• 대한토목학회논문집
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• 제13권1호
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• pp.97-103
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• 1993

두 개의 서로 다른 수문지질학적 성질을 갖는 다공성 매질이 대수층을 이룰 때, 수두분포를 적분방정식을 이용한 준해석적인 방법으로 구하는 방법을 연구하였다. 하단(下端)에서 지하수위(地下水位)의 위치가 알려져 있고, 하단(下端)에서의 경계조건이 일정수도 혹은 일정 유동량으로 주어질 때의 1차원 해석 알고리즘을 개발하고, 충적층(沖積層)(alluvium) 위에 석탄재(fly ash)를 매립하는 처분장의 경우에 적용하였다. 그 결과 얻어진 수두분포는 경계면 바로 윗부분에서 매우 큰 압력경사를 나타내었고, 이것이 수치해석을 어렵게 만드는 요인임을 발견하였다. 해석적으로 얻은 압력경사는 수치해석 수행시 격자(格子)의 배열을 어떻게 할 것인지에 대한 대안을 제시하였고, 그에 따른 수치해석 결과는 해석치와 근사함을 보였다.

• Geomechanics and Engineering
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• 제2권2호
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• pp.141-156
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• 2010

In the framework of meshfree methods, a new methodology is developed based on radial point interpolation method (RPIM). This methodology is applied to a one-dimensional contaminant transport modelling in the saturated porous media. The one-dimensional form of advection-dispersion equation involving reactive contaminant is considered in the analysis. The Galerkin weak form of the governing equation is formulated using 1D meshfree shape functions constructed using thin plate spline radial basis functions. MATLAB code is developed to obtain the numerical solution. Numerical examples representing various phenomena, which occur during migration of contaminants, are presented to illustrate the applicability of the proposed method and the results are compared with those obtained from the analytical and finite element solutions. The proposed RPIM has generated results with no oscillations and they are insensitive to Peclet constraints. In order to test the practical applicability and performance of the RPIM, three case studies of contaminant transport through the landfill liners are presented. A good agreement is obtained between the results of the RPIM and the field investigation data.

• 한국전산유체공학회지
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• 제12권1호
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• pp.22-27
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• 2007

Automobile underhood thermal and airflow simulation h α s been performed by using a commercial CFD program, FLUENT. To implement the radiation heat transfer effect to the underhood thermal and flow field, Discrete Ordinates Method(DOM) was used. The cooling fan was modeled by using the Multiple Reference Frame(MRF) technique. For the implementation of the heat exchangers, such as radiator and condenser, which are located in the front side of vehicle, the effectiveness-NTU model was used. The pressure drop throughout the heat exchangers was modeled as Porous media. For the validation of the current computational method, the coolant temperature at the inlet port of the radiator was compared with experimental data, and less than 3% error was observed. Finally, the composed model was used for the cooling fan spec determination process in the development of a new vehicle, and the results showed that the current CFD method could be successfully applied to the vehicle development process.

• 대한기계학회논문집B
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• 제25권4호
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• pp.572-582
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• 2001

A method of metal-hydride thermal conversion that is an alternative to the traditional method is proposed and investigated. The unit heat pump consists of reactors of two different metal-hydrides are distributed inside parallel channels filled with porous media. The channels are blown through with a heat-transfer agent. Thermal conversion develops as a set of successive heat waves. By a numerical-modeling method it is shown that the maximum thermal effect is attained in synchronous motion of the heat wave and the heat source (or sink) that accompanies the phase transition in the succession of unit metal-hydride pumps. The results are presented in a form convenient for prediction of the thermal and energy efficiency of the proposed thermal-conversion method in real devices.

• 상하수도학회지
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• 제10권3호
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• pp.64-72
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• 1996

The one of the most important factors we shoud consider in designing the processes using porous media such as activated carbon adsorber is the prediction of the breakthrough curve. In this study, the breakthrough curve of BAC process for the treatment of refractory pollutants was evaluated by simplified engineering analysis. Through the experiments, the slope of the breakthrough curve can be determined by retardation factor, R and apparent dispersion coefficient, $D_{app}$ which is determined by hydrodynamic dispersion, mass transfer effects and isotherm. Estimated concentration of effluent was agreed with the experimental values. Also, it is possible to use this method for predicting the breakthrough curve of the pollutants removal and tranport of pollutants in porous media.

