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We study traveling waves for a reaction-diffusion equation with nonlocal anisotropic diffusion and a linear combination of local and nonlocal monostable-type reactions. We describe relations between speeds and asymptotic of profiles of…

Analysis of PDEs · Mathematics 2018-04-30 Dmitri Finkelshtein , Yuri Kondratiev , Pasha Tkachov

In this series of papers, we investigate the spreading and vanishing dynamics of time almost periodic diffusive KPP equations with free boundaries. Such equations are used to characterize the spreading of a new species in time almost…

Dynamical Systems · Mathematics 2015-07-08 Fang Li , Xing Liang , Wenxian Shen

We investigated a nonlinear advection-diffusion-reaction equation for a passive scalar field. The purpose is to understand how the compressibility can affect the front dynamics and the bulk burning rate. We study two classes of flows:…

Biological Physics · Physics 2013-07-01 Federico Bianco , Sergio Chibbaro , Davide Vergni , Angelo Vulpiani

We introduce a new velocity selection criterion for fronts propagating into unstable and metastable states. We restrict these fronts to large finite intervals in the comoving frame of reference and require their centers be insensitive to…

Pattern Formation and Solitons · Physics 2009-10-31 Stavros Theodorakis , Epameinondas Leontidis

This paper is an introductory review of the problem of front propagation into unstable states. Our presentation is centered around the concept of the asymptotic linear spreading velocity v*, the asymptotic rate with which initially…

Soft Condensed Matter · Physics 2015-06-24 Wim van Saarloos

We consider diffusion processes on metric graphs with semipermeable sticky membranes in each vertex. We prove that the process is governed by a Feller semigroup and find its asymptotic behavior as diffusion's speed increases to infinity…

Probability · Mathematics 2022-01-25 Adam Gregosiewicz

Reaction-advection-diffusion equations, in periodic settings and with general type nonlinearities, admit a threshold known as the minimal speed of propagation. The minimal speed does not have an accessible formula when the nonlinearity is…

Analysis of PDEs · Mathematics 2020-01-17 Mohammad El Smaily , Chunhua Ou

Scaling and mechanism of the propagation speed of turbulent fronts in pipe flow with the Reynolds number has been a long-standing problem in the past decades. Here, we derive an explicit scaling law of the upstream front speed, which…

Fluid Dynamics · Physics 2023-11-13 Haoyang Wu , Baofang Song

We consider a diffusing particle, with diffusion constant D', moving in one dimension in an infinite sea of noninteracting mobile traps with diffusion constant D and density rho. We show that the asymptotic behavior of the survival…

Statistical Mechanics · Physics 2009-11-07 Alan J. Bray , Richard A. Blythe

This paper establishes the spectral stability in exponentially weighted spaces of smooth traveling monotone fronts for reaction diffusion equations of Fisher-KPP type with nonlinear degenerate diffusion coefficient. It is assumed that the…

Analysis of PDEs · Mathematics 2017-06-02 J. Francisco Leyva , Ramon G. Plaza

Score-based diffusion models, while achieving minimax optimality for sampling, are often hampered by slow sampling speeds due to the high computational burden of score function evaluations. Despite the recent remarkable empirical advances…

Machine Learning · Computer Science 2025-02-27 Gen Li , Changxiao Cai

Particle acceleration in relativistic shocks is studied analytically in the test-particle, small-angle scattering limit, for an arbitrary velocity-angle diffusion function D. Accurate analytic expressions for the spectral index s are…

Astrophysics · Physics 2008-11-26 Uri Keshet

The dynamics of horizontal plasma flows during the first hours of the emergence of active region magnetic flux in the solar photosphere have been analyzed using SOHO/MDI data. Four active regions emerging near the solar limb have been…

Solar and Stellar Astrophysics · Physics 2017-05-01 A. Khlystova

We study the existence of traveling wave solutions for a numerical counterpart of the KPP equation. We obtain the existence of monostable fronts for all super-critical speeds in the regime where the spatial step size is small. The key…

Numerical Analysis · Mathematics 2024-12-24 Louis Garénaux , Hermen Jan Hupkes

We propose a simple alternative proof of a famous result of Gallay regarding the nonlinear asymptotic stability of the critical front of the Fisher-KPP equation which shows that perturbations of the critical front decay algebraically with…

Analysis of PDEs · Mathematics 2018-09-14 Gregory Faye , Matt Holzer

In Part II of this series of papers, we consider an initial-boundary value problem for the Kolmogorov--Petrovskii--Piscounov (KPP) type equation with a discontinuous cut-off in the reaction function at concentration $u=u_c$. For fixed…

Analysis of PDEs · Mathematics 2020-09-08 A. D. O. Tisbury , D. J. Needham , A. Tzella

The concept of pulled fronts with a cutoff $\epsilon$ has been introduced to model the effects of discrete nature of the constituent particles on the asymptotic front speed in models with continuum variables (Pulled fronts are the fronts…

Statistical Mechanics · Physics 2009-11-07 Debabrata Panja , Wim van Saarloos

We consider Kolmogorov--Petrovskii--Piscounov (KPP) type models in the presence of a discontinuous cut-off in reaction rate at concentration $u=u_c$. In Part I we examine permanent form travelling wave solutions (a companion paper, Part II,…

Analysis of PDEs · Mathematics 2020-09-07 A D O Tisbury , D J Needham , A Tzella

We consider a Fisher-KPP-type equation, where both diffusion and nonlinear part are nonlocal, with anisotropic probability kernels. Under minimal conditions on the coefficients, we prove existence, uniqueness, and uniform space-time…

Analysis of PDEs · Mathematics 2015-09-22 Dmitri Finkelshtein , Yuri Kondratiev , Pasha Tkachov

Incompressibility is a fundamental condition in most fluid models. Accumulation of simulation errors violates it and causes volume loss. Past work suggested correction methods to battle it. These methods, however, are imperfect and in some…

Graphics · Computer Science 2026-01-21 Zohar Levi
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