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This work presents efficient solution techniques for radiative transfer in the smoothed particle hydrodynamics discretization. Two choices that impact efficiency are how the material and radiation energy are coupled, which determines the…

Computational Physics · Physics 2021-03-17 Brody R. Bassett , J. Michael Owen , Thomas A. Brunner

The recently developed iterated stockholder atoms (ISA) approach of Lillestolen and Wheatley (Chem. Commun. {\bf 2008}, 5909 (2008)) offers a powerful method for defining atoms in a molecule. However, the real-space algorithm is known to…

Materials Science · Physics 2014-09-23 Alston J. Misquitta , Anthony J. Stone , Farhang Fazeli

The simulation of atmospheric flows by means of traditional discretization methods remains computationally intensive, hindering the achievement of high forecasting accuracy in short time frames. In this paper, we apply three reduced order…

Fluid Dynamics · Physics 2023-07-19 Arash Hajisharifi , Michele Girfoglio , Annalisa Quaini , Gianluigi Rozza

We use a three-specie fluid model of electric discharge in air to simulate streamer evolution from the avalanche-to-streamer transition to the collision of opposite-polarity streamers. We estimate the upper limit on the production of…

Space Physics · Physics 2018-08-03 Nikolai G. Lehtinen , Nikolai Østgaard

We study nondipole effects in multiphoton ionization of a two-dimensional hydrogen-like atom by a flat-top laser pulse of varied intensity. For this purpose, we solve numerically a two-dimensional Schr\"odinger equation treating a…

Atomic Physics · Physics 2024-12-25 J. Z. Kamiński , K. Krajewska

Particle methods are less computationally efficient than grid based numerical solution of the Navier Stokes equation. However, they have important advantages including rigorous mass conservation, momentum conservation and isotropy. In…

Fluid Dynamics · Physics 2024-06-26 Paul Meakin , Zhijie Xu

To make relevant predictions about observable emission, hydrodynamical simulation codes must employ schemes that account for radiative losses, but the large dimensionality of accurate radiative transfer schemes is often prohibitive.…

Instrumentation and Methods for Astrophysics · Physics 2015-06-23 James C. Lombardi , William G. McInally , Joshua A. Faber

Many applications of computational fluid dynamics require multiple simulations of a flow under different input conditions. In this paper, a numerical algorithm is developed to efficiently determine a set of such simulations in which the…

Numerical Analysis · Mathematics 2017-05-29 Max Gunzburger , Nan Jiang , Zhu Wang

Image simulation for scanning transmission electron microscopy at atomic resolution for samples with realistic dimensions can require very large computation times using existing simulation algorithms. We present a new algorithm named PRISM…

Materials Science · Physics 2017-04-24 Colin Ophus

Photoionization of an atom $A$ by a strong laser field in the presence of a spatially well-separated neighboring atom $B$ is considered. The laser field frequency is assumed to lie below the ionization potential of atom $A$ and be resonant…

Atomic Physics · Physics 2018-10-03 J. Fedyk , A. B. Voitkiv , C. Müller

Accurate performance estimation of future many-node machines is challenging because it requires detailed simulation models of both node and network. However, simulating the full system in detail is unfeasible in terms of compute and memory…

Performance · Computer Science 2024-01-19 Stijn Eyerman , Wim Heirman , Kristof Du Bois , Ibrahim Hur

A numerical method based upon the immersed boundary technique for the fluid-solid coupling and on a soft-sphere approach for solid-solid contact is used to perform direct numerical simulation of the flow-induced motion of a thick bed of…

Fluid Dynamics · Physics 2014-10-01 Aman G. Kidanemariam , Markus Uhlmann

Large classes of materials systems in physics and engineering are governed by magnetic and electrostatic interactions. Continuum or mesoscale descriptions of such systems can be cast in terms of integral equations, whose direct…

Computational Physics · Physics 2016-08-15 Xikai Jiang , Jiyuan Li , Xujun Zhao , Jian Qin , Dmitry Karpeev , Juan Hernandez-Ortiz , Juan de Pablo , Olle Heinonen

In this paper, we present a fast streamline-based numerical method for the two-phase flow equations in high-rate flooding scenarios for incompressible fluids in heterogeneous and anisotropic porous media. A fractional flow formulation is…

Numerical Analysis · Mathematics 2018-11-29 Ettore Vidotto , Martin Schneider , Rainer Helmig , Barbara Wohlmuth

Streamers often constitute the first stage of dielectric breakdown in strong electric fields: a nonlinear ionization wave transforms a non-ionized medium into a weakly ionized nonequilibrium plasma. New understanding of this old phenomenon…

patt-sol · Physics 2016-09-08 Ute Ebert , Wim van Saarloos , Christiane Caroli

We formulate a computationally efficient time-independent method based on the multi-electron molecular R-matrix formalism. This method is used to calculate transition matrix elements for the multi-photon ionization of atoms and molecules…

Atomic Physics · Physics 2022-05-10 Jakub Benda , Zdeněk Mašín

We consider a variational method to solve the optical flow problem with varying illumination. We apply an adaptive control of the regularization parameter which allows us to preserve the edges and fine features of the computed flow. To…

Computer Vision and Pattern Recognition · Computer Science 2015-08-13 Diane Gilliocq-Hirtz , Zakaria Belhachmi

The direct and indirect boundary element methods, accelerated via the fast multipole method, are applied to numerical simulation of room acoustics for large rooms of volume $\sim 150$ $m^{3}$ and frequencies up to 5 kHz on a workstation. As…

Numerical Analysis · Mathematics 2021-09-22 Nail A. Gumerov , Ramani Duraiswami

Multiscale mixed methods based on non-overlapping domain decompositions can efficiently handle the solution of significant subsurface flow problems in very heterogeneous formations of interest to the industry, especially when implemented on…

Numerical Analysis · Mathematics 2025-02-25 Dilong Zhou , Rafael Guiraldello , Felipe Pereira

A three dimensional parallel implementation of Multiscale Mixed Methods based on non-overlapping domain decomposition techniques is proposed for multi-core computers and its computational performance is assessed by means of numerical…

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