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We present and analyze a space-time Petrov-Galerkin finite element method for a time-fractional diffusion equation involving a Riemann-Liouville fractional derivative of order $\alpha\in(0,1)$ in time and zero initial data. We derive a…

Numerical Analysis · Mathematics 2017-07-26 Beiping Duan , Bangti Jin , Raytcho Lazarov , Joseph Pasciak , Zhi Zhou

We introduce an immersed high-order discontinuous Galerkin method for solving the compressible Navier-Stokes equations on non-boundary-fitted meshes. The flow equations are discretised with a mixed discontinuous Galerkin formulation and are…

Numerical Analysis · Mathematics 2020-01-08 Hong Xiao , Eky Febrianto , Qiaoling Zhang , Fehmi Cirak

A fluorescent image analysis procedure to determine the distribution of species concentration and density in a gas flow is proposed. The fluorescent emission is due to the excitation of atoms/molecules of a gas that is intercepted by an…

Fluid Dynamics · Physics 2009-11-13 Marco Belan , Sergio De Ponte , Daniela Tordella

We revisit the variational characterization of conservative diffusion as entropic gradient flow and provide for it a probabilistic interpretation based on stochastic calculus. It was shown by Jordan, Kinderlehrer, and Otto that, for…

Probability · Mathematics 2020-08-24 Ioannis Karatzas , Walter Schachermayer , Bertram Tschiderer

A discrete spherical harmonics method is developed for the radiative transfer problem in inhomogeneous polarized planar atmosphere illuminated at the top by a collimated sunlight while the bottom reflects the radiation. The method expands…

Instrumentation and Methods for Astrophysics · Physics 2018-02-07 Romuald Tapimo , Hervé Thierry Tagne Kamdem , David Yemele

The paper considers a thermodynamically consistent phase-field model of a two-phase flow of incompressible viscous fluids. The model allows for a non-linear dependence of fluid density on the phase-field order parameter. Driven by…

Numerical Analysis · Mathematics 2023-09-27 Yerbol Palzhanov , Alexander Zhiliakov , Annalisa Quaini , Maxim Olshanskii

We study a turbulence closure model in which the fractional Laplacian $(-\Delta)^\alpha$ of the velocity field represents the turbulence diffusivity. We investigate the energy spectrum of the model by applying Pao's energy transfer theory.…

Numerical Analysis · Mathematics 2016-11-17 Max Gunzburger , Nan Jiang , Feifei Xu

For a model convection-diffusion problem, we obtain new error estimates for a general upwinding finite element discretization based on bubble modification of the test space. The key analysis tool is based on finding representations of the…

Numerical Analysis · Mathematics 2024-02-19 Constantin Bacuta , Cristina Bacuta , Daniel Hayes

Discretization is a fundamental step in numerical analysis for the problems described by differential equations, and the difference between the continuous model and discrete model is one of the most important problems. In this paper, we…

Analysis of PDEs · Mathematics 2020-09-03 Fumihiko Hirosawa

The boundary integral method is extended to derive closed integro-differential equations applicable to computation of the shape and propagation speed of a steadily moving spot and to the analysis of dynamic instabilities in the sharp…

Pattern Formation and Solitons · Physics 2016-09-07 L. M. Pismen

Obtaining a reduced description with particle and momentum flux densities outgoing from the microscopic equations of motion of the particles requires approximations. The usual method, we refer to as truncation method, is to zero Fourier…

Statistical Mechanics · Physics 2017-01-04 Hamid Seyed-Allaei , Lutz Schimansky-Geier , Mohammad Reza Ejtehadi

This work focuses on stability of regime-switching diffusions consisting of continuous and discrete components, in which the discrete component switches in a countably infinite set and its switching rates at current time depend on the…

Probability · Mathematics 2017-10-10 Dang H. Nguyen , George Yin

We consider wave propagation problems over 2-dimensional domains with piecewise-linear boundaries, possibly including scatterers. We assume that the wave speed is constant, and that the initial conditions and forcing terms are radially…

Numerical Analysis · Mathematics 2025-03-14 Davide Pradovera , Monica Nonino , Ilaria Perugia

Cosmic-ray transport in astrophysical environments is often dominated by the diffusion of particles in a magnetic field composed of both a turbulent and a mean component. This process, which is two-fold turbulent mixing in that the particle…

High Energy Astrophysical Phenomena · Physics 2021-12-14 P. Reichherzer , L. Merten , J. Dörner , J. Becker Tjus , M. J. Pueschel , E. G. Zweibel

In our previous publication [Kogan et al, Phys. Rev. {\bf 48}, 9404 (1993)] we considered the issue of statistics of radiation diffusively propagating in a disordered medium. The consideration was in the framework of diagrammatic techniques…

Condensed Matter · Physics 2009-10-22 Eugene Kogan , Moshe Kaveh

We study the time-averaged flow in a model of particles that randomly hop on a finite directed graph. In the limit as the number of particles and the time window go to infinity but the graph remains finite, the large-deviation rate…

Statistical Mechanics · Physics 2020-12-02 Davide Gabrielli , D. R. Michiel Renger

In ecological studies of pattern formation, models of the competitive-diffusion type are generally singularly perturbed, and the numerical approximation of such models is challenging. In this paper, we present finite element discretization…

Numerical Analysis · Mathematics 2026-04-15 Xianping Li , Woinshet D. Mergia , Kailash C. Patidar

Mapping between discrete and continuous distributions is a difficult task and many have had to resort to heuristical approaches. We propose a tessellation-based approach that directly learns quantization boundaries in a continuous space,…

Machine Learning · Computer Science 2022-12-13 Ricky T. Q. Chen , Brandon Amos , Maximilian Nickel

Many natural and industrial systems involve particle-laden interfaces. Because interfacial particles prevent the coalescence and coarsening of drops, they hold promise for various applications requiring stable emulsions. Despite their…

Soft Condensed Matter · Physics 2026-04-08 Alexandros T. Oratis , Matteo Camagna , Timo J. J. M. van Overveld , Valeria Garbin

A popular numerical method to model the dynamics of a 'full spectrum' of cosmic rays (CRs), also applicable to radiation/neutrino hydrodynamics (RHD), is to discretize the spectrum at each location/cell as a piecewise power law in 'bins' of…

High Energy Astrophysical Phenomena · Physics 2022-11-30 Philip F. Hopkins
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