• Title/Summary/Keyword: Darcy′s law

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CFD Simulation Tool for Anode-Supported Flat-Tube Solid Oxide Fuel Cell

  • Youssef M. Elsayed.;Lim, Tak-Hyoung;Song, Rak-Hyun;Lee, Seung-Bok;Shin, Dong-Ryul
    • Journal of the Korean Electrochemical Society
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    • v.9 no.4
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    • pp.151-157
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    • 2006
  • A two-dimensional numerical model to study the performance of anode-supported flat-tube solid oxide fuel cell (SOFC) far the cross section of the cell in the flow direction of the fuel and air flows is developed. In this model a mass and charge balance, Maxwell-Stefan equation as well as the momentum equation by using, Darcy's law are applied in differential form. The finite element method using FEMLAB commercial software is used for meshing, discritization and solving the system of coupled differential equations. The current density distribution and fuel consumption as well as water production are analyzed. Experimental data is used to verify a predicted voltage-current density and power density versus current density to judge on the model accuracy.

Transverse permeability measurement of a circular braided preform in liquid composite molding

  • Chae, Hee-Sook;Song, Young-Seok;Youn, Jae-Ryoun
    • Korea-Australia Rheology Journal
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    • v.19 no.1
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    • pp.17-25
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    • 2007
  • In liquid composite molding (LCM), composites are produced by impregnation of a dry preform with liquid resin. The resin flow through the preform is usually described by Darcy's law and the permeability tensor must be obtained for filling analysis. While the resin flow in the thickness direction can be neglected for thin parts, the resin flow in the transverse direction is important for thicker parts. However, the transverse permeability of the preform has not been investigated frequently. In this study, the transverse permeability was measured experimentally for five different fiber preforms. In order to verify the experimental results, the measured transverse permeability was compared with numerical results. Five different fiber mats were used in this study: glass fiber woven fabric, aramid fiber woven fabric, glass fiber random mat, glass fiber braided preform, and glass/aramid hybrid braided preform. The anisotropic braided preforms were manufactured by using a three dimensional braiding machine. The pressure was measured at the inlet and outlet positions with pressure transducers.

Development of Wharf in Fishing Port with Tranquility Using the Arrays of Upright Perforated Plates ( 1 ) (직립 소파판을 이용한 어항 정온화 접안시설 개발 ( 1 ))

  • Kim, Hyeon-Ju;Cho, Il-Hyeong;Choi, Hak-Sun
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.32 no.3
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    • pp.286-293
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    • 1996
  • This paper established the analytical model of sea surface oscilation of simple type fishing port with vertical wave absorbor. This model is composed by MAEM(Matched Asymptotic Expansion Method) for wave amplification in fishing port and EEM(Eigen - function Expansion Method) for wave absorbing characteristics against vertical perforated plates. Dimensionless porosity by adopting Darcy's law was introduced to evaluate wave absorbing characteristics of the perforated structure. Using the model, the efficiency of the vertical perforated plates was studied for fishing port tranqulity with number of plates, array method and plate intervals. Optimal design and arrangement of perforated plates can be applied to develop multipurpose fishing ports and villages.

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Dynamic Characteristics Analysis of the Carriage Structure Supported by Air Bearing (에어베어링으로 지지된 캐리지 구조물의 동특성 해석)

  • 정순철;김덕수;유충준;장승환;이재응
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.05a
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    • pp.1107-1114
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    • 2003
  • In this thesis, the dynamic characteristic analysis of carriage structure supported by air bearings were peformed. Toward this end, the characteristics of air bearing were numerically analyzed to estimate the stiffness of the air bearing and the clearance between air bearing and guide surface. The modal analysis of the carriage structure was peformed by using finite element method, and the experimental modal analysis was also performed to validate the finite element model, where rigid body modes were compared to validate the stiffness of the air bearings. From the results, the air spring stiffness can be estimated within the range of acceptable accuracy under any pressure and clearance condition.

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Study on relations between porosity and damage in fractured rock mass

  • Xue, Xinhua
    • Geomechanics and Engineering
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    • v.9 no.1
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    • pp.15-24
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    • 2015
  • The porosity is often regarded as a linear function of fluid pressure in porous media and permeability is approximately looked as constants. However, for some scenarios such as unconsolidated sand beds, abnormal high pressured oil formation or large deformation of porous media for pore pressure dropped greatly, the change in porosity is not a linear function of fluid pressure in porous media, and permeability can't keep a constant yet. This paper mainly deals with the relationship between the damage variable and permeability properties of a deforming media, which can be considered as an exploratory attempt in this field.

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
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    • 1999.05a
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    • pp.207-212
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    • 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.

