The functioning of natural and engineered porous media, like soils and filters, depends in many cases on the interplay between biochemical processes and hydrodynamics. In such complex environments, microorganisms often form surface-attached communities known as biofilms. Biofilms can take the shape of clusters, which alter the distribution of fluid flow velocities within the porous medium, subsequently influencing biofilm growth. Despite numerous experimental and numerical efforts, the control of the biofilm clustering process and the resulting heterogeneity in biofilm permeability is not well understood, limiting our predictive abilities for biofilm-porous medium systems. Here, we use a quasi-2D experimental model of a porous medium to characterize biofilm growth dynamics for different pore sizes and flow rates. We present a method to obtain the time-resolved biofilm permeability field from experimental images and use the obtained permeability field to compute the flow field through a numerical model. We observe a biofilm cluster size distribution characterized by a spectrum slope evolving in time between −2 and −1, a fundamental measure that can be used to create spatio-temporal distributions of biofilm clusters for upscaled models. We find a previously undescribed biofilm permeability distribution, which can be used to stochastically generate permeability fields within biofilms. An increase in velocity variance for a decrease in physical heterogeneity shows that the bioclogged porous medium behaves differently than expected from studies on heterogeneity in abiotic porous media.

中文翻译：

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多孔介质中生物膜的形态发生和流体动力学控制

天然和工程多孔介质（如土壤和过滤器）的功能在许多情况下取决于生化过程和流体动力学之间的相互作用。在如此复杂的环境中，微生物通常会形成称为生物膜的表面附着群落。生物膜可以呈簇状，改变多孔介质内流体流速的分布，进而影响生物膜的生长。尽管进行了大量的实验和数值研究，但生物膜聚类过程的控制和由此产生的生物膜渗透性异质性尚不清楚，这限制了我们对生物膜-多孔介质系统的预测能力。在这里，我们使用准-2D 多孔介质实验模型，用于表征不同孔径和流速的生物膜生长动力学。我们提出了一种从实验图像中获取时间分辨生物膜渗透场的方法，并使用获得的渗透场通过数值模型计算流场。我们观察到生物膜簇大小分布的特征是光谱斜率在 -2 和 -1 之间随时间变化，这是一种基本度量，可用于为放大模型创建生物膜簇的时空分布。我们发现以前未描述的生物膜渗透性分布，可用于随机生成生物膜内的渗透性场。