fluid Dynamics · Physics 2016-09-28 D. Markauskas , H. Kruggel-Emden , R. Sivanesapillai , H. Steeb

We investigate the magnetic-field-induced frequency shift (MFS) of the clock "0-0" transition in the microwave quantum frequency standard (atomic clock) based on coherent population trapping (CPT) in $^{87}$Rb vapor. To scan the CPT…

Atomic Physics · Physics 2025-04-28 V. I. Vishnyakov , D. V. Brazhnikov , M. N. Skvortsov

A joint effect of the density-stratified turbulence (or inhomogeneous turbulence) and a large-scale shear for arbitrary Mach numbers results in the $\alpha$ effect and mean-field dynamo action. These effects also produce the effective…

Astrophysics of Galaxies · Physics 2026-03-19 Igor Rogachevskii , Nathan Kleeorin

Aims: To determine alpha effect and turbulent magnetic diffusivity for mean magnetic fields with profiles of different length scale from simulations of isotropic turbulence, and to relate these results to nonlocal formulations in which…

Astrophysics · Physics 2008-04-30 A. Brandenburg , K. -H. Rädler , M. Schrinner

In this paper we present a novel pressure-based semi-implicit finite volume solver for the equations of compressible ideal, viscous and resistive magnetohydrodynamics (MHD). The new method is conservative for mass, momentum and total energy…

Numerical Analysis · Mathematics 2018-12-26 Michael Dumbser , Dinshaw S. Balsara , Maurizio Tavelli , Francesco Fambri

(abridged) Aims: Three-dimensional numerical simulations of penetrative compressible convection with uniform horizontal shear are used to study dynamo action and the generation of large-scale magnetic fields. Methods: We consider cases…

Astrophysics · Physics 2008-11-10 P. J. Käpylä , M. J. Korpi , A. Brandenburg

Probing magnetic fields in the interstellar medium (ISM) is notoriously challenging. Motivated by the modern theories of magnetohydrodynamic (MHD) turbulence and turbulence anisotropy, we introduce the Structure-Function Analysis (SFA) as a…

Astrophysics of Galaxies · Physics 2021-04-21 Yue Hu , Siyao Xu , A. Lazarian

We perform a mean-field analysis of the EULAG-MHD millenium simulation of global magnetohydrodynamical convection presented in Passos et al. 2014. The turbulent electromotive force operating in the simulation is assumed to be linearly…

Solar and Stellar Astrophysics · Physics 2016-04-07 C. Simard , P. Charbonneau , C. Dube

When scale separation in space and time is poor, the alpha effect and turbulent diffusivity have to be replaced by integral kernels. Earlier work in computing these kernels using the test-field method is now generalized to the case in which…

Solar and Stellar Astrophysics · Physics 2012-01-11 M. Rheinhardt , A. Brandenburg

We introduce a method for computing quantum mechanical forces through surface integrals over the stress tensor within the framework of density functional theory. This approach avoids the inaccuracies of traditional force calculations using…

Chemical Physics · Physics 2025-01-31 Moritz Gubler , Jonas A. Finkler , Stig Rune Jensen , Stefan Goedecker , Luca Frediani

We study mean-field dynamo action in a background linear shear flow by employing pulsed renewing flows with fixed kinetic helicity and nonzero correlation time ($\tau$). We use plane shearing waves in terms of time-dependent exact solutions…

Solar and Stellar Astrophysics · Physics 2020-05-13 Naveen Jingade , Nishant K. Singh

A plane-shear flow in a fluid with forced turbulence is considered. If the fluid is electrically-conducting then a mean electromotive force (EMF) results even without basic rotation and the magnetic diffusivity becomes a highly anisotropic…

Astrophysics · Physics 2009-11-11 G. Ruediger , L. L. Kitchatinov

Dust polarization is a powerful tool for studying the magnetic field properties in the interstellar medium (ISM). However, it does not provide a direct measurement of its strength. Different methods havebeen developed which employ both…

Astrophysics of Galaxies · Physics 2021-04-07 Raphael Skalidis , Konstantinos Tassis

We derive the transient-time correlation function (TTCF) expression for the computation of phase variables of inhomogenous confined atomistic fluids undergoing boundary-driven planar shear (Couette) flow at constant pressure. Using…

Soft Condensed Matter · Physics 2022-05-24 Luca Maffioli , Edward R. Smith , James P. Ewen , Peter J. Daivis , Daniele Dini , B. D. Todd