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Numerical modelling of Fault Reactivation Experiment at Mont Terri Underground Research Laboratory in Switzerland: DECOVALEX-2019 TASK B (Step 2) (스위스 Mont Terri 지하연구시설 단층 내 유체 주입시험 모델링: 국제공동연구 DECOVALEX-2019 Task B(Step 2))

  • Park, Jung-Wook;Guglielmi, Yves;Graupner, Bastian;Rutqvist, Jonny;Park, Eui-Seob
    • Tunnel and Underground Space
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    • v.29 no.3
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    • pp.197-213
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    • 2019
  • We simulated the fault reactivation experiment conducted at 'Main Fault' intersecting the low permeability clay formations of Mont Terri Underground Research Laboratory in Switzerland using TOUGH-FLAC simulator. The fluid flow along a fault was modelled with solid elements and governed by Darcy's law with the cubic law in TOUGH2, whereas the mechanical behavior of a single fault was represented by creating interface elements between two separating rock blocks in FLAC3D. We formulate the hydro-mechanical coupling relation of hydraulic aperture to consider the elastic fracture opening and failure-induced dilation for reproducing the abrupt changes in injection flow rate and monitoring pressure at fracture opening pressure. A parametric study was conducted to examine the effects of in-situ stress condition and fault deformation and strength parameters and to find the optimal parameter set to reproduce the field observations. In the best matching simulation, the fracture opening pressure and variations of injection flow rate and monitoring pressure showed good agreement with field experiment results, which suggests the capability of the numerical model to reasonably capture the fracture opening and propagation process. The model overestimated the fault displacement in shear direction and the range of reactivated zone, which was attributed to the progressive shear failures along the fault at high injection pressure. In the field experiment results, however, fracture tensile opening seems the dominant mechanism affecting the hydraulic aperture increase.

Wave Absorbing Characteristics of a Horizontal Submerged Punching Plate (수평형 타공판의 소파특성)

  • 조일형
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.14 no.4
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    • pp.265-273
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    • 2002
  • In this paper, wave absorbing characteristics of a horizontal submerged punching plate are investigated throughout the calculation and the experiment. The punching plate with the array of circular holes can force the flow to separate and to form eddies of high vorticity and cause significant energy loss. As an analytic tool, the linear water wave theory and the eigenfunction expansion method is applied. Darcy's law that the normal velocity of the fluid passing through the punching plate is linearly proportional to the pressure difference between two sides of the punching plate is assumed. The proportional constant called the porous coefficient is deeply dependent to the porosity. To obtain the relationship between the porosity and the porous coefficient the systematic model test for the punching plates with 6 different porosities is conducted at 2-dimensional wave tank. It is found that the porous coefficient is linearly proportional to the porosity(b=57.63P-0.9717). It is also noted that the optimal porosity value is near P=0.1 and the optimal range of submergence depth is $d/h\\leq0.2$ within entire frequency range.

Measurement and Numerical Model on Wave Interaction with Coastal Structure (해안구조물과 파랑상호작용에 관한 수치모델 및 실험)

  • Kim, In-Chul
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.21 no.1
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    • pp.30-38
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    • 2009
  • In recent years, there's been strong demand for coastal structures that have a permeability that serves water affinity and disaster prevention from wave attack. The aim of this study is to examine the wave transformation, including wave run-up that propagates over the coastal structures with a steep slope. A numerical model based on the nonlinear shallow water equation, together with the unsteady nonlinear Darcy law for fluid motion in permeable underlayer and laboratory measurements was carried out in terms of the free surface elevations and fluid particle velocities for the cases of regular and irregular waves over 1:5 impermeable and permeable slopes. The numerical results were used to evaluate the application and limitations of the PBREAK numerical model. The numerical model could predict the cross-shore variation of the wave profile reasonably, but showed less accurate results in the breaking zone that the mass and momentum influx is exchanged the most. Except near the wave crest, the computed depth averaged velocities could represent the measured profile below the trough level fairly well.

Wave Forces Acting on a Cylindrical Aquaculture Fish Cage (원통형 양식시설물에 작용하는 파랑하중)

  • Cho, Il-Hyoung
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.23 no.1
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    • pp.63-69
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    • 2011
  • In this paper, the wave forces on a cylindrical aquaculture fish cage, which consists of the porous mesh with the uniform porosity, are analyzed using matched eigenfunction expansion method. The boundary condition on the porous net is derived based on the Darcy's law, which implies that the velocity of the fluid passing through the net is linearly proportional to the pressure difference between two sides of the net. The wave forces and wave responses are investigated by changing the porous parameter of porous net as well as the submerged position (floating type, bottom-mounted type) of an aquaculture fish cage. It is found that the wave forces on a bottom-mounted type are largely decreased compared with that on a floating type. Also, the porosity of the netting structure plays an important role in reducing the wave forces and the wave elevation in the vicinity of an aquaculture fish cage.