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We study a Fisher-KPP equation with spatially periodic diffusion and reaction terms. We identify a class of periodic media for which the equation admits an explicit, closed-form solution. Through a nonlinear change of variables, the problem…

Analysis of PDEs · Mathematics 2025-12-09 Lionel Roques

The famous Fisher-KPP reaction-diffusion model combines linear diffusion with the typical KPP reaction term, and appears in a number of relevant applications in biology and chemistry. It is remarkable as a mathematical model since it…

Analysis of PDEs · Mathematics 2016-02-19 Alessandro Audrito , Juan Luis Vázquez

In this paper, we consider a Fisher-KPP equation with an advection term and two free boundaries, which models the behavior of an invasive species in one dimension space. When spreading happens (that is, the solution converges to a positive…

Analysis of PDEs · Mathematics 2013-02-27 Hong Gu , Zhigui Lin , Bendong Lou

In this paper we consider a reaction-diffusion equation of Fisher-KPP type inside an infinite cylindrical domain in $\mathbb{R}^{N+1}$, coupled with a reaction-diffusion equation on the boundary of the domain, where potentially fast…

Analysis of PDEs · Mathematics 2015-04-21 Luca Rossi , Andrea Tellini , Enrico Valdinoci

We establish a new property of Fisher-KPP type propagation in a plane, in the presence of a line with fast diffusion. We prove that the line enhances the asymptotic speed of propagation in a cone of directions. Past the critical angle given…

Analysis of PDEs · Mathematics 2015-01-09 Henri Berestycki , Jean-Michel Roquejoffre , Luca Rossi

This paper investigates the asymptotic behavior of the solutions of the Fisher-KPP equation in a heterogeneous medium, $$\partial_t u = \partial_{xx} u + f(x,u),$$ associated with a compactly supported initial datum. A typical nonlinearity…

Analysis of PDEs · Mathematics 2015-06-03 Jimmy Garnier , Thomas Giletti , Gregoire Nadin

We determine the asymptotic spreading speed of the solutions of a Fisher-KPP reaction-diffusion equation, starting from compactly supported initial data, when the diffusion coefficient is a fixed bounded monotone profile that is shifted at…

Analysis of PDEs · Mathematics 2021-03-30 Grégory Faye , Thomas Giletti , Matt Holzer

This paper is concerned with spreading properties of space-time heterogeneous Fisher--KPP equations in one space dimension. We focus on the case of everywhere favorable environment with three different zones, a left half-line with slow or…

Analysis of PDEs · Mathematics 2025-11-07 Thomas Giletti , Léo Girardin , Hiroshi Matano

This paper is devoted to studying propagation phenomena in integro-differential equations with a weakly degenerate non-linearity. The reaction term can be seen as an intermediate between the classical logistic (or Fisher-KPP) non-linearity…

Analysis of PDEs · Mathematics 2024-12-10 Emeric Bouin , Jérôme Coville , Xi Zhang

We take interest in a reaction-diffusion system which has been recently proposed [11] as a model for the effect of a road on propagation phenomena arising in epidemiology and ecology. This system consists in coupling a classical Fisher-KPP…

Analysis of PDEs · Mathematics 2015-09-08 Thomas Giletti , Léonard Monsaingeon , Maolin Zhou

This paper focuses on propagation phenomena in reaction-diffusion equations with a weaklymonostable nonlinearity. The reaction term can be seen as an intermediate between the classicallogistic one (or Fisher-KPP) and the standard weak Allee…

Analysis of PDEs · Mathematics 2023-12-18 Emeric Bouin , Jérôme Coville , Xi Zhang

Spatially periodic reaction-diffusion equations typically admit pulsating waves which describe the transition from one steady state to another. Due to the heterogeneity, in general such an equation is not invariant by rotation and therefore…

Analysis of PDEs · Mathematics 2020-06-11 Weiwei Ding , Thomas Giletti

We consider a class of reaction-diffusion equations of Fisher-KPP type in which the nonlinearity (reaction term) $f$ is merely $C^1$ at $u=0$ due to a logarithmic competition term. We first derive the asymptotic behavior of (minimal speed)…

Analysis of PDEs · Mathematics 2020-09-03 Emeric Bouin , Christopher Henderson

We perform the analysis of a hyperbolic model which is the analog of the Fisher-KPP equation. This model accounts for particles that move at maximal speed $\epsilon^{-1}$ ($\epsilon\textgreater{}0$), and proliferate according to a reaction…

Analysis of PDEs · Mathematics 2016-11-22 Emeric Bouin , Vincent Calvez , Grégoire Nadin

We focus on the persistence and spreading properties for a heterogeneous Fisher-KPP equation with advection. After reviewing the different notions of persistence and spreading speeds, we focus on the effect of the direction of the advection…

Analysis of PDEs · Mathematics 2025-03-31 Nathanaël Boutillon , François Hamel , Lionel Roques

We investigate the influence of steady periodic flows on the propagation of chemical fronts in an infinite channel domain. We focus on the sharp front arising in Fisher--Kolmogorov--Petrovskii--Piskunov (FKPP) type models in the limit of…

Fluid Dynamics · Physics 2018-12-12 Alexandra Tzella , Jacques Vanneste

We report on recent progress in the study of nonlinear diffusion equations involving nonlocal, long-range diffusion effects. Our main concern is the so-called fractional porous medium equation, $\partial_t u +(-\Delta)^{s}(u^m)=0$, and some…

Analysis of PDEs · Mathematics 2014-01-16 Juan Luis Vázquez

In Cao, Du, Li and Li [8], a nonlocal diffusion model with free boundaries extending the local diffusion model of Du and Lin [12] was introduced and studied. For Fisher-KPP type nonlinearities, its long-time dynamical behaviour is shown to…

Analysis of PDEs · Mathematics 2020-01-28 Yihong Du , Fang Li , Maolin Zhou

We propose here a new model to describe biological invasions in the plane when a strong diffusion takes place on a line. We establish the main properties of the system, and also derive the asymptotic speed of spreading in the direction of…

Analysis of PDEs · Mathematics 2012-10-17 Henri Berestycki , Jean-Michel Roquejoffre , Luca Rossi

We investigate in this paper propagation phenomena for the heterogeneous reaction-diffusion equation $\partial_t u -\Delta u = f(t,u)$, $x\in R^N$, $t\in\R$, where f=f(t,u) is a KPP monostable nonlinearity which depends in a general way on…

Analysis of PDEs · Mathematics 2011-05-03 Grégoire Nadin , Luca Rossi