Front structure and dynamics in dense colonies of motile bacteria: Role of active turbulence

TL;DR

This study investigates how active turbulence influences bacterial colony expansion, revealing that turbulence enhances front speed and causes crumpling, with differences observed across models and connections to passive scalar fronts.

Contribution

Introduces two minimalistic models and DNS simulations to explore the effects of turbulence on bacterial colony front dynamics and structure.

Findings

Turbulence increases colony front speed.

Turbulence causes front crumpling.

Differences observed between the two models.

Abstract

We study the spreading of a bacterial colony undergoing turbulent like collective motion. We present two minimalistic models to investigate the interplay between population growth and coherent structures arising from turbulence. Using Direct Numerical Simulation (DNS) of the proposed models we find that turbulence has two prominent effects on the spatial growth of the colony: (a) the front speed is enhanced, and (b) the front gets crumpled. Both these effects, which we highlight by using statistical tools, are markedly different in our two models. We also show that the crumpled front structure and the passive scalar fronts in random flows are related in certain regimes.