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We introduce a novel numerical method for direct simulation of front propagation in the Fisher-KPP equation with a time-dependent parameter on an infinite domain. The method computes a time-dependent boundary condition that accurately…

Fluid Dynamics · Physics 2026-02-12 Troy Tsubota , Smridhi Mahajan , Adrian van Kan , Edgar Knobloch

We study in this note the Fisher-KPP equation where the Laplacian is replaced by the generator of a Feller semigroup with slowly decaying kernel, an important example being the fractional Laplacian. Contrary to what happens in the standard…

Analysis of PDEs · Mathematics 2009-05-11 Xavier Cabre , Jean-Michel Roquejoffre

We propose here a new model of accelerating fronts, consisting of one equation with non-local diffusion on a line, coupled via the boundary condition with a reaction-diffusion equation in the upper half-plane. The underlying biological…

Analysis of PDEs · Mathematics 2015-07-01 Henri Berestycki , Anne-Charline Coulon , Jean-Michel Roquejoffre , Luca Rossi

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…

Analysis of PDEs · Mathematics 2015-07-08 Fang Li , Xing Liang , Wenxian Shen

We provide an asymptotic analysis of a non-local Fisher-KPP type equation in periodic media and with a non-local stable operator of order $\alpha$ $\in$ (0, 2). We perform a long time-long range scaling in order to prove that the stable…

Analysis of PDEs · Mathematics 2018-12-14 Alexis Léculier

We provide an asymptotic analysis of a fractional Fisher-KPP type equation in periodic non-connected 1-dimensional media with Dirichlet conditions outside the domain. After demonstrating the existence and uniqueness of a non-trivial bounded…

Analysis of PDEs · Mathematics 2019-10-28 Alexis Léculier , Sepideh Mirrahimi , Jean-Michel Roquejoffre

The hexagonal structure is ubiquitous in nature. The propagation phenomena occurring in a media with a hexagonal structure remain to be explored. One way of exploring this question is to formulate lattice dynamical systems and analyze the…

Dynamical Systems · Mathematics 2025-12-01 Jian Fang , Yifei Li , Yijun Lou , Jian Wang

We study the large time asymptotics of a solution of the Fisher-KPP reaction-diffusion equation, with an initial condition that is a compact perturbation of a step function. A well-known result of Bramson states that, in the reference frame…

Analysis of PDEs · Mathematics 2016-06-20 James Nolen , Jean-Michel Roquejoffre , Lenya Ryzhik

This paper is concerned with asymptotic persistence, extinction and spreading properties for non-cooperative Fisher-KPP systems with space-time periodic coefficients. Results are formulated in terms of a family of generalized principal…

Analysis of PDEs · Mathematics 2025-01-14 Léo Girardin

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

The propagation of fronts in the Fisher-Kolmogorov equation with spatially varying diffusion coefficients is studied. Using coordinate changes, WKB approximations, and multiple scales analysis, we provide an analytic framework that…

Analysis of PDEs · Mathematics 2012-12-24 Christopher W. Curtis , David M. Bortz

We consider Fisher-KPP-type reaction-diffusion equations with spatially inhomogeneous reaction rates. We show that a sufficiently strong localized inhomogeneity may prevent existence of transition-front-type global in time solutions while…

Analysis of PDEs · Mathematics 2015-05-20 James Nolen , Jean-Michel Roquejoffre , Lenya Ryzhik , Andrej Zlatos

We consider a reaction-diffusion-advection equation of the form: $u_t=u_{xx}-\beta(t)u_x+f(t,u)$ for $x\in (g(t),h(t))$, where $\beta(t)$ is a $T$-periodic function representing the intensity of the advection, $f(t,u)$ is a Fisher-KPP type…

Analysis of PDEs · Mathematics 2016-04-05 Ningkui Sun , Bendong Lou , Maolin Zhou

We prove existence of and construct transition fronts for a class of reaction- diffusion equations with spatially inhomogeneous Fisher-KPP type reactions and non-local diffusion. Our approach is based on finding these solutions as…

Analysis of PDEs · Mathematics 2014-10-29 Tau Shean Lim , Andrej Zlatos

We consider the Fisher-KPP equation with a non-local interaction term. Hamel and Ryzhik showed that in solutions of this equation, the front location at a large time $t$ is $\sqrt 2 t +o(t)$. We study the asymptotics of the second order…

Probability · Mathematics 2017-08-29 Sarah Penington

We study the Fisher-KPP equation where the Laplacian is replaced by the generator of a Feller semigroup with power decaying kernel, an important example being the fractional Laplacian. In contrast with the case of the stan- dard Laplacian…

Analysis of PDEs · Mathematics 2015-06-04 Xavier Cabre , Jean-Michel Roquejoffre

We propose a novel method for establishing the convergence rates of solutions to reaction-diffusion equations to traveling waves. The analysis is based on the study of the traveling wave shape defect function introduced in [2]. It turns out…

Analysis of PDEs · Mathematics 2023-07-20 Jing An , Christopher Henderson , Lenya Ryzhik

The problem of diffusion in a time-dependent (and generally inhomogeneous) external field is considered on the basis of a generalized master equation with two times, introduced in [1,2]. We consider the case of the quasi Fokker-Planck…

Statistical Mechanics · Physics 2015-05-18 S. A. Trigger , G. J. F. van Heijst , O. F. Petrov , P. P. J. M. Schram

We present several families of nonlinear reaction diffusion equations with variable coefficients including Fisher-KPP and Burgers type equations. Special exact solutions such as traveling wave, rational, triangular wave and N-wave type…

Mathematical Physics · Physics 2017-10-25 E. Pereira , E. Suazo , J. Trespalacios

We study the existence of stationary solutions for a nonlocal version of the Fisher-Kolmogorov-Petrovskii-Piscounov (FKPP) equation. The main motivation is a recent study by Berestycki et {al.} [Nonlinearity 22 (2009), {pp.}~2813--2844]…

Analysis of PDEs · Mathematics 2015-03-06 Franz Achleitner , Christian Kuehn