Topological inversions in coalescing granular media control fluid-flow regimes.
Topological inversions in coalescing granular media control fluid-flow regimes.
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聚结颗粒介质中的拓扑反转控制流体流动状态。
DOI：
10.1103/physreve.96.033113
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
Donald Bruce Dingwell
中科院分区：
文献类型：
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作者：
F. Wadsworth;J. Vasseur;E. Llewellin;K. Dobson;M. Colombier;Felix W. von Aulock;J. L. Fife;S. Wiesmaier;K. Hess;B. Scheu;Y. Lavallée;Donald Bruce Dingwell
在许多自然和工业场景中，粘性液滴的烧结或凝聚是必不可少的过程。目前烧结动力学的物理模型由于缺乏对微观结构几何演化的明确描述而受到限制。在这里，我们使用高速时间分辨x射线断层扫描成像粘性液滴烧结系统的演化几何形状，并使用晶格玻尔兹曼模拟爬行流体通过重建的孔隙空间来确定其渗透率。我们确定并表征了拓扑反转，从连续间隙气体中的球形液滴到连续液体中的孤立气泡。我们发现拓扑反演与渗透率-孔隙度行为的转变有关，从高孔隙度的Stokes渗透率到低孔隙度的渗流理论。我们利用这些发现来构建一个统一的物理描述，以调和以前不相容的模型在烧结过程中孔隙度和渗透率的演变。
Sintering-or coalescence-of viscous droplets is an essential process in many natural and industrial scenarios. Current physical models of the dynamics of sintering are limited by the lack of an explicit account of the evolution of microstructural geometry. Here, we use high-speed time-resolved x-ray tomography to image the evolving geometry of a sintering system of viscous droplets, and use lattice Boltzmann simulations of creeping fluid flow through the reconstructed pore space to determine its permeability. We identify and characterize a topological inversion, from spherical droplets in a continuous interstitial gas, to isolated bubbles in a continuous liquid. We find that the topological inversion is associated with a transition in permeability-porosity behavior, from Stokes permeability at high porosity, to percolation theory at low porosity. We use these findings to construct a unified physical description that reconciles previously incompatible models for the evolution of porosity and permeability during sintering.