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We consider here a model of accelerating fronts, introduced in [2], consisting of one equation with nonlocal diffusion on a line, coupled via the boundary condition with a reaction-diffusion equation of the Fisher-KPP type in the upper…

Analysis of PDEs · Mathematics 2019-11-11 Anne-Charline Chalmin , Jean-Michel Roquejoffre

This paper is devoted to the study of travelling fronts of reaction-diffusion equations with periodic advection in the whole plane $\mathbb R^2$. We are interested in curved fronts satisfying some "conical" conditions at infinity. We prove…

Analysis of PDEs · Mathematics 2014-05-21 Mohammad El Smaily , Francois Hamel , Rui Huang

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

We consider a reaction-diffusion equation with a nonlinear term of the Fisher-KPP type, depending on time $t$ and admitting two limits as $t\to\pm\infty$. We derive the set of admissible asymptotic past and future speeds of transition…

Analysis of PDEs · Mathematics 2014-11-24 Francois Hamel , Luca Rossi

We consider the effect of a shear flow which has, without loss of generality, a zero mean flow rate, on a Kolmogorov--Petrovskii--Piscounov (KPP) type model in the presence of a discontinuous cut-off at concentration $u = u_c$. Its…

Analysis of PDEs · Mathematics 2024-06-25 D. J. Needham , A. Tzella

We establish the variational principle of Kolmogorov-Petrovsky-Piskunov (KPP) front speeds in temporally random shear flows inside an infinite cylinder, under suitable assumptions of the shear field. A key quantity in the variational…

Analysis of PDEs · Mathematics 2016-09-07 James Nolen , Jack Xin

Depending on their mechanism of self-propulsion, active particles can exhibit a time-dependent, often periodic, propulsion velocity. The precise propulsion velocity profile determines their mean square displacement and their effective…

Soft Condensed Matter · Physics 2024-05-06 Arnau Jurado Romero , Carles Calero , Rossend Rey

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 prove via counterexamples that adding an advection term of the form Shear flow (whose streamlines are parallel to the direction of propagation) to a reaction-diffusion equation will be an enough heterogeneity to spoil the…

Analysis of PDEs · Mathematics 2013-07-30 Mohammad El Smaily

This paper is concerned with some nonlinear propagation phenomena for reaction-advection-diffusion equations in a periodic framework. It deals with travelling wave solutions of the equation $$u_t =\nabla\cdot(A(z)\nabla u) +q(z)\cdot\nabla…

Analysis of PDEs · Mathematics 2011-04-15 Mohammad El Smaily

We consider in this paper a reaction-diffusion system in presence of a flow and under a KPP hypothesis. While the case of a single-equation has been extensively studied since the pioneering Kolmogorov-Petrovski-Piskunov paper, the study of…

Analysis of PDEs · Mathematics 2015-05-18 Thomas Giletti

We study the asymptotics of front speeds of the reaction-diffusion equations with Kolmogorov-Petrovsky-Piskunov (KPP) nonlinearity and zero mean stationary ergodic Gaussian shear advection on the entire plane. By exploiting connections of…

Mathematical Physics · Physics 2007-05-23 J. Xin

We study numerically the evolution of one-dimensional FKPP fronts initiated from steep initial conditions in the presence of a quenched random growth rate. Compared to both the homogeneous case (with velocity $v_0$) and deterministic…

Disordered Systems and Neural Networks · Physics 2026-05-15 Ulysse Marquis , Henri Berestycki , Marc Barthelemy

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 investigate the large-scale transport properties of quasi-neutrally-buoyant inertial particles carried by incompressible zero-mean periodic or steady ergodic flows. We show how to compute large-scale indicators such as the…

The Fisher-KPP model, and generalisations thereof, is a simple reaction-diffusion models of biological invasion that assumes individuals in the population undergo linear diffusion with diffusivity $D$, and logistic proliferation with rate…

Pattern Formation and Solitons · Physics 2022-01-25 Maud El-Hachem , Scott W McCue , Matthew J Simpson

In this paper, we study the propagation speeds of reaction-diffusion-advection (RDA) fronts in time-periodic cellular and chaotic flows with Kolmogorov-Petrovsky-Piskunov (KPP) nonlinearity. We first apply the variational principle to…

Numerical Analysis · Mathematics 2021-05-18 Junlong Lyu , Zhongjian Wang , Jack Xin , Zhiwen Zhang

In this paper, some properties of the minimal speeds of pulsating Fisher-KPP fronts in periodic environments are established. The limit of the speeds at the homogenization limit is proved rigorously. Near this limit, generically, the fronts…

Analysis of PDEs · Mathematics 2014-05-21 Mohammad El Smaily , Francois Hamel , Lionel Roques

This article is concerned with the rigorous validation of anomalous spreading speeds in a system of coupled Fisher-KPP equations of cooperative type. Anomalous spreading refers to a scenario wherein the coupling of two equations leads to…

Analysis of PDEs · Mathematics 2015-07-22 Matt Holzer

In this paper, we treat the Fisher-KPP equation with a Caputo-type time fractional derivative and discuss the propagation speed of the solution. The equation is a mathematical model that describes the processes of sub-diffusion,…

Analysis of PDEs · Mathematics 2026-01-21 Hiroshi Ishii