Florian Kreten | Searcharxiv

arXiv2023

Convective stability of the critical waves of an FKPP growth process

We construct the traveling wave solutions of an FKPP growth process of two densities of particles, and prove that the critical traveling waves are locally stable in a space where the perturbations can grow exponentially at the back of the wave. The considered reaction-diffusion system was introduced by Hannezo et al. in the context of branching morphogenesis (Cell, 171(1):242-255.e27, 2017): active, branching particles accumulate inactive particles, which do not react. Thus, the system features a continuum of steady state solutions, complicating the analysis. We adopt a result by Faye and Holzer (J.Diff.Eq., 269(9):6559-6601, 2020) for proving the stability of the critical traveling waves, by modifying the semi-group estimates to a space with unbounded weights. The novelty is that we use a Feynman-Kac formula to get an exponential a-priori estimate for the left tail of the PDE, in the regime where the weight is unbounded.

math.AP↗

arXiv2022

Traveling waves of an FKPP-type model for self-organized growth

We consider a reaction-diffusion system of densities of two types of particles, introduced by Edouard Hannezo et al. in the context of branching morphogenesis. It is a simple model for a growth process: active, branching particles form the growing boundary layer of an otherwise static tissue, represented by inactive particles (Cell, 171(1):242-255.e27, 2017). The active particles diffuse, branch and become irreversibly inactive upon collision with a particle of arbitrary type. In absence of active particles, this system is in a steady state, without any a priori restriction on the amount of remaining inactive particles. Thus, while related to the well-studied FKPP-equation, this system features a game-changing continuum of steady state solutions, where each corresponds to a possible outcome of the growth process. However, simulations indicate that this system self-organizes: traveling fronts with fixed shape arise under a wide range of initial data. In the present work, we describe all positive and bounded traveling wave solutions, and obtain necessary and sufficient conditions for their existence. We find a surprisingly simple symmetry in the pairs of steady states which are joined via heteroclinic wave orbits. Our approach is constructive: we first prove the existence of almost constant solutions and then extend our results via a continuity argument along the continuum of limiting points.

math.AP↗