• Title/Summary/Keyword: Sharp Interface

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Estimation of the Interface of Seawater Intrusion in a Coastal Aquifer System with SHARP Model (SHARP 모델을 이용한 해안 대수층의 해수침투 경계면 추정)

  • 심병완;정상용
    • Journal of Soil and Groundwater Environment
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    • v.8 no.1
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    • pp.68-74
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    • 2003
  • SHARP numerical model was used to estimate the interface, ranges and seasonal variations of seawater intrusion. The interface obtained from the SHARP model represented more sensitive to seasonal variations than that estimated from the monitoring wells. When TDS and groundwater velocity vector distributions generated by SUTRA simulations are compared to the interfaces obtained from SHARP simulation, the difference of the range on seawater intrusion is less than 50 m, and the range of seawater intrusion from seasonal variations has the difference of about 12 m. These differences are small for the numerical simulation of the coastal aquifer at regional scale. Therefore, the model with sharp interface is very useful to estimate the interface at this study site, where is regional aquifer system in the scale of seawater infusion. However the SHARP model have some limitations in simulating the range of seawater intrusion, when the hydrodynamic dispersion is significant for seawater intrusion at local aquifer system.

Applicability of a Sharp-Interface Model in Simulating Saltwater Contents of a Pumping Well in Coastal Areas (모래상자 수리모형실험을 통한 경계면 모델의 관정 염도 모의실험)

  • Shi, Lei;Cui, Lei;Lee, Chan-Jong;Hong, Sung-Hoon;Park, Nam-Sik
    • The Journal of Engineering Geology
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    • v.19 no.1
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    • pp.9-14
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    • 2009
  • In this work applicability of a sharp-interface model to well-scale problems is examined. In coastal areas one of the main concerns in groundwater development is saltwater intrusion. To determine the saltwater intrusion at a well one needs to evaluate the saltwater content from a pumping well. We conducted laboratory sand-tank experiments to determine if a sharp-interface model can simulate the saltwater content of a pumping well. Lateral saltwater intrusion experiments and freshwater lens experiments are conducted. A partially penetrating well and a fully penetrating well are used. Comparison between numerical results and observation results indicates that the sharp-interface model can determine saltwater contents reasonably well. We conclude that a sharp-interface model can be applied to well-scale groundwater flow problems in coastal areas.

Validation of Fresh-Saltwater Sharp-Interface Model Using Freshwater Lens Hydraulic Experiment (담수렌즈 수리모형을 이용한 담수-염수 경계면 수치모델의 검정)

  • Hong, Sung Hun;Park, Namsik
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.3B
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    • pp.263-269
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    • 2006
  • An optimization model was developed for groundwater development and management in coastal areas. The optimization model consists of coastal groundwater flow model and optimization techniques. The objective of this work is to validate sharp-interface model which is one of major components of the optimization model. A laboratory experimental model is built to simulate freshwater lens, i.e., layer of freshwater floating on top of saltwater, phenomena. Experimental results for the position of fresh-saltwater sharp-interface and the salinity in well are compared with numerical results. Average ratio of relative error is estimated approximately between 2.91% and 4.39%. And the numerical results are in good agreement with the laboratory results of water quality in well in addition to the position of sharp-interface. Accordingly the evaluation of coastal groundwater flow using sharp-interface model can produce reasonable results.

Experimental and Numerical Analyses of Unsteady Tunnel Flow in Subway Equiped with Platform Screen Door System (스크린도어가 설치된 지하철에서 열차운행에 의한 비정상유동의 실험 및 수치적 해석)

  • Kim Jung-Yup;Kim Kwang-Yong
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.18 no.2
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    • pp.103-111
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    • 2006
  • To optimize the ventilation and smoke control systems in subway equipped with platform screen door, the technology to analyze the unsteady tunnel flow caused by running of train should be developed. The development of model experiment and numerical analysis technique with relation to unsteady flow of subway were presented. The pressure and air velocity changes in 1/20-scaling experiment unit were measured and results were comparied to those of 3-D unsteady numerical analysis applied with sharp interface method. The experimental and numerical results were quantitatively similar and it would be reasonable to apply sharp interface method to analyze the unsteady flow in subway equipped with platform screen door.

PHASE FIELD MODELING OF CRYSTAL GROWTH

  • Sekerka, Robert F.
    • Proceedings of the Korea Association of Crystal Growth Conference
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    • 1996.06a
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    • pp.139-156
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    • 1996
  • The phase field model is becoming the model of choice for the theoretical study of the morphologies of crystals growth from the melt. This model provides an alternative approach to the solution of the classical (sharp interface) model of solidification by introducing a new variable, the phase field, Ø, to identify the phase. The variable Ø takes on constant values in the bulk phases and makes a continuous transition between these values over a thin transition layer that plays the role of the classically sharp interface. This results in Ø being governed by a new partial differential equation(in addition to the PDE's that govern the classical fields, such as temperature and composition) that guarantees (in the asymptotic limit of a suitably thin transition layer) that the appropriate boundary conditions at the crystal-melt interface are satisfied. Thus, one can proceed to solve coupled PDE's without the necessity of explicitly tracking the interface (free boundary) that would be necessary to solve the classical (sharp interface) model. Recent advances in supercomputing and algorithms now enable generation of interesting and valuable results that display most of the fundamental solidification phenomena and processes that are observed experimentally. These include morphological instability, solute trapping, cellular growth, dendritic growth (with anisotropic sidebranching, tip splitting, and coupling to periodic forcing), coarsening, recalescence, eutectic growth, faceting, and texture development. This talk will focus on the fundamental basis of the phase field model in terms of irreversible thermodynamics as well as it computational limitations and prognosis for future improvement. This work is supported by the National Science Foundation under grant DMR 9211276

