标题： 浓缩颗粒悬浮液的动态润湿 显示英文标题

标题： Dynamic wetting of concentrated granular suspensions

摘要： 许多材料，如用于绘画和3D打印等应用的涂料和油墨，都是浓缩的颗粒悬浮液。 在这样的系统中，接触线动力学和悬浮液的内部结构通过剪切速率依赖的粘度和内部结构重排相互作用。 在移动接触线附近，剪切速率急剧增加，深刻影响密集悬浮液的非牛顿流变特性。 当颗粒彼此接近时，摩擦接触变得显著，形成承载力的接触网络。 虽然水动力学解可以描述稀释悬浮液，但在密集悬浮液中的前进接触线附近的适用性仍不清楚。 本研究通过系统地改变粒子间相互作用来探索这种适用性。 我们使用两种折射率匹配的介质中的二氧化硅悬浮液：(i) 水中的2,$2^{\prime}$-硫代二乙醇（弱相互作用）和(ii) 水中的硫氰酸钠溶液（强相互作用）。 这两种样品在流变响应上有显著差异。 我们使用散光粒子追踪测速技术（APTV），精确跟踪悬浮液中示踪粒子的三维运动。 为了观察液滴在长行程距离上的行为，我们采用了一种由固定液滴和移动基底组成的配置。 我们观察到不同的行为，这取决于粒子相互作用和由此产生的悬浮液流变学。 粒子相互作用越显著，即非牛顿效应越明显，测量的流动剖面与流体力学方程的牛顿解差异越大。 在粘性悬浮液的情况下，观察到明显的非牛顿行为偏差。 相反，屈服应力悬浮液在基底上表现出塞流，而牛顿类似行为仅限于靠近基底的屈服区域。 显示英文摘要

摘要： Many materials, such as paints and inks used in applications like painting and 3D printing, are concentrated granular suspensions. In such systems, the contact line dynamics and the internal structure of the suspension interact through shear-rate dependent viscosity and internal structural rearrangements. The shear rate increases sharply near moving contact lines, profoundly influencing the non-Newtonian rheology of dense suspensions. Frictional contacts become significant as particles approach each other, forming force-carrying networks of contacts. While hydrodynamic solutions can describe dilute suspensions, their applicability near advancing contact lines in dense suspensions remains unclear. This study explores such applicability by systematically varying inter-particle interactions. We use silica suspensions in two refractive-index matched media: (i) aqueous 2,$2^{\prime}$-thiodiethanol (weak interactions) and (ii) aqueous sodium thiocyanate solution (strong interactions). The two samples vary substantially in their rheological response. Using astigmatism particle tracking velocimetry (APTV), we precisely track the 3D motion of tracer particles within the suspension. To observe the drop over a long travel distance, we use a configuration consisting of a pinned droplet on a moving substrate. We observe distinct behaviours depending on particle interactions and the resulting suspension rheology. The more the particle interactions play a role, i.e., the more pronounced the non-Newtonian effects, the stronger the measured flow profiles differ from the Newtonian solution to the hydrodynamic equations. In case of the viscous suspension, a notable deviation from Newtonian behaviour is observed. Conversely, the yield-stress suspension exhibits plug flow over the substrate, with Newtonian-like behaviour restricted to the yielded region near the substrate.