含有透镜体的二维多孔介质溶质运移实验与模拟研究

发布时间：2018-03-14 12:36

本文选题：溶质运移　切入点：示踪剂　出处：《合肥工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：多孔介质水流及溶质运移研究一直以来对地下工程及地下水污染防治具有重要指导意义,其中示踪剂实验是一种重要的研究方法,但目前研究溶质运移实验中示踪剂浓度检测大多采用取样法,为了避免取样法对溶质运移带来的影响,本文运用图像分析法检测示踪剂溶度。此外关于透镜体对多孔介质溶质运移的影响的研究较少,本文在总结前人研究的基础上,建立了模拟二维多孔介质运移的物理模型,在达西流条件下将惰性示踪剂亮蓝分别通入均匀和含有透镜体的多孔介质中,研究示踪剂在二维模型中的运移情况,运用解析解模型和IGW模型对溶质运移的时间浓度穿透曲线进行模拟,并对不同条件下的数值模拟结果进行了分析讨论,从而得出惰性溶质运移有关的规律和机理。总结本文研究方法和实验成果,得出如下结论:(1)利用图像法取代取样法测定溶质运移过程中浓度变化,快速准确的量化溶质溶度,为以后研究多孔介质溶质运移提供一种科学简单的检测方法。(2)多孔介质模型实验中虽然透镜体的大小和位置发生变化,但水力梯度和流速都呈线性关系,可以用传统达西定律进行拟合,且当水力梯度J相同时,随着透镜体大小H的增大渗透系数K变小。(3)在对溶质运移穿透曲线进行解析解和IGW拟合效果对比可发现:在均质多孔介质中,两者的拟合评价参数r2和RMSE相差不大,均可以很好的拟合溶质运移过程;而在含有透镜体的多孔介质中,随着透镜体的增大,解析解模型拟合参数r2值逐渐变小,RMSE值却逐渐增大,而IGW模型的r2值和RMSE值变化不大,且均比解析解的r2更接近1,RMSE值更加接近0,IGW模型具有更高的拟合精度。(4)通过比较不同条件下亮蓝浓度穿透曲线发现,随着透镜体和运移距离的增大,亮蓝浓度峰值到达的时间逐渐变长且峰值逐渐变小,模拟参数弥散系数D随之变大,出现非费克现象;当流速增大,亮蓝浓度到达峰值时间逐渐变短且峰值逐渐变大,弥散系数D随之变大,出现非费克现象。
[Abstract]:The study of water flow and solute transport in porous media has always been of great significance to underground engineering and groundwater pollution prevention and control, among which tracer experiment is an important research method. However, the concentration of tracer in solute transport experiments is mostly detected by sampling method, in order to avoid the influence of sampling method on solute transport. In this paper, the tracer solubility is detected by image analysis. In addition, there are few studies on the effects of lens on solute transport in porous media. Based on the previous studies, a physical model for simulating the migration of two-dimensional porous media is established in this paper. In the Darcy flow, the inert tracer bright blue was injected into a homogeneous porous medium containing a lens, respectively, and the migration of the tracer in a two-dimensional model was studied. The analytical solution model and IGW model are used to simulate the time concentration penetration curve of solute transport. The numerical simulation results under different conditions are analyzed and discussed. The research methods and experimental results in this paper are summarized, and the following conclusions are drawn: (1) using image method instead of sampling method to determine the concentration change in the process of solute transport, rapidly and accurately quantifying solute solute solubility. In the model experiment of porous media, although the size and position of the lens change, the hydraulic gradient and velocity are linearly related. It can be fitted with traditional Darcy's law, and when the hydraulic gradient J is the same, When the permeability coefficient K becomes smaller with the increase of lens size H) the analytical solution of solute migration penetration curve is compared with the IGW fitting results. It is found that in homogeneous porous media, the fitting evaluation parameters R2 and RMSE are not different from each other. In porous media containing lens, the fitting parameter R2 of analytical solution model becomes smaller and smaller, but the value of R2 and RMSE of IGW model change little with the increase of lens body, but the solute migration process can be fitted well in porous media with lens body, but the value of RMSE increases gradually with the increase of lens body, but the value of RMSE and RMSE of IGW model do not change much with the increase of lens body. Compared with the analytical solution, the RMSE value of R2 is closer to that of the model with a higher fitting accuracy. (4) by comparing the penetration curves of bright blue concentration under different conditions, it is found that with the increase of lens body and migration distance, The time to reach the peak value of bright blue becomes longer and the peak value becomes smaller, the dispersion coefficient D of the simulation parameter becomes larger, and the non-Fecker phenomenon occurs, and when the velocity of flow increases, the time to reach the peak value of bright blue concentration gradually becomes shorter and the peak value becomes larger. The dispersion coefficient D increases with it and the non-Fecker phenomenon appears.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X523;P641.2

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