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NUMERICAL SIMULATION OF THREE-DIMENSIONAL DENDRITIC GROWTH WITH FLUID CONVECTION (유체 유동을 동반한 수치상결정 미세구조의 3차원 성장에 대한 수치해석적 연구)

  • Yoon, Ik-Roh;Shin, Seung-Won
    • 한국전산유체공학회:학술대회논문집
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    • 2009.04a
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    • pp.355-362
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    • 2009
  • Most material of engineering interest undergoes solidification process from liquid to solid state. Identifying the underlying mechanism during solidification process is essential to determine the microstructure of material which governs the physical properties of final product. In this paper, we expand our previous two-dimensional numerical technique to three-dimensional simulation for computing dendritic solidification process with fluid convection. We used Level Contour Reconstruction Method to track the moving liquid-solid interface and Sharp Interface Technique to correctly implement phase changing boundary condition. Three-dimensional results showed clear difference compared to two-dimensional simulation on tip growth rate and velocity.

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Numerical Simulation of Dendritic Growth of the Multiple Seeds with Fluid Flow (유체 유동을 동반한 다핵 수치상결정의 미세구조성장에 대한 수치해석적 연구)

  • Yoon, Ik-Roh;Shin, Seung-Won
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.33 no.7
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    • pp.469-476
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    • 2009
  • Most material of engineering interest undergoes solidification process from liquid state. Identifying the underlying mechanism during solidification process is essential to determine the microstructure of material thus the physical properties of final product. In this paper, effect of fluid convection on the dendrite solidification morphology is studied using Level Contour Reconstruction Method. Sharp interface technique is used to implement correct boundary condition for moving solid interface. The results showed good agreement with exact boundary integral solution and compared well with other numerical techniques. Effects of Peclet number and undercooling on growth of dendrite tip of both single and multiple seeds have been also investigated.

Design of the Electric Stimulus Tactile Apparatus Loaded on the Haptic Interface Using Ultrasonic Motors (초음파 모터 구동 역감 장치에 부착한 전기자극 촉감 장치의 설계)

  • Kim Dong-Ok;Kang Won-Chan;Kim Sung-Cheol;Oh Geum-Kon;Kim Young-Dong
    • Proceedings of the KIPE Conference
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    • 2001.07a
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    • pp.9-13
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    • 2001
  • This paper proposes the electric stimulus tactile apparatus system(TESTAS) loaded on the hap-tic interface using ultrasonic motors(USMs). To touch the virtual object like wall in graphic, the 6 DOF haptic interface provides force feedback to users as if it is real. But the case of sharp virtual object like a puncture, it could not provided the sense of pain, but only the reaction-force. After the TESTAS had been loaded on this haptic interface. it could Provide not only the force but also the pain to users. To estimate the capability of TESTAS, we did experiments of three cases, one was very sharp, another was dull, the other is continuative contact.

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Fabrication of ultra-sharp tungsten tip using electro-chemical etching system (전기화학적 에칭방법을 이용한 초미세 바늘 전극 제작)

  • 오현주;장동영;강승언
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2004.04a
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    • pp.449-452
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    • 2004
  • To obtain the ultra-sharp tungsten tip, an analog to digital converter circuit aided by a personal computer has been setup. At the moment the lower part of the needle drops off during the etching process, a maximum current change across the reference resistor is detected by the PC interface card and the applied voltage is then cut off within a few milliseconds. Out experiment has been able to fabricate an ultra-sharp tungsten tip ~200 $\AA$ radius with a higher reproduction rate and reliability than the conventional method.

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Development of a Interface Structure of Bogie and Carbody in Mountain Tram running on sharp Curves (급곡선 급경사 운행 산악트램의 대차 및 차체 연결 구조 개발)

  • Seo, Sung-il;Mun, Hyung-Suk
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.7
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    • pp.275-282
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    • 2018
  • Mountain trams are an environmental-friendly transportation system that run wirelessly on an embedded track constructed on previous mountain roads, and can run despite the frozen road. On the other hand, there is some difficulty on sharp and steep tracks. In this study, after possible technical problems were defined in mountain trams running on a sharp and steep track, the design solutions for the interface structure of bogie and carbody were proposed. In addition, a prototype was made and its performance was tested to verify the solutions. Because the difference in the distance of the inner and outer rails on a sharp curve is severe enough to interrupt running, independent rotating wheels with different angular speeds were developed and applied. To prevent derailment due to the large attack angle and lateral force caused by the previous vehicle of 2bogie-and-1carbody on the sharp curve, a vehicle with 1bogie-and-1carbody was designed and applied. A prototype vehicle of 1bogie-and-1carbody with independent rotating wheels was made to improve the performance during the test running on a small track. A coupler was designed to absorb the large rotations of 3 degrees-of-freedom between the carbodies of a mountain tram running on the steep curved track. After a small scale prototype was made, the performance was verified by a function test.