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In this paper, an SPH method based on the SPH-ALE formulation is used for modelling two-phase flows with large density ratios and realistic sound speeds. The SPH scheme is further improved to circumvent the tensile instability that may…

Fluid Dynamics · Physics 2020-03-24 Ashkan Rafiee , Denys Dutykh , Frédéric Dias

We calculate numerically the heat transfer rate between a spatially dispersive sphere and a half-space. By utilising Huygens' principle and the extinction theorem, we derive the necessary reflection coefficients at the sphere and the plate…

Optics · Physics 2018-02-14 Robin Schmidt , Stefan Scheel

We present the theoretical framework and numerical methods we have implemented to solve the problem of the generation and transfer of polarized radiation in spectral lines out of local thermodynamical equilibrium, while accounting for…

Solar and Stellar Astrophysics · Physics 2022-09-01 Ernest Alsina Ballester , Luca Belluzzi , Javier Trujillo Bueno

The theory of radiative transfer provides the link between the physical conditions in an astrophysical object and the observable radiation which it emits. Thus accurately modelling radiative transfer is often a necessary part of testing…

Solar and Stellar Astrophysics · Physics 2009-11-10 S. A. Sim , M. Kromer , F. K. Roepke , E. I. Sorokina , S. I. Blinnikov , D. Kasen , W. Hillebrandt

As we approach solar convection simulations that seek to model the interaction of small-scale granulation and supergranulation and even larger scales of convection within the near-surface shear layer (NSSL), the treatment of the boundary…

Solar and Stellar Astrophysics · Physics 2015-05-20 Kyle Augustson , Mark Rast , Regner Trampedach , Juri Toomre

We describe an extension of the cosmological hydrodynamics code ENZO to include the self-consistent transport of ionizing radiation modeled in the flux-limited diffusion approximation. A novel feature of our algorithm is a coupled implicit…

Instrumentation and Methods for Astrophysics · Physics 2015-05-13 Michael L. Norman , Daniel R. Reynolds , Geoffrey C. So

In this article we study the numerical approximation of a variable coefficient fractional diffusion equation. Using a change of variable, the variable coefficient fractional diffusion equation is transformed into a constant coefficient…

Numerical Analysis · Mathematics 2019-02-28 Xiangcheng Zheng , V. J. Ervin , Hong Wang

A tomographic study of near-field radiative heat exchanges between a mesoscopic object and a substrate immersed in a thermal bath is carried out within the theoretical framework of fluctuational electrodynamics. By using the…

Mesoscale and Nanoscale Physics · Physics 2025-01-07 Florian Herz , Riccardo Messina , Philippe Ben-Abdallah

This paper introduces a method to preform optical tomography, using 3D radiative transfer as the forward model. We use an iterative approach predicated on the Spherical Harmonics Discrete Ordinates Method (SHDOM) to solve the optimization…

Atmospheric and Oceanic Physics · Physics 2015-01-27 Aviad Levis , Yoav Y. Schechner , Amit Aides , Anthony B. Davis

We describe and discuss the properties of three numerical methods for solving the diffusion equation for the transport of the chemical species and of the angular momentum in stellar interiors. We study through numerical experiments both…

Astrophysics · Physics 2009-11-10 Georges Meynet , Andre Maeder , Nami Mowlavi

In this paper we present results from a series of hydrodynamical tests aimed at validating the performance of a smoothed particle hydrodynamics (SPH) formulation in which gradients are derived from an integral approach. We specifically…

Instrumentation and Methods for Astrophysics · Physics 2016-11-09 R. Valdarnini

An exact analytical description of the internal radiative field inside an emitting-absorbing gray semi-transparent medium enclosed in a two-dimensional parallelogram cavity is proposed. The expressions of the incident radiation and the…

Optics · Physics 2015-07-07 V. Le Dez , H. Sadat

Radiative heat exchange of spherical particles is recalculated in the framework of fluctuation electrodynamics using the dipole approximation. We show that correct numerical coefficient in the resulting integral expression equals 4/pi, in…

Other Condensed Matter · Physics 2011-02-18 George Dedkov , Arthur Kyasov

We apply an analytical approach for determining the near-field radiative heat transfer between a metallic nanosphere and a planar semi-infinite medium with some given surface structure. This approach is based on a perturbative expansion,…

Mesoscale and Nanoscale Physics · Physics 2015-05-27 Svend-Age Biehs , Oliver Huth , Felix Rüting

In the present study, a discrete forcing Immersed Boundary Method (IBM) is proposed for the numerical simulation of high-speed flow problems including heat exchange. The flow field is governed by the compressible Navier-Stokes equations,…

Fluid Dynamics · Physics 2023-01-24 Hamza Riahi , Eric Goncalves , Marcello Meldi

This paper presents a novel method for smoothed particle hydrodynamics (SPH) with thin-walled structures. Inspired by the direct forcing immersed boundary method, this method employs a moving least square method to guarantee the smoothness…

Fluid Dynamics · Physics 2023-10-10 ZhuoLin Wang , Zichao Jiang , Yi Zhang , Gengchao Yang , Trevor Hocksun Kwan , Yuhui Chen , Qinghe Yao

Radiation hydrodynamics are a challenging multiscale and multiphysics set of equations. To capture the relevant physics of interest, one typically must time step on the hydrodynamics timescale, making explicit integration the obvious…

Numerical Analysis · Mathematics 2024-08-14 Ben S. Southworth , HyeongKae Park , Svetlana Tokareva , Marc Charest

We present an extension of TRAPHIC, the method for radiative transfer of ionising radiation in smoothed particle hydrodynamics simulations that we introduced in Pawlik & Schaye (2008). The new version keeps all advantages of the original…

Instrumentation and Methods for Astrophysics · Physics 2011-05-10 Andreas H. Pawlik , Joop Schaye

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

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