Weak solutions for a bioconvection model related to Bacillus subtilis

TL;DR

This paper establishes the existence of global weak solutions for a complex bioconvection model involving Bacillus subtilis, analyzing different cases based on diffusion and dimension, and explores long-term dynamics and attractors.

Contribution

It provides the first existence results for weak solutions to a coupled Navier-Stokes-Keller-Segel system modeling Bacillus subtilis bioconvection, including new results even without growth terms.

Findings

Existence of global weak solutions in 2D and 3D.

Regularity and uniqueness in the whole plane case.

Analysis of long-time behaviour and attractors.

Abstract

We consider the initial-boundary value problem for the coupled Navier-Stokes-Keller-Segel-Fisher-Kolmogorov-Petrovskii-Piskunov system in two- and three-dimensional domains. The problem describes oxytaxis and growth of Bacillus subtilis in moving water. We prove existence of global weak solutions to the problem. We distinguish between two cases determined by the cell diffusion term and the space dimension, which are referred as the supercritical and subcritical ones. At the first case, the choice of the growth function enjoys wide range of possibilities: in particular, it can be zero. Our results are new even at the absence of the growth term. At the second case, the restrictions on the growth function are less relaxed: for instance, it cannot be zero but can be Fisher-like. In the case of linear cell diffusion, the solution is regular and unique provided the domain is the whole plane. In addition, we study the long-time behaviour of the problem, find dissipative estimates, and construct attractors.