van der Linden Joost H, Tordesillas Antoinette, Narsilio Guillermo A
Department of Infrastructure Engineering, The University of Melbourne, Melbourne, Australia.
School of Mathematics and Statistics & School of Earth Sciences, The University of Melbourne, Melbourne, Australia.
Sci Rep. 2019 Dec 3;9(1):18231. doi: 10.1038/s41598-019-54699-6.
Existing definitions of where and why preferential flow in porous media occurs, or will occur, assume a priori knowledge of the fluid flow and do not fully account for the connectivity of available flow paths in the system. Here we propose a method for identifying preferential pathways through a flow network, given its topology and finite link capacities. Using data from a deforming granular medium, we show that the preferential pathways form a set of percolating pathways that is optimized for global transport of interstitial pore fluid in alignment with the applied pressure gradient. Two functional subgroups emerge. The primary subgroup comprises the main arterial paths that transmit the greatest flow through shortest possible routes. The secondary subgroup comprises inter- and intra-connecting bridges that connect the primary paths, provide alternative flow routes, and distribute flow through the system to maximize throughput. We examine the multiscale relationship between functionality and subgroup structure as the sample dilates in the lead up to the failure regime where the global volume then remains constant. Preferential flow pathways chain together large, well-connected pores, reminiscent of force chain structures that transmit the majority of the load in the solid grain phase.
关于多孔介质中优先流在何处以及为何发生，或将会发生的现有定义，假定了对流体流动的先验知识，并且没有充分考虑系统中可用流动路径的连通性。在此，我们提出一种方法，用于在已知流动网络拓扑结构和有限链路容量的情况下识别优先路径。利用来自变形颗粒介质的数据，我们表明优先路径形成了一组渗流路径，这些路径针对间隙孔隙流体的全局传输进行了优化，与施加的压力梯度保持一致。出现了两个功能子群。主要子群包括通过尽可能短的路径传输最大流量的主要动脉路径。次要子群包括连接主要路径的内部和相互连接桥，提供替代流动路径，并通过系统分配流量以最大化通量。我们研究了在接近破坏状态（此时总体积保持恒定）时样品膨胀过程中功能与子群结构之间的多尺度关系。优先流动路径将大的、连接良好的孔隙连接在一起，这让人联想到在固体颗粒相中传递大部分载荷的力链结构。
