Mixing Rules at Pore and Fracture Junctions

9405837威尔逊我们建议使用数学模型和实验室实验来阐明孔隙体或裂缝连接尺度上的混合规律。传统的模型假定进入其中一个交界处的示踪剂或污染物要么混合良好，要么沿着流线穿过交界处。提出了一个元胞自动机数值模型和一个机械加工的Lucite实验微观模型来研究在这些极限之间存在一系列混合规则的假设。Peclet数将被用来定位在扩散控制和平流控制之间的流动位置，扩散控制导致良好混合规则，平流控制中污染物永远不会离开流线。孔洞或裂缝交界处的Peclet数定义为平均平流速度乘以孔洞/裂缝大小，除以扩散系数。在高速度和高Peclet数下，分流线上几乎没有混合，产生平流控制。当速度和Peclet数较小时，扩散占主导地位，导致完全混合。我们假设这些极限之间的转变大约跨越一个数量级的Peclet数，并且发生在Peclet数1附近。将使用格子气体自动机(LGA)和/或格子Boltzman方法同时对流动和输运进行数值模拟。这些方法适用于Peclet数接近1的情况，但已经开发了一种新的算法来有效地模拟非均匀流体的稀溶液，以便在保持雷诺数不变的情况下在大范围内经济地改变Peclet数。该实验方法采用了一个由四个相交通道组成的Lucite结的物理微观模型。为了适应预期的Peclet数范围、较低的雷诺数和合理的实验时间常数，通道和流量必须相当小。在低流速和低Peclet数下，实验对泄漏、温度波动和其他问题非常敏感。我们建立了一个初步的实验版本来阐明和解决这些问题。元胞自动机模拟和物理微观模型将被用来探索不同进入和退出流速的组合以及不同连接几何形状的混合。然后，我们将与其他研究人员合作，将这些规则应用于多孔系统和各种裂缝网络系统的渗流网络模型，以确定混合规则的空间分布，以及它们对力学和宏观弥散计算的影响。通过合作，我们将模拟网络中的混相驱替实验，包括混合、不混合和自适应混合规则，以进一步考察混合条件的范围。

9405837 Wilson We propose to use a mathematical model and laboratory experiments to elucidate the mixing rule at the pore body or fracture junction scale. Traditional models have assumed that tracers or contaminants entering one of these junctions are either well mixed, or follow flowlines through the junction. A cellular automata numerical model and a machined Lucite experimental micromodel are proposed to investigate the hypothesis that there is a range of mixing rules between these limits. The Peclet number would be used to position in flow between diffusion control leading to the well mixed rule, and advection control, with contaminants never leaving a flowline. A pore or fracture junction Peclet Number is defined as the mean advective velocity times pore/fracture size, divided by the diffusion coefficient. At high velocities and high Peclet Numbers there is little mixing across the dividing stream line, yielding advective control. At small velocities and Peclet numbers diffusion dominates, resulting in complete mixing. We hypothesize that the transition between these limits spans about an order of magnitude of Peclet numbers, and occurs near a Peclet number of 1. Lattice gas automata (LGA) and /or lattice Boltzman methods will be used to numerically simulate flow and transport simultaneously. These methods work well for Peclet numbers near one, but a new algorithm has been developed to efficiently model dilute solutions of non-homogeneous fluids in order to economically vary Peclet number over a large range, while holding Reynolds number constant. The experimental approach employs a Lucite physical micromodels of a junctions, consisting of four intersecting channels. In order to accommodate the expected range of Peclet numbers the low Reynolds number, and reasonable experimental time constants, the channels and flow rates must be quite small. At low flow rates and Peclet numbers the experiment is very sensitive to leaks, temperature fluctua tions, and other problems. We built a preliminary version of the experiment to elucidate and solve each of these problems. The cellular automata simulations and the physical micromodel will be used to explore mixing with different combinations of entering and exiting flow rates, and with different junction geometries. We will then work with other investigators to apply the rules to percolation network models of porous systems, and various fracture network systems, to determine the spatial distribution of mixing rules, and their effect on mechanical and macro-dispersion calculations. Through collaborations we will simulate miscible displacement experiments in the networks, with mixing, no-mixing and adaptive mixing rules, to further investigate the range of mixing conditions.