Spectral instability of small-amplitude periodic waves for hyperbolic non-Fickian diffusion advection models with logistic source

¹ Instituto de Investigaciones en Matemáticas Aplicadas y en Sistemas, Universidad Nacional Autónoma de México, Circuito Escolar s/n, Ciudad Universitaria, C.P. 04510, Cd. de México, Mexico
² Colegio de Ciencias y Humanidades, Universidad Nacional Autónoma de México, Prol. Periférico Oriente s/n Esq. Sur 24, Col. Agricola Oriental, C.P. 08500, Cd. de México, Mexico

^* Corresponding author: plaza@mym.iimas.unam.mx

Received: 10 February 2022
Accepted: 18 May 2022

Abstract

A hyperbolic model for diffusion, nonlfnear transport (or advection) and production of a scalar quantity, is considered. The model is based on a constitutive law of Cattaneo-Maxwell type expressing non-Fickian diffusion by means of a relaxation time relation. The production or source term is assumed to be of logistic type. This paper studies the existence and spectral stability properties of spatially periodic traveling wave solutions to this system. It is shown that a family of subcharacteristic periodic waves emerges from a local Hopf bifurcation around a critical value of the wave speed. These waves have bounded fundamental period and small-amplitude. In addition, it is shown that these waves are spectrally unstable as solutions to the hyperbolic system. For that purpose, it is proved that the Floquet spectrum of the linearized operator around a wave can be approximated by a linear operator whose point spectrum intersects the unstable half plane of complex numbers with positive real part.