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We study systematically stationary solutions to the coupled Vlasov and Poisson equations which have `self-similar' or scaling symmetry in phase space. In particular, we find analytically {\it all} spherically symmetric distribution…

Astrophysics · Physics 2015-06-24 R. N. Henriksen , Lawrence M. Widrow

Pseudospectral schemes are a class of numerical methods capable of solving smooth problems with high accuracy thanks to their exponential convergence to the true solution. When applied to discontinuous problems, such as fluid shocks and…

Numerical Analysis · Mathematics 2019-10-03 Joanna Piotrowska , Jonah M. Miller

Blow-up in second and fourth order semi-linear parabolic partial differential equations (PDEs) is considered in bounded regions of one, two and three spatial dimensions with uniform initial data. A phenomenon whereby singularities form at…

Analysis of PDEs · Mathematics 2013-12-04 A. E. Lindsay

For a singularly perturbed system of reaction--diffusion equations, assuming that the 0th order solutions in regular and singular regions are all stable, we construct matched asymptotic expansions for formal solutions to any desired order…

patt-sol · Physics 2008-02-03 Xiao-Biao Lin

We are concerned with a global existence theory for finite-energy solutions of the multidimensional Euler-Poisson equations for both compressible gaseous stars and plasmas with large initial data of spherical symmetry. One of the main…

Analysis of PDEs · Mathematics 2023-11-14 Gui-Qiang G. Chen , Lin He , Yong Wang , Difan Yuan

Self-similar shock solutions in spherically symmetric polytropic gas flows are constructed and analyzed in contexts of proto-star formation processes. Among other possible solutions, we model a similarity shock across the sonic critical…

Astrophysics · Physics 2009-11-11 Yu-Qing Lou , Yang Gao

Differential equations (DEs) are commonly used to describe dynamic systems evolving in one (ordinary differential equations or ODEs) or in more than one dimensions (partial differential equations or PDEs). In real data applications the…

Methodology · Statistics 2013-11-25 Gianluca Frasso , Jonathan Jaeger , Philippe Lambert

The gas of the interacted electrons is usually described within Kohn-Sham approximation by the set of Poisson and Schr\"{o}dinger equations with an effective potential for the single-particle wave functions. The solution of these equations…

Materials Science · Physics 2007-05-23 A. Ya. Shul'man , D. V. Posvyanskii

In the theory of diffusive acceleration at oblique shock fronts the question of the existence of a discontinuity of energetic particle density is contentious. The resolution of this problem is interesting from a theoretical point of view,…

Astrophysics · Physics 2011-05-23 U. D. J. Gieseler , J. G. Kirk , Y. A. Gallant , A. Achterberg

We apply the asymptotic iteration method (AIM) [J. Phys. A: Math. Gen. 36, 11807 (2003)] to solve new classes of second-order homogeneous linear differential equation. In particular, solutions are found for a general class of eigenvalue…

Mathematical Physics · Physics 2009-11-10 Hakan Ciftci , Richard L. Hall , Nasser Saad

We use a connection between relativistic hydrodynamics and scalar field theory to generate exact analytic solutions describing non-stationary inhomogeneous flows of the perfect fluid with one-parametric equation of state (EOS) $p =…

Mathematical Physics · Physics 2008-12-19 Maxim S. Borshch , Valery I. Zhdanov

To simulate the expansion of the matter created in relativistic nuclear collisions, codes in 3+1 dimensions are used and we are developing a new one. To benchmark such codes, the Sod's shock tube is often used. A closely related problem is…

High Energy Physics - Phenomenology · Physics 2022-10-19 J V O Caetano , L S Nowacki , V S Franção , R Hirayama , K P Pala , J O Sola , F Grassi

Probabilistic ordinary differential equation (ODE) solvers have been introduced over the past decade as uncertainty-aware numerical integrators. They typically proceed by assuming a functional prior to the ODE solution, which is then…

Numerical Analysis · Mathematics 2025-03-25 Yvann Le Fay , Simo Särkkä , Adrien Corenflos

The porous medium equation (PME) is a typical nonlinear degenerate parabolic equation. An energetic variational approach has been studied in a recent work [6], in which the trajectory equation is obtained, and a few first order accurate…

Numerical Analysis · Mathematics 2020-06-23 Chenghua Duan , Wenbin Chen , Chun Liu , Cheng Wang , Xingye Yue

The problem of a non-steady planar radiation mediated shock (RMS) breaking out from a surface with a power-law density profile, \rho\propto x^n, is numerically solved in the approximation of diffusion with constant opacity. For an…

High Energy Astrophysical Phenomena · Physics 2015-05-27 Nir Sapir , Boaz Katz , Eli Waxman

The solution for the radial distribution of pressure, density, temperature and flow velocity fields in a blast wave propagating through a medium at rest, following an intense explosion, starting from hydrodynamic equations, is one of the…

Statistical Mechanics · Physics 2018-12-11 Jilmy P. Joy , Sudhir N. Pathak , R. Rajesh

An analytical solution based on a diffuse interface model is presented for an isothermal evaporation problem under sub-saturation pressure. The macroscopic equations are derived from the free-energy method, widely recognized in the lattice…

We study the Riemann problem for the isentropic compressible Euler equations in two space dimensions with the pressure law describing the Chaplygin gas. It is well known that there are Riemann initial data for which the 1D Riemann problem…

Analysis of PDEs · Mathematics 2018-09-17 Jan Březina , Ondřej Kreml , Václav Mácha

This article is a study about the existence and the uniqueness of solutions of a specific quadratic first-order ODE that frequently appears in multiple reconstruction problems. It is called the \emph{planar-perspective equation} due to the…

Numerical Analysis · Computer Science 2018-06-28 David Casillas-Perez , Daniel Pizarro , Manuel Mazo , Adrien Bartoli

We study the exchange of stability in scalar reaction-diffusion equations which feature a slow passage through transcritical and pitchfork type singularities in the reaction term, using a novel adaptation of the geometric blow-up method.…

Dynamical Systems · Mathematics 2024-11-22 Samuel Jelbart , Christian Kuehn , Alejandro Martínez Sánchez