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In this article we develop an algorithm for the efficient simulation of electrolytes in the presence of physical boundaries. In previous work the Discrete Ion Stochastic Continuum Overdamped Solvent (DISCOS) algorithm was derived for triply…

We develop a numerical hydrodynamics code using a pseudo-Newtonian formulation that uses the weak field approximation for the geometry, and a generalized source term for the Poisson equation that takes into account relativistic effects. The…

High Energy Astrophysical Phenomena · Physics 2015-06-04 Jinho Kim , Hee Il Kim , Matthew William Choptuik , Hyung Mok Lee

The cosmic reionization of hydrogen was the last major phase transition in the evolution of the universe, which drastically changed the ionization and thermal conditions in the cosmic gas. To the best of our knowledge today, this process…

Cosmology and Nongalactic Astrophysics · Physics 2011-06-03 Hy Trac , Nickolay Y. Gnedin

In the Simulations and Constructions of the Reionization of Cosmic Hydrogen (SCORCH) project, we compare analytical models of the hydrogen ionization fraction with radiation-hydrodynamic simulations. We derive analytical models of the…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-28 Nianyi Chen , Aristide Doussot , Hy Trac , Renyue Cen

Three non-equilibrium photoionisation algorithms for hydrodynamical grid-based simulation codes are compared in terms of accuracy, timestepping criteria, and parallel scaling. Explicit methods with first-order time accuracy for photon…

Astrophysics of Galaxies · Physics 2012-03-09 Jonathan Mackey

A possible inconsistency arising when a radiative cooling term is incorporated in a finite resolution self-gravitating hydrodynamic code is discussed. The inconsistency appears when the heating-cooling balance within the cooling and…

Astrophysics · Physics 2015-06-24 Nickolay Y. Gnedin

We report on recent upgrades to our general relativistic radiation-magnetohydrodynamics code, Cosmos++, which expands the two-moment, $\bf{M}_1$, radiation treatment from grey to multi-frequency transport, including Doppler and…

Instrumentation and Methods for Astrophysics · Physics 2020-09-09 Peter Anninos , P. Chris Fragile

We describe a new, faster implicit algorithm for solving the radiation hydrodynamics equations in the flux-limited diffusion approximation for smoothed particle hydrodynamics. This improves on the method elucidated in Whitehouse & Bate by…

Astrophysics · Physics 2009-11-13 Stuart C. Whitehouse , Matthew R. Bate , Joe J. Monaghan

We have developed a parallel cosmological hydrodynamic simulation code designed for the study of formation and evolution of cosmological structures. The gravitational force is calculated using the TreePM method and the hydrodynamics is…

Astrophysics of Galaxies · Physics 2017-01-18 Jihye Shin , Juhan Kim , Sungsoo S. Kim , Changbom Park

The quasi-neutral hybrid model with kinetic ions and fluid electrons is a promising approach for bridging the inherent multi-scale nature of many problems in space and laboratory plasmas. Here, a novel, implicit, particle-in-cell based…

Plasma Physics · Physics 2018-11-14 A. Stanier , L. Chacón , G. Chen

We describe the implementation and testing of a smoothed particle hydrodynamics (SPH) code that solves the equations of radiation hydrodynamics in the flux-limited diffusion (FLD) approximation. The SPH equations of radiation hydrodynamics…

Astrophysics · Physics 2009-11-10 Stuart C. Whitehouse , Matthew R. Bate

The ionization of atomic hydrogen in intense laser fields is studied theoretically. The calculations were performed applying both quantummechanical and classical approaches. Treating the problem quantummechanically, the time dependent…

Atomic Physics · Physics 2009-11-13 S. Borbély , K. Tőkési , L. Nagy

The characterisation of the atomic and molecular hydrogen content of high-redshift galaxies is a major observational challenge that will be addressed over the coming years with a new generation of radio telescopes. We investigate this…

Cosmology and Nongalactic Astrophysics · Physics 2012-04-13 Alan R. Duffy , Scott T. Kay , Richard A. Battye , C. M. Booth , Claudio Dalla Vecchia , Joop Schaye

Numerical methods for radiative transfer play a key role in modern-day astrophysics and cosmology, including study of the inhomogeneous reionization process. In this context, ray tracing methods are well-regarded for accuracy but notorious…

Instrumentation and Methods for Astrophysics · Physics 2025-12-16 Nathan X. Marshak , Kathlynn Simotas , Zarija Lukić , Hyunbae Park , James Ahrens , Chris R. Johnson

We present two new Lagrangian methods for hydrodynamics, in a systematic comparison with moving-mesh, SPH, and stationary (non-moving) grid methods. The new methods are designed to simultaneously capture advantages of both smoothed-particle…

Cosmology and Nongalactic Astrophysics · Physics 2015-12-15 Philip F. Hopkins

An implicit Lagrangian hydrodynamics code for general relativistic spherical collapse is presented. This scheme is based on an approximate linearized Riemann solver (Roe type scheme). This code is aimed especially at the calculation of the…

Astrophysics · Physics 2009-10-28 Shoichi Yamada

We compare numerical methods for solving the radiative transfer equation in the context of the photoionization of intergalactic gaseous hydrogen and helium by a central radiating source. Direct integration of the radiative transfer equation…

Instrumentation and Methods for Astrophysics · Physics 2023-01-18 Ka-Hou Leong , Avery Meiksin , Althea Lai , K. H. To

We present a numerical algorithm for the incorporation of the active cosmic ray transport, into the ZEUS-3D magnetohydrodynamical code. The cosmic ray transport is described by the diffusion-advection equation. The applied form of the…

Astrophysics · Physics 2009-11-10 M. Hanasz , H. Lesch

In this paper, we extend the operator-split asymptotic-preserving, semi-Lagrangian algorithm for time dependent anisotropic heat transport equation proposed in [Chac\'on et al., JCP, 272, 719-746, 2014] to use a fully implicit time…

Plasma Physics · Physics 2024-04-16 O. Koshkarov , L. Chacon

We use the alternating direction method to simulate implicit dynamics. ur spatial discretization uses isogeometric analysis. Namely, we simulate a (hyperbolic) wave propagation problem in which we use tensor-product B-splines in space and…

Numerical Analysis · Mathematics 2019-11-20 Marcin Los , Pouria Behnoudfar , Maciej Paszynski , Victor Manuel Calo
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