• Title, Summary, Keyword: 다공매체

Search Result 47, Processing Time 0.04 seconds

Study on the Hydraulic and Thermal Characteristics of Metallic Porous Medium (다공성 금속의 수력 및 열 교환 특성에 관한 연구)

  • Jin, M.H.;Kim, P.H.;Lee, Y.H.;Chung, H.S.;Jeong, H.M.
    • Journal of the Korea Society For Power System Engineering
    • /
    • v.12 no.5
    • /
    • pp.54-58
    • /
    • 2008
  • 최근 열교환기의 향상을 위해 발포다공성매체의 적용이 증가하고 있다. 열교환기의 적용에 있어서 발포다공성매체의 이점을 살펴보기 위해 본 연구에서는 2가지 실험을 수행하였다. 첫 번째는 수력의 관점에서 투과계수 및 내부계수를 결정하는 것이고, 두 번째는 열교환의 관점에서 다공성매체의 유효전도율을 측정하는 것이다. 본 실험에서는 기공도는 거의 같으나 기공의 크기가 각각 20 ppi와 40 ppi인 구리 다공성매체를 사용하였다. 실험의 결과는 40 ppi 크기의 다공성매체가 수력과 열교환, 두가지 관점 모두에서 보다 높은 저항 효율을 나타낸다는 것을 보여준다.

  • PDF

Incremental Excavation Analysis of Fluid-Saturated Ground (고체/유체 혼합체 이론모델에 의한 지반굴착해석)

  • 구정회;홍순조
    • Computational Structural Engineering
    • /
    • v.6 no.2
    • /
    • pp.17-22
    • /
    • 1993
  • 본 고에서는 다공매체에서 고체/유체의 상호작용을 조합해석할 수 있는 유한요소모델 개발현황을 살펴보고 이를 이용하여 다공매체의 단계적 굴착 시뮬레이션을 수행할 때 현재 널리 사용하고 있는 전응력해석에 의한 결과와의 차이점을 살펴보고자 한다.

  • PDF

Theoretical Formulation of Porous Medium Behavior Depending on Degree of Saturation (포화도에 따른 다공질 매체 거동의 이론적 정식화)

  • Park, Tae Hyo;Jung, So Chan;Kim, Won Cheul
    • Journal of the Korean Geoenvironmental Society
    • /
    • v.2 no.3
    • /
    • pp.81-88
    • /
    • 2001
  • The behavior of porous medium is modeled by linear thermoporoelastic behavior, linear poroviscoelastic behavior, poroplastic behavior, and poroviscoplastic behavior, etc. The behavior has, in general, a complicated aspect which makes a mechanical description of the problem with time. Constitutive modeling for deformation behavior of porous medium with coupling effects is needed since there is interaction between the constituents in pores with a relative velocity to each other. In this work, it is explained 3-dimensional behavior depending on degree of saturation for porous medium composed of homogeneous, isotropic materials. It is obtained the governing equations based on continuum porous mechanics. In addition, it is developed constitutive model which can be understood of behavior for porous medium which can be understood, analysed behavior of porous medium. It can be accomplished exact analysis and prediction of behavior in porous medium. The behavior for porous medium is analysed exactly, and the prediction of deformation behavior is accomplished. Consequently, it will be basis to analyze 3-dimensional behavior in municipal solid waste landfill, and the practical using of porous medium ground which are composed of nonhomogeneous, anisotropic materials can be done widely.

  • PDF

A Numerical Study on Flow in Porous Structure using Non-Hydrostatic Model (비정수압 수치모형을 이용한 다공성 구조물의 유동에 관한 수치적 연구)

  • Shin, Choong Hun;Yoon, Sung Bum
    • Journal of Korean Society of Coastal and Ocean Engineers
    • /
    • v.30 no.3
    • /
    • pp.114-122
    • /
    • 2018
  • This paper introduces a non-hydrostatic wave model SWASH for simulating wave interactions with porous structures. This model calculates the flow in porous media based on volume-averaged Reynolds-averaged Navier-Stokes equations (VARANS) in ${\sigma}$-coordinate. The empirical coefficients of resistance used to account for the flow in a porous media often need to be measured or calibrated. In this study, the empirical resistance coefficients used in the model are calibrated and validated using laboratory experiments, involving dam-break flow through porous media, and solitary wave interactions with a porous structure. It is shown that the agreement between experimental and numerical results is generally satisfactory. It is also confirmed that non-hydrodynamic model, SWASH, is computationally much more efficient than the three-dimensional porous flow models based on VOF approach.

Wave Propagation Characteristics in Saturated Porous Media I. Theoretical Solution (포화된 다공성매체에서 파동의 전파특성 I. 이론해의 유도)

  • Kim, Sun-Hoon;Kim, Kwang-Jin
    • Journal of the Computational Structural Engineering Institute of Korea
    • /
    • v.20 no.2
    • /
    • pp.95-103
    • /
    • 2007
  • An analytical closed-form solution for wave propagation velocity and damping in saturated porous media is presented in this paper The fully coupled field model with compressible solid Brains and pore water were used to derive this solution. An engineering approach for the analysis of fully saturated porous media was adopted and closed-form solutions for one dimensional wave propagation in a homogeneous domain were derived. The solution is highly versatile in that it considers compression of the solid grains, compression of the pore water, deformation of the porous skeleton, and spatial damping and can be used to compute wavespeeds of first and second kind and damping coefficients in various geologic materials. This solution provides a means of analyzing the influence of material property variations on wavespeed and attenuation. In Part 2 of this work the theoretical solution is incorporated into the numerical code and the code is used in a parametric study on wave propagation velocity and damping.

