부산대학교 도서관

In the past several decades there have been considerable advances in numerical simulations, and these have been widely applied in many fields. The finite element method is a powerful numerical scheme, due to its flexibility with regard to many complex, practical applications. However, initiating a full set of the scheme involves many routinely tedious data operations with regard to each element, and this can be an error-prone process. To overcome this difficulty, FreeFEM++ (Free Finite Element ++), a high level computational language for partial differential equations, was developed to customize these basic elementwise operations, allowing users to focus on the variational form of the physical governing equation, and thus enabling researchers or engineers to design specific numerical schemes. The additional benefits include the fact that FreeFEM++ is a public domain framework, and the number of users has been increasing in recent years. In the present study we applied FreeFEM++ to a contaminant transport problem. Contamination of groundwater due to heavy metals and organic compounds is one important environmental protection issue that has received considerable attention in recent years. It is important to choose an appropriate remediation method to achieve the most effective results at the lowest possible cost. For this reasons it is important to correctly estimate the physics of contamination transport in the underground environment, and simulations can be performed to better understand the groundwater and contamination hydrology and make predictions with regard to remediating treatments of the contaminated sites. The contaminated site in the present study is in Kaohsiung City, and is about 2,300 m^2 in size and was identified to be polluted with trichloroethylene (TCE) in 2001. The model of contaminant transport included two main parts: the Darcy’s groundwater flow and the advection-dispersion model. The effects of contaminant adsorption-desorption and natural attenuation were included. The remediation efforts at the contamination site began in 2001, in an attempt to confine the concentration of TCE and other contaminants at a controlled level. Therefore, a large set of observations and remediation data have been gathered, and we developed the present model based on the available data. The in-situ data were incorporated into the model by using kriging methods. The in-situ geo-statistical data included the initial concentration distribution of TCE, hydraulic conductivity and partition coefficients (Kd). For parameters that were not measured in the field, this study used the values obtained from laboratory experiments or from the literature. The simulation results show that the groundwater mainly flowed from west to east. The concentration of the contaminated plume between 2009 and 2010 was simulated, and the results agreed with the field observations. Seasonal variations of the contaminant concentration were observed. The effects of pollutant pumping will be simulated in future works, and its effectiveness with regard to remediation will also be investigated.