COLABORATIVE RESEARCH: Closure of Thermodynamically Constrained Models for Multiphase Systems

[901660]米勒多孔介质中多相流的传统模型是基于经验主义和实验数据的相关性。在过去的二十年中，在建立基于守恒原理的多相流模型的理论基础方面付出了巨大的努力。这些方法都揭示了当前模型中隐含的假设，以及通往更严格、更健壮的模型的路径。热力学约束平均理论方法（TCATA）是最优雅和概念上令人满意的方法之一。最近与TCATA的合作已经形成了一套多孔介质中两相流的模型。然而，要充分发展TCATA，还需要采取额外的步骤。当前提案的目标是超越纯理论和理想化的多孔介质，以描述真实系统，以证明TCATA描述多孔介质中多相流物理的可行性、重要性和必要性。为了达到这个项目的目标，我们将结合理论、孔隙尺度形态和建模、连续尺度建模和实验室实验方法。这项工作将通过建立和继续北卡罗来纳大学的卡斯·t·米勒教授小组和圣母大学的威廉·g·格雷教授小组之间的现有合作来完成。该提案描述了两个小组的共同工作，每个机构直接向NSF提交完成其工作份额所需的资源。这项工作将有额外的适用性，任何阵列的多相多孔介质系统在自然和工程系统。我们期望从这项工作中取得几项重大成就：(1)建立一个包括膜流和分离压力的理论框架；(2)将毛细管压力表示为饱和度和界面面积的函数，从而减少或消除当毛细管压力仅表示为饱和度函数时发现的滞后；(3)发展了包含动态几何参数的本构关系，以表达相对渗透率的功能依赖性；(4)制定并实现求解模型方程扩展集的数值算法；(5)实验数据与模型结果的比较，揭示了我们的方法的优点和缺点，以及考虑多相流物理的方法进一步发展的需要。

9901660MillerTraditional models of multiphase flow in porous media are based in empiricism and correlation of experimental data. Over the past two decades significant effort has been expended in developing a theoretical basis for multiphase flow models grounded in conservation principles. These approaches both reveal assumptions implicit in the current models and paths to more rigorous and robust models. One of the most elegant and conceptually satisfying approaches is the thermodynamically constrained averaging theory approach (TCATA). Recent work with the TCATA has led to the formulation of a set of models for two-phase flow in porous media. Additional steps, however, are required to develop the TCATA fully. The goals of the current proposal are to move beyond pure theory and idealized porous media to the description of real systems to demonstrate the viability, importance, and necessity of the TCATA for describing the physics of multiphase flow in porous media.To meet the goals of this project, we will use a combination of theoretical, pore scale morphology and modeling, continuum scale modeling, and laboratory experimental approaches. This work will be accomplished by building upon and continuing an existing collaboration between Professor Cass T. Miller's group at the University of North Carolina and Professor William G. Gray's group at the University of Notre Dame. This proposal describes the joint work of both groups, with each institution submitting directly to NSF requesting the resources needed to accomplish their share of the work.This work will have additional applicability to any array of multiphase porous media systems in both natural and engineered systems. We expect several significant accomplishments from this work: (1) the development of a theoretical framework that includes film flow and disjoining pressures; (2) the formulation of capillary pressure as a function of both saturation and interfacial area, thereby reducing or eliminating the hysteresis found when capillary pressure is represented as a function of saturation only; (3) the development of constitutive relations that include dynamic geometric parameters in expressing the functional dependence of relative permeability; (4) formulation and implementation of a numerical algorithm to solve the extended set of model equations; and (5) comparison of experimental data with model results to reveal the strengths and weaknesses of our approaches and the needs for further advancement of methods that account for the physics of multiphase flow.