Finite Element Analysis and Local a Posteriori Error Estimates for Problems of Flow through Porous Media (다공매체를 통과하는 유동문제의 유한요소해석과 부분해석후 오차계산)

  • Lee, Choon-Yeol
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.21 no.5
    • /
    • pp.850-858
    • /
    • 1997
  • A new a posteriori error estimator is introduced and applied to variational inequalities occurring in problems of flow through porous media. In order to construct element-wise a posteriori error estimates the global error is localized by a special mixed formulation in which continuity conditions at interfaces are treated as constraints. This approach leads to error indicators which provide rigorous upper bounds of the element errors. A discussion of a compatibility condition for the well-posedness of the local error analysis problem is given. Two numerical examples are solved to check the compatibility of the local problems and convergence of the effectivity index both in a local and a global sense with respect to local refinements.

Estimation of Fluid Saturations Using Agarose Standard in NMR Imaging (자기 공명 영상법에서 Agarose 표준 물질을 사용한 유체 포화도의 계산)

  • Kim, Kyung-Hoe
    • Applied Chemistry for Engineering
    • /
    • v.10 no.1
    • /
    • pp.160-165
    • /
    • 1999
  • Agarose gels can be used as reference standards for the measurement of fluid properties in porous media because the relaxation properties of the gel reference standard and those of the fluid in porous media can be closely matched. The use of reference standard to determine porosity and saturation is discussed and the requirements for gel NMR properties given. The relaxtion times of agarose gels measured at 2.0 Tesla are illustrated as a function of agarose and paramagnetic impurity ($CuSO_4$) concentrations. This work shows an empirical result between agarose gel composition and gel relaxtion times. The average value for the porosity distribution is 17.7%, which compares well with the value calculated with the gravimetric analysis. Finally, two phase immiscible displacement using agarose gels as a reference standard was performed. The saturation profiles appear to be consistent with what one might calculate for a one-dimensional displacement in a uniform porous media.

  • PDF

Visualization and Quantification of Dissolution of Dense Nonaqueous Phase Liquid Entrapped in Porous Media (다공성 매체내 유기용매(DNAPL)의 용해현상 시각화 및 정량화 연구)

  • Ju, Byung-Kyu;Jeong, Seung-Woo
    • Journal of the Korea Organic Resources Recycling Association
    • /
    • v.16 no.1
    • /
    • pp.46-52
    • /
    • 2008
  • Oils and chlorinated solvents leaking to the subsurface are entrapped in the soil pore and these are called as nonaqueous phase liquids (NAPL). NAPL entrapped in porous media acts as a continuous source for surface and ground water contamination. This study visualized dissolution of trichloroethylene (TCE) entrapped in porous media and quantified the velocity of TCE dissolution using an image analysis technique. As the water velocity increased, the level of dissolution increased. The results imply that a TCE contaminated region having a high infiltration rate and groundwater velocity may result in severe groundwater contamination. Microscopic images of TCE entrapped in porous media showed that TCE present in the preferential flow paths was easily dissoluted into the water phase. However, TCE present in the stagnant flow region was visualized for long time. The results imply that TCE would be still present in the soil if TCE is detected in goundwater.

  • PDF

Finite Element Analysis for Incremental Excavation in Fluid-Saturated Porous Media (유체포화 다공매체의 단계적 굴착해석을 위한 유한요소해석방법)

  • Koo, Jeong Hoi;Hong, Soon Jo;Kim, Moon Kyum;Hwang, Hak Joo
    • Journal of The Korean Society of Civil Engineers
    • /
    • v.13 no.5
    • /
    • pp.109-122
    • /
    • 1993
  • ln this paper, a finite element analysis procedure is proposed for the incremental multi-step excavations in a fluid-saturated porous medium such as saturated soil ground. As the basis of derivation, Biot's equation was used. The proposed procedure was applied to some one- and two-dimensional problems under incremental excavations. Unsaturated cases as well as saturated cases were considered for comparison. Through numerical tests, the effects of permeability and excavation speed on the deformation history was investigated. Results showed that pore pressure built up during incremental excavation has a significant effect on the deformation and stresses of solid skeleton and validated the use of the present procedure for the analysis of multi-step excavations in fluid-saturated media such as in saturated shallow ground.

  • PDF

Transfer Characteristics of Porous Metallic Salt-Expanded Graphite Reactive Media (금속염-팽창흑연 다공성 반응매체의 전달특성)

  • 한종훈;김상욱;이건홍
    • Proceedings of the Korea Society for Energy Engineering kosee Conference
    • /
    • /
    • pp.207-212
    • /
    • 1999
  • 화학반응이 일어나는 고정층 반응기의 성능을 모사하고 해석하기 위해서는 반응베드의 열 및 물질전달 특성을 정확히 아는 것이 중요하다. 본 연구에서는 화학열펌프에 사용되는 금속염-팽창흑연 다공성 반응매체의 유효열전도도와 기체투과도를 측정하였다. 유효열전도도는 전이 일차원 열류기법을 이용하여 측정하였고, 기체투과도는 Darcy's law를 이용하여 측정하였다. 팽창흑연이 함유된 반응베드의 유효열전도도와 기체투과도는 흑연을 기준으로 한 겉보기밀도에 따라 각각 14.1-36.5 W/mK, 8.0x$10^{-15}$-$10^{-12}$ $m^2$의 범위에 있었다.

  • PDF