Tierra Giordano, Pavissich Juan P, Nerenberg Robert, Xu Zhiliang, Alber Mark S
Mathematical Institute, Faculty of Mathematics and Physics, Charles University, 186 75 Prague 8, Czech Republic Department of Applied and Computational Mathematics and Statistics University of Notre Dame, Notre Dame, IN 46556, USA.
Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN 46556, USA Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez, Santiago, Chile.
J R Soc Interface. 2015 May 6;12(106). doi: 10.1098/rsif.2015.0045.
A novel biofilm model is described which systemically couples bacteria, extracellular polymeric substances (EPS) and solvent phases in biofilm. This enables the study of contributions of rheology of individual phases to deformation of biofilm in response to fluid flow as well as interactions between different phases. The model, which is based on first and second laws of thermodynamics, is derived using an energetic variational approach and phase-field method. Phase-field coupling is used to model structural changes of a biofilm. A newly developed unconditionally energy-stable numerical splitting scheme is implemented for computing the numerical solution of the model efficiently. Model simulations predict biofilm cohesive failure for the flow velocity between [Formula: see text] and [Formula: see text] m s(-1) which is consistent with experiments. Simulations predict biofilm deformation resulting in the formation of streamers for EPS exhibiting a viscous-dominated mechanical response and the viscosity of EPS being less than [Formula: see text]. Higher EPS viscosity provides biofilm with greater resistance to deformation and to removal by the flow. Moreover, simulations show that higher EPS elasticity yields the formation of streamers with complex geometries that are more prone to detachment. These model predictions are shown to be in qualitative agreement with experimental observations.
描述了一种新型生物膜模型，该模型系统地耦合了生物膜中的细菌、胞外聚合物（EPS）和溶剂相。这使得能够研究各相流变学对生物膜在流体流动作用下变形的贡献以及不同相之间的相互作用。该模型基于热力学第一和第二定律，采用能量变分方法和相场方法推导得出。相场耦合用于模拟生物膜的结构变化。为有效计算模型的数值解，实施了一种新开发的无条件能量稳定数值分裂格式。模型模拟预测，在流速为[公式：见原文]至[公式：见原文]米每秒之间时生物膜会发生内聚性破坏，这与实验结果一致。模拟预测，对于表现出粘性主导力学响应且EPS粘度小于[公式：见原文]的EPS，生物膜变形会导致形成拖尾。较高的EPS粘度使生物膜具有更大的抗变形能力和抗流动去除能力。此外，模拟表明，较高的EPS弹性会导致形成具有更复杂几何形状且更易脱落的拖尾。这些模型预测结果与实验观察结果在定性上一致。
