标题： 渗透性非均质性和位移粘土悬浮液的整体线性弹性决定了Hele-Shaw实验中的界面图案形态 显示英文标题

标题： Permeability heterogeneity and bulk linear elasticity of displaced clay suspensions determine interfacial pattern morphologies in Hele-Shaw experiments

摘要： 当一种粘度较低的牛顿流体在受限空间中驱替一种老化的水基粘土悬浮液时，由于主要的粘性不稳定性，会呈现出丰富的界面图案。 在本研究中，我们通过加入添加剂来控制粘土悬浮液的力学性能，并研究了这些悬浮液在Hele-Shaw细胞中被水径向驱替时产生的界面不稳定性。 当粘土的弹性较低时，界面动力学表现出非线性粘性指进在异质介质中的特征。 通过调节延缓粘土老化的添加剂的性质和含量，我们揭示了两种新的传播机制：模式生长\textit{通过}钻刺和之字形指进传播。 这些模式迄今为止在胶体系统实验中从未被观察到。 对于中等粘土弹性，我们在此证明剪切稀化引起的流动各向异性会导致具有主导侧枝的树突状结构的形成。 随着盐类的加入导致粘土弹性增加，产生裂纹所需的能量小于系统整体屈服所需的能量。 这种情形以粘弹性的裂纹出现为特征。 我们的工作表明，加入添加剂是一种有效策略，可以操控由可混溶牛顿流体在受限空间中驱替粘土时界面不稳定的起始和生长。 显示英文摘要

摘要： When a less viscous Newtonian fluid displaces an aging aqueous clay suspension in a confined space, a rich array of interfacial patterns emerges due to a predominantly viscous instability. In the present work, we controlled the mechanical properties of clay suspensions by incorporating additives and studied the interfacial instabilities that resulted when these suspensions were radially displaced by water in a Hele-Shaw cell. When the elasticity of clay was low, the interfacial dynamics exhibited features of nonlinear viscous fingering in heterogeneous media. By tuning the nature and content of additives that delay clay aging, we uncovered two novel propagation mechanisms: pattern growth \textit{via} skewering and zig-zag finger propagation. These patterns have hitherto never been observed in experiments with colloidal systems. For moderate clay elasticities, we demonstrate here that shear-thinning-induced flow anisotropy leads to the formation of dendrites with dominant side branches. As clay elasticity increases due to the incorporation of salts, the energy required to create fractures becomes smaller than that for system-wide yielding. This scenario is characterized by the emergence of viscoelastic fractures. Our work demonstrates that incorporating additives is an effective strategy to manipulate the onset and growth of interfacial instabilities during the confined displacement of clay by miscible Newtonian fluids.