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We present a new method for constructing equilibrium phase models for stellar systems, which we call the iterative method. It relies on constrained, or guided evolution, so that the equilibrium solution has a number of desired parameters…

Astrophysics · Physics 2009-11-13 S. A. Rodionov , E. Athanassoula , N. Ya Sotnikova

Exascale super-computers now becoming available rely on hybrid energy-efficient architectures that involve an accelerator such as Graphics Processing Units (GPU). Leveraging the computational power of these machines often means a…

Instrumentation and Methods for Astrophysics · Physics 2023-08-30 G. R. J. Lesur , S. Baghdadi , G. Wafflard-Fernandez , J. Mauxion , C. M. T. Robert , M. Van den Bossche

The early evolution of unstable hydrodynamic and magnetohydrodynamic equilibria is often governed by a few dominant linear eigenmodes. We investigate whether initialising a simulation with a superposition of linear eigenmodes that contains…

Instrumentation and Methods for Astrophysics · Physics 2026-03-02 Jordi De Jonghe , Alexander J. B. Russell

Atmospheric dynamics span a range of time-scales. The projection of measured data to a slow manifold, ${\cal M}$, removes fast gravity waves from the initial state for numerical simulations of the atmosphere. We explore further the slow…

Chaotic Dynamics · Physics 2007-05-23 S. M. Cox , A. J. Roberts

The transport of energy through radiation is very important in many astrophysical phenomena. In dynamical problems the time-dependent equations of radiation hydrodynamics have to be solved. We present a newly developed…

Earth and Planetary Astrophysics · Physics 2015-06-17 Stefan M. Kolb , Matthias Stute , Wilhelm Kley , Andrea Mignone

We address the question of parameterizing the subgrid scales in simulations of geophysical flows by applying stochastic mode reduction to the one-dimensional stochastically forced shallow water equations. The problem is formulated in…

Fluid Dynamics · Physics 2018-08-17 Matthias Zacharuk , Stamen I. Dolaptchiev , Ulrich Achatz , Ilya Timofeyev

Aims. The importance of radiation to the physical structure of protoplanetary disks cannot be understated. However, protoplanetary disks evolve with time, and so to understand disk evolution and by association, disk structure, one should…

Instrumentation and Methods for Astrophysics · Physics 2015-02-04 J. P. Ramsey , C. P. Dullemond

We carry out several isolated galaxy evolution simulations in a fixed dark matter halo gravitational potential using the new version of our N-body/Smoothed Particle Hydrodynamics (SPH) code GCD+. The new code allows us to more accurately…

Astrophysics of Galaxies · Physics 2015-06-03 Awat Rahimi , Daisuke Kawata

A higher order Godunov method for the radiation subsystem of radiation hydrodynamics is presented. A key ingredient of the method is the direct coupling of stiff source term effects to the hyperbolic structure of the system of conservation…

Numerical Analysis · Mathematics 2009-10-09 Michael Sekora , James Stone

We explore the application of Monte Carlo transport methods to solving coupled radiation-hydrodynamics problems. We use a time-dependent, frequency-dependent, 3-dimensional radiation transport code, that is special relativistic and includes…

Instrumentation and Methods for Astrophysics · Physics 2015-06-19 Nathaniel Roth , Daniel Kasen

The structure of the initial system-environment state is fundamental to determining the nature and characteristics of the evolution of such an open quantum system. The usual assumption is to consider that the initial system-environment…

Quantum Physics · Physics 2017-05-17 Jad C. Halimeh , Ines de Vega

This report describes a new magnetohydrodynamic numerical model based on a hexagonal spherical geodesic grid. The model is designed to simulate astrophysical flows of partially ionized plasmas around a central compact object, such as a star…

Instrumentation and Methods for Astrophysics · Physics 2015-06-15 V. Florinski , X. Guo , D. S. Balsara , C. Meyer

Stellar evolution codes play a major role in present-day astrophysics, yet they share common issues. In this work we seek to remedy some of those by the use of results from realistic and highly detailed 3D hydrodynamical simulations of…

We conduct 3D magneto-hydrodynamic (MHD) simulations in order to test the stability of the magnetic equilibrium configuration described by Duez & Mathis (2010). This analytically-derived configuration describes the lowest energy state for a…

Solar and Stellar Astrophysics · Physics 2015-05-20 V. Duez , J. Braithwaite , S. Mathis

Mergers of two carbon-oxygen white dwarfs have long been suspected to be progenitors of Type Ia Supernovae. Here we present our modifications to the cosmological smoothed particle hydrodynamics code Gadget to apply it to stellar physics…

High Energy Astrophysical Phenomena · Physics 2015-06-05 R. Pakmor , P. Edelmann , F. K. Roepke , W. Hillebrandt

Radiation hydrodynamical transport of ionization fronts in the next generation of cosmological reionization simulations holds the promise of predicting UV escape fractions from first principles as well as investigating the role of…

Astrophysics · Physics 2009-11-11 Daniel J. Whalen , Michael L. Norman

I provide a pedagogic review of adaptive mesh refinement (AMR) radiation hydrodynamics (RHD) methods and codes used in simulations of star formation, at a level suitable for researchers who are not computational experts. I begin with a…

Instrumentation and Methods for Astrophysics · Physics 2015-05-19 Mark R. Krumholz

The photoionization-driven evaporation of planetary atmospheres has emerged as a potentially fundamental process for planets on short period orbits. While 1-D studies have proven the effectiveness of stellar fluxes at altering the…

Earth and Planetary Astrophysics · Physics 2018-12-19 Alex Debrecht , Jonathan Carroll-Nellenback , Adam Frank , John McCann , Ruth Murray-Clay , Eric G. Blackman

We demonstrate that Pleba\'nski's first heavenly equation decouples in infinitely many ways into a triple of commuting (1+1)-dimensional systems of hydrodynamic type which satisfy the Egorov property. Solving these systems by the…

Exactly Solvable and Integrable Systems · Physics 2009-11-10 E. V. Ferapontov , M. V. Pavlov

We present the results of a series of calculations studying the collapse of molecular cloud cores performed using a three-dimensional smoothed particle hydr odynamics code with radiative transfer in the flux-limited diffusion approximation.…

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