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An analytical solution of the equations describing impurity diffusion due to the migration of nonequilibrium impurity interstitial atoms was obtained for the case of the Robin boundary condition on the surface of a semiconductor. The…

Materials Science · Physics 2008-02-26 O. I. Velichko , N. A. Sobolevskaya

We obtain an approximate global stationary and axisymmetric solution of Einstein's equations which can be thought as a simple star model: a self-gravitating perfect fluid ball with a differential rotation motion pattern. Using the…

General Relativity and Quantum Cosmology · Physics 2017-10-04 A. Molina , E. Ruiz

A granular gas composed of inelastic hard spheres or disks in the homogeneous cooling state is considered. Some of the particles are labeled and their number density exhibits a time-independent linear profile along a given direction. As a…

Statistical Mechanics · Physics 2015-06-18 J. Javier Brey , M. J. Ruiz-Montero

The paper investigates solutions of the fractional hyperbolic diffusion equation in its most general form with two fractional derivatives of distinct orders. The solutions are given as spatial-temporal homogeneous and isotropic random…

Probability · Mathematics 2023-10-09 Nikolai Leonenko , Andriy Olenko , Jayme Vaz

We solve for a system that emits acceleration radiation at two different temperatures. The equilibrium states occur asymptotically in Planck distributions and transition non-thermally. The model is simple enough to obtain a global solution…

General Relativity and Quantum Cosmology · Physics 2021-10-29 Michael R. R. Good , Ayan Mitra , Vasileios Zarikas

A polyatomic ideal gas with weak interaction between the translational and internal modes is considered. For the purpose of describing the behavior of such a gas, a Boltzmann equation is proposed in the form that the collision integral is a…

Analysis of PDEs · Mathematics 2026-03-31 Kazuo Aoki , Niclas Bernhoff

Two-dimensional numerical simulations of an accretion flow in a close binary system are performed by solving the Euler equations with radiative transfer. In the present study, the specific heat ratio is assumed to be constant while…

Astrophysics · Physics 2009-11-07 Jun'ichi Sato , Keisuke Sawada , Naofumi Ohnishi

We obtain, by starting from the balance laws of a continuum endowed with a vectorial microstructure and with a suitable thermodynamics, the evolution equation for the excitation carriers in scintillating crystals. These equations, coupled…

Materials Science · Physics 2018-06-05 Fabrizio Davì

Analytical solutions to heat or diffusion type equations are numerous, but there are rather few explicit solutions for conditions where the thermal conductivity or diffusion tensors are anisotropic. Such solutions have some use in making…

Analysis of PDEs · Mathematics 2015-07-09 Brian D. Wood , Sassan Ostvar

The ultra-relativistic Euler equations for an ideal gas are described in terms of the pressure, the spatial part of the dimensionless four-velocity and the particle density. Radially symmetric solutions of these equations are studied in two…

Mathematical Physics · Physics 2024-02-21 Matthias Kunik , Adrian Kolb , Siegfried Müller , Ferdinand Thein

We present an analytic description of the spherically symmetric gravitational collapse of radiatively cooling gas clouds, which illustrates the mechanism by which radiative cooling induces gravitational instability at a characteristic mass…

Astrophysics of Galaxies · Physics 2025-01-03 James Gurian , Boyuan Liu , Donghui Jeong , Takashi Hosokawa , Shingo Hirano , Naoki Yoshida

This paper proposes a novel reaction-diffusion system approximation tailored for singular diffusion problems, typified by the fast diffusion equation. While such approximation methods have been successfully applied to degenerate parabolic…

Analysis of PDEs · Mathematics 2026-04-01 Hideki Murakawa , Florian Salin

Assuming gauge/gravity correspondence we study reheating of the Universe using its holographic dual. Inflaton decay and thermalisation of the decay products correspond to collapse of a spherical shell and formation of a blackhole in the…

High Energy Physics - Theory · Physics 2016-06-29 Shinsuke Kawai , Yu Nakayama

Radiation transport plays important roles in stellar atmospheres, but the effects of turbulence are being obscured by other effects such as stratification. Using radiative hydrodynamic simulations of forced turbulence, we determine the…

Fluid Dynamics · Physics 2021-09-29 Axel Brandenburg , Upasana Das

We apply moment methods to obtaining an approximate analytical solution to Knudsen layers. Based on the hyperbolic regularized moment system for the Boltzmann equation with the Shakhov collision model, we derive a linearized hyperbolic…

Mathematical Physics · Physics 2021-06-10 Ruo Li , Yichen Yang

In this paper thermal conductivity and thermal diffusivity of a two layer system is examined from the theoretical point of view. We use the one dimensional heat diffusion equation with the appropriate solution in each layer and boundary…

Condensed Matter · Physics 2009-10-28 G. Gonzalez de la Cruz , Yu. G. Gurevich

This paper concerns the existence and properties of traveling wave solutions to reaction-diffusion-convection equations on the real line. We consider a general diffusion term involving the $p$-Laplacian and combustion-type reaction term. We…

Analysis of PDEs · Mathematics 2024-06-26 Pavel Drábek , Michaela Zahradníková

Considering the example of interacting Brownian particles we present a linear response derivation of the boundary condition for the corresponding hydrodynamic description (the diffusion equation). This requires us to identify a non-analytic…

Statistical Mechanics · Physics 2009-11-07 M. Fuchs , K. Kroy

We consider radial decreasing solutions of the semilinear heat equation with exponential nonlinearity. We provide a relatively simple proof of the sharp upper estimates for the final blowup profile and for the refined space-time behavior.…

Analysis of PDEs · Mathematics 2025-04-30 Philippe Souplet

The inversion theorem and convolution theorem of the conformable fractional Laplace transforms are developed. All the elementary properties of the classical Laplace transform are extended to the conformable fractional transform, and using…

Dynamical Systems · Mathematics 2026-05-13 Somnath Sarate , Anil Khairnar , Krishnat Masalkar