Collaborative Research: Experimental and Numerical Characterization of Thin Films in Three-Dimensional Porous Media

0610108/0610003 Wildenschild/Schaap现有的多孔域中薄膜特性的分析通常建立在二维或准三维几何简单孔结构上，而没有明确地适应第三维中的孔连通性。为了弥合颗粒多孔介质中孔隙尺度薄膜特性的二维和三维实验分析之间的差距，以及三维数值和实验分析之间的差距，需要进行更深入的数值和实验研究。目的是将实验和数值分析相结合，以便更好地理解由任意粗糙集组成的三维多孔介质中的薄膜特性和热力学。在这个为期一年的扩展计划中，我们的目标是开发一个基于自由能的多相格子玻尔兹曼模型（可以处理具有高密度对比度的流体，并实现可靠的固体-流体相互作用）。为了获得模型验证的数据，我们将测量与破碎的火山凝灰岩中的薄膜形成和分布相关的薄膜特性。这包括成像水分布，因为它们的进展，从吸附膜毛细管举行的水与increasingvapor pressure。根据这些图像，可以估计毛细冷凝发生的临界分离距离。薄膜特性将首先bemeasured在几何简单的二维流动通道，使用延时数码显微镜，随后使用计算机微断层扫描（CMT）在破碎的凝灰岩样品更复杂的三维系统。从CMT图像中我们将确定毛细管凝聚区的位置和范围，以用于验证新的模型开发。一旦模型使用二维实验数据进行验证，模型将用于模拟具有水力连接的任意孔隙几何形状的三维天然多孔介质中的薄膜形成和分布。数值模拟结果的几何形状和范围的capillarycondensed区将进行比较的显微层析成像数据。然后，数值模型将用于绘制无法通过实验测量的变量的空间分布，例如流体密度、薄膜中的蒸汽压、界面宽度和三维曲率，以随后计算界面能、表面张力、化学势和分离压力。我们希望，从拟议的研究结果可能有重要的影响，在不同的领域，过程相关的低饱和度这些研究成果在以下领域具有重要意义：干旱地区灌溉和水管理、包气带污染物和胶体颗粒的归宿和迁移、非常干燥气候下的核废料处置、提高石油采收率以及行星科学。此外，该项目还为本科生和研究生以及博士后提供培训。

0610108/0610003Wildenschild/Schaap Existing analyses on thin film characteristics in porous domains are often built on two- orquasi-three dimensional geometrically simple pore structures without explicitlyaccommodating pore connectivity in the third dimension. More in-depth numerical andexperimental studies are needed to bridge the gap between two- and three dimensionalexperimental analyses as well as the gap between three-dimensional numerical andexperimental analyses of pore-scale thin-film characteristics in granular porous media.Hence, the proposed research, which builds on our ongoing pore-scale interfacialresearch, aims at integrating experimental and numerical analyses for betterunderstanding of thin film characteristics and thermodynamics in three-dimensionalporous media consisting of interconnected arbitrary rough-walled pore geometries.In this 1-year extension proposal, we aim to develop a thermodynamically soundfree-energy-based multiphase lattice-Boltzmann model (that can handle fluids with highdensitycontrasts and implements thermodynamically-sound solid-fluid interactions). Toobtain data for model verification, we will measure thin film characteristics related tofilm formation and distribution in a crushed volcanic tuff. This includes imaging waterdistributions as they progress from adsorbed films to capillary held water with increasingvapor pressure. Based on the images it is possible to estimate the critical separationdistance at which capillary condensation takes place. The film characteristics will first bemeasured in geometrically simple two-dimensional flow channels using time-lapse digitalmicroscopy, and subsequently using computerized microtomography (CMT) for morecomplex three-dimensional systems in crushed tuff samples. From the CMT images wewill determine the location and the extent of the capillary condensed regions to be used tovalidate new model developments.Once the model is validated using the two-dimensional experimental data, themodel will be used to simulate thin film formation and distributions in a threedimensionalnatural porous medium with hydraulically connected arbitrary poregeometries. Numerically simulated results on the geometry and extent of capillarycondensed zones will be compared to the microtomography data. The numerical modelwill then be used to map the spatial distribution of variables that cannot be measuredexperimentally such as fluid density, vapor pressure in thin films, interfacial width, andthree-dimensional curvatures, to subsequently calculate interfacial energies, surfacetension, chemical potentials, and disjoining pressures.Broader Impacts of the proposed research:We expect that the findings from the proposed research could have importantwider impacts in diverse fields where processes relevant to the low saturation regime areof significance, including arid zone irrigation and water management, fate and transportof contaminants and colloidal particles in the vadose zone, nuclear waste disposal in verydry climates, enhanced oil recovery, and in planetary sciences. In addition, the projectwill provide training for undergraduate and graduate students, as well as a post-doc.