• 설비공학논문집
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• 제5권4호
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• pp.243-248
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• 1993

In this research, unsteady groundwater flow in unconfined and homogeneous three layer aquifers is studied theoretically and experimentally. Numerical solutions are obtained by Runge Kutta and Runge Kutta Gill method after transforming the governing nonlinear partial differential equations to nonlinear ordinary differential equations. Experimental apparatus includes a test section filled with fine, medium and coarse sands. Experimental results are compared with the numerical solutions and both experimental and numerical results correspond well with each other. This numerical approach may be also applied to the cases which have more aquifers.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2010년도 정기 학술대회
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• pp.56-59
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• 2010

포화된 다공질 매체의 수치해석은 일반적으로 혼합유한요소방법(Mixed Finite Element Method)이 쓰인다. 이 혼합유한요소 방법은 고체변형과 유체의 이동을 동시에 고려하게 되는데 고체의 변형이 거의 없이 유체만 이동할 경우나 고체와 유체의 변형이 없이 간극수압만 존재할 경우에는 요소잠김현상(Element Locking)이 발생하여 혼합유한요소방법으로 해석하기에는 수치적으로 불안정해 진다. 본 논문에서는 이러한 수치적 불안정성을 해결한 스태거드 방법(Park and Tak 2010)을 소개하고 수치적 효율성을 위해 MPI(Message-Passing Interface) 라이브러리를 이용한 병렬해석 기법이 적용된다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1997년도 추계학술발표회논문집(1)
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• pp.451-456
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• 1997

Temperature distribution measurements in the mockup apparatus of reactor vessel were performed to determine the effective thermal conductivity of porous media with different geometry and to obtain the experimental data for the heat transfer processes by natural convection occurring in the air duct. The temperature distributions at four separated sections with different arrangements of porous media have different slopes according to the geometrical configuration. From the measured temperature distribution, effective thermal conductivity have been derived using the least square fitting method. The test at air duct was performed to the high heat removal at 3.4kW/$m^2$ by the natural convection from the outer wall to the air. And also the temperature distributions in the air duct agree well with the 1/7th power-law turbulent temperature distribution. The obtained heat transfer data have been compared with the Shin's and Sieger's correlations.

• 대한설비공학회지:설비저널
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• 제15권4호
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• pp.388-395
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• 1986

Numerical solutions of two-dimensional, steady, and natural are investigated in a confined rectangular cavity with porous media. The saturated fluid is bounded by two isothermal vertical walls at different temperatures and two adiabatic horizontal walls. Governing equations are numerically solved by finite difference method with the up wind scheme. Distributions of streamline and temperature we. predicted for aspect ratios ranging from 0.1 to 1.0, Rayleigh numbers 50 to $10^4$, and tilt angles $0^{\circ}\;to\;60^{\circ}$. Representative plots of temperature and velocity field according to tilt angle are presented. The effects of aspect ratio, Rayleigh number, and tilt angle on local and average Nusselt numbers are obtained. The optimum conditions for maximum Nusselt number are also presented with tilt angles.

• Advances in environmental research
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• 제3권1호
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• pp.45-69
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• 2014

The groundwater has been a major source of water supply throughout the ages. Around 50% of the rural as well as urban population in the developing countries like India depends on groundwater for drinking. The groundwater is also an important source in the agriculture and industrial sector. In many parts of the world, groundwater resources are under increasing threat from growing demands, wasteful use and contamination. A good planning and management practices are needed to face this challenge. A key to the management of groundwater is the ability to model the movement of fluids and contaminants in the subsurface environment. It is obvious that the contaminant source activities cannot be completely eliminated and perhaps our water bodies will continue to serve as receptors of vast quantities of waste. In such a scenario, the goal of water quality protection efforts must necessarily be the control and management of these sources to ensure that released pollutants will be sufficiently attenuated within the region of interest and the quality of water at points of withdrawal is not impaired. In order to understand the behaviour of contaminant transport through different types of media, several researchers are carrying out experimental investigations through laboratory and field studies. Many of them are working on the analytical and numerical studies to simulate the movement of contaminants in soil and groundwater of the contaminant transport. With the advent of high power computers especially, a numerical modelling has gained popularity and is indeed of particular relevance in this regard. This paper provides the state of the art of contaminant transport and reviews the allied research works carried out through experimental investigation or using the analytical solution and numerical method. The review involves the investigation in respect of both, saturated and unsaturated, porous media.