High Rayleigh Number Convection in Laboratory Porous Media

0309618 CooperObjectives：拟议研究的目的是确定地下多孔介质中不断发展的高瑞利数（Ra）热对流的长度和时间尺度。将被测试的具体假设是，流动模式有几个相互作用的运动尺度同时发生，相互影响。最小的尺度是从热边界层剥离的单个羽流，而最大的尺度是实验装置的大小。运动的长度和时间尺度以及时间热传递可以根据局部（边界层）和全局（系统）Rayleigh数、Nusselt数、Peclet数以及介质的不均匀性来理解。科学价值：热对流是一个重要的传输过程，可导致地壳区域的高热流率。虽然多孔介质中的很多焦点一直在封闭的对流细胞，导致在低瑞利数的受限介质，很少的研究，没有基本的实验，已经进行了参数空间中的细胞本身变得不稳定，过渡到湍流状态。方法：将在尺寸为1 m高x 1 m宽x 2 cm厚的填砂实验室试验室中进行一系列实验。垫层模式将使用不同大小的半透明硅砂（100？m至7 mm）。将在电池中心周围安装约75个热电偶阵列，以捕获cm级温度（因此流量）运动。 通过将热致变色液晶溶解在工作溶液（水）中，可以看到大规模的运动;这些晶体会随着温度的变化而改变颜色（红-绿-蓝）。更广泛的影响：这项研究将形成博士学位的论文部分。学生的课程在内华达州，里诺大学。这项研究是C.库珀开发的方法来理解地下流体力学作为地质剂的重要性。

0309618CooperObjectives: The objective of the proposed research is to determine the length and time scales of evolving high Rayleigh number (Ra) thermal convection in subsurface porous media. The specific hypothesis that will be tested is that flow patterns have several interacting scales of motion occurring simultaneously that influence each other. The smallest scales are individual plumes that peel away from a thermal boundary layer, while the largest scales are on the order of the size of the experimental apparatus. The length and time scales of motion, as well as temporal heat transfer can be understood in terms of the local (boundary layer) and global (system) Rayleigh numbers, the Nusselt number, the Peclet number, as well as the heterogeneity of the media. Scientific merit: Thermal convection is an important transport process that can result in high heat flow rates in regions of the Earth's crust. While much focus in porous media has been on the closed convection cells that result in confined media at low Rayleigh numbers, little research, and no fundamental experiments, have been conducted in parameter space where the cells themselves become unstable and transition to a turbulent regime. Methods: A series of experiments will be conducted in a sand-filled laboratory test cell with dimensions 1 m tall x 1 m wide x 2 cm thick. Bedding patterns will be constructed using translucent silica sands of varying sizes (100 ?m to 7 mm). An array of approximately 75 thermocouples will be installed around the center of the cell to capture cm-scale temperature (hence flow) motion. Large-scale motion will be visualized by dissolving thermochromic liquid crystals in the working solution (water); these crystals change color (red-green-blue) as a function of temperature. Broader impacts: This research will form the dissertation portion of a Ph.D. student's curricula at the University of Nevada, Reno. This research is part of a larger goal of C. Cooper to develop methods to understand the importance of subsurface fluid mechanics as a geologic agent.