标题： 芯片上的土壤颗粒动力学：流化启动的深入研究 显示英文标题

标题： Soil granular dynamics on-a-chip: fluidization inception under scrutiny

摘要： 预测快速和较慢的土壤演化仍然是一个科学挑战。 这个过程涉及无序颗粒物质和密集悬浮液动力学中尚不明确的方面。 本研究介绍了一种关于小规模芯片结构的新二维实验；这使得在摩擦力超过粘附力和热力的条件下，并在施加流体流动的情况下，观察大颗粒沉积床的粒子尺度变形成为可能。 实验是在跨越颗粒再悬浮准则的条件下进行的，颗粒运动被检测并分析。 空隙尺寸分布和颗粒轨迹统计为接近流态化条件的沉积动力学提供了见解。 具体而言，在流速显著低于不稳定增长准则的情况下，观察到颗粒重新排列和床层净压缩。 超过某个阈值后，床层中会形成一个大的垂直通道。 在可能发生通道化的流速范围内，观察到了压缩和膨胀床情况的共存。 该研究的结果增强了我们对沉积床缓慢动力学和最终快速失稳建模的能力。 微流控芯片土壤研究开辟了新的研究途径，包括溶解-沉淀、细颗粒物运输或微生物游泳和种群增长等，这些可能依赖于多孔介质本身的力学特性。 显示英文摘要

摘要： Predicting rapid and slower soil evolution remains a scientific challenge. This process involves poorly understood aspects of disordered granular matter and dense suspension dynamics. This study presents a novel two-dimensional experiment on a small-scale chip structure; this allows the observation of the deformation at the particle scale of a large-grained sediment bed, under conditions where friction dominate over cohesive and thermal forces, and with an imposed fluid flow. Experiments are performed at conditions which span the particle resuspension criterion, and particle motion is detected and analyzed. The void size population and statistics of particle trajectories bring insight to the sediment dynamics near fluidization conditions. Specifically, particle rearrangement and net bed compaction are observed at flow rates significantly below the criterion for instability growth. Above a threshold, a large vertical channel through the bed forms. In the range of flow rates where channelization can occur, the coexistence of compacting and dilating bed scenarios is observed. The results of the study enhance our capacity for modeling of both slow dynamics and eventual rapid destabilization of sediment beds. Microfluidics channel soil-on-a-chip studies open avenues to new investigations including dissolution-precipitation, fine particles transport, or micro-organisms swimming and population growth, which may depend on mechanics of the porous media itself.