Thin fluid layers are common natural habitats for various species of aerobic bacteria. Collective behaviors in bacterial colonies caused by chemotaxis can form complex bioconvection patterns, which often work in favor of the colony’s survival and growth. The connection between the biology of bacterial aerotaxis and the physics of buoyancy effects caused by non-uniform suspension density is numerically investigated for a suspension of oxytactic bacteria placed in the Petri dish. The upper surface is free and open to the atmosphere, and through it oxygen diffuses into the suspension. Surface tension and dynamic contact line are incorporated into the mathematical and numerical models. A comparison has been made between dynamic free surface and fixed free surface models, and differences have been revealed. The parametric study in the case of dynamic free surface has been performed, and the non-linear dynamics of the phenomenon has been investigated. Resulting from upward aerotaxis and downward gravitational force, Rayleigh–Taylor-like instabilities develop between layers of different densities in the suspension. Bacterial plume patterns and their dynamics, such as sinking, merging, and birth of new plumes, characterize the phenomenon for particular intervals of dimensionless parameters. Accordingly, categorization of the phenomenon based on bacterial plume evolution has been made, and significant intervals of dimensionless parameters have been extracted.

中文翻译：

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具有自由表面的薄流体层中的细菌趋化性

薄流体层是各种需氧细菌的常见自然栖息地。由趋化性引起的细菌菌落中的集体行为可以形成复杂的生物对流模式，这通常有利于菌落的生存和生长。对于放置在培养皿中的催产细菌悬浮液，对细菌趋气性生物学与由非均匀悬浮密度引起的浮力效应物理学之间的联系进行了数值研究。上表面是自由的，对大气开放，氧气通过它扩散到悬浮液中。表面张力和动态接触线被纳入数学和数值模型。对动态自由表面模型和固定自由表面模型进行了比较，发现了差异。已经进行了动态自由表面情况下的参数研究，并研究了该现象的非线性动力学。由于向上的浮力和向下的重力，悬浮液中不同密度的层之间会产生类似瑞利-泰勒的不稳定性。细菌羽流模式及其动力学，例如下沉、合并和新羽流的诞生，表征了特定无量纲参数区间的现象。因此，基于细菌羽流进化的现象进行了分类，并提取了无量纲参数的重要区间。Rayleigh-Taylor 样不稳定性在悬浮液中不同密度的层之间发展。细菌羽流模式及其动力学，例如下沉、合并和新羽流的诞生，表征了特定无量纲参数区间的现象。因此，基于细菌羽流进化的现象进行了分类，并提取了无量纲参数的重要区间。Rayleigh-Taylor 样不稳定性在悬浮液中不同密度的层之间发展。细菌羽流模式及其动力学，例如下沉、合并和新羽流的诞生，表征了特定无量纲参数区间的现象。因此，基于细菌羽流进化的现象进行了分类，并提取了无量纲参数的重要区间。