• Title/Summary/Keyword: 유체확산

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NUMERICAL DIFFUSION DECREASE OF FREE-SURFACE FLOW ANALYSIS USING SOURCE TERM IN VOLUME FRACTION TRANSPORT EQUATION (볼륨비 이송방정식의 소스항을 이용한 자유수면 유동 해석의 해 확산 감소)

  • Park, Sunho;Rhee, Shin Hyung
    • Journal of computational fluids engineering
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    • v.19 no.1
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    • pp.15-20
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    • 2014
  • Accurate simulation of free-surface wave flows around a ship is very important for better hull-form design. In this paper, a computational fluid dynamics (CFD) code, termed SNUFOAM, which is based on the open source libraries, OpenFOAM, was developed to predict the wave patterns around a ship. Additional anti-diffusion source term for minimizing a numerical diffusion, which was caused by convection differencing scheme, was considered in the volume-fraction transport equation. The influence of the anti-diffusion source term was tested by applying it to free-surface wave flow around the Wigley model ship. In results, the band width of the volume fraction contours between 0.1 to 0.9 at the hull surface was narrowed by considering the anti-diffusion term.

Physics-Based Cloth and Liquid Interaction using GPU Optimization (GPU 최적화를 이용한 물리 기반 옷감과 액체의 상호작용)

  • Seong-Hyeok Moon;Jong-Hyun Kim
    • Proceedings of the Korean Society of Computer Information Conference
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    • 2023.01a
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    • pp.395-398
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    • 2023
  • 본 논문에서는 물리 기반 옷감 시뮬레이션과 SPH(Smoothed particle hydrodynamics) 기반의 유체 시뮬레이션 간의 상호작용에서 표현되는 다양한 물리적 효과를 GPU 기반으로 빠르게 표현할 수 있는 프레임워크를 제안한다. 기존 기법과는 다르게 수치적 안정성을 개선하기 위해 CCD(Continuous collision detection)를 활용하였으며, 모든 연산이 GPU에서 동작하기 때문에 매우 빠르게 옷감과 유체의 상호작용 장면인 다공성 재질, 기공 흐름, 흡수, 방사, 확산을 모델링할 수 있다.

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Simulations of Pollutant Dispersion over Rectangular Building (사각 건물 주위의 오염물 확산에 대한 수치해석적 연구)

  • Hong B. Y.;Park C. G.
    • Journal of computational fluids engineering
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    • v.6 no.4
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    • pp.1-7
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    • 2001
  • Wind flow perturbations, recirculations and turbulence generated by buildings often dominate air pollutant distributions around buildings. This paper describes dispersion of contaminants in the vicinity of a building by solving the concentration equation based on previously simulated wind flow field. Turbulence closure is achieved by using the standard k-ε two-equation model. The paper shows application of the CIP method for solving a species concentration equation of contaminant gas around a rectangular building for two different sources under conditions of neutral atmospheric stratification. Results have been compared to the experimental data and the previous numerical results by hybrid scheme. The computational results of concentration profiles by the CIP method agree well with experimental data.

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Numerical Simulations of the Flowfield and Pollutant Dispersion over 2-D Bell-Shaped Hills (2차원 종형 언덕 주위의 유동 및 확산현상에 관한 수치해석 연구)

  • Park K.;Park W. G.
    • Journal of computational fluids engineering
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    • v.3 no.1
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    • pp.63-72
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    • 1998
  • The numerical simulations of flowfield and pollutant dispersion over two-dimensional hills of various shapes are described. The Reynolds-averaged Wavier-Stokes equations and concentration diffusion equation based on the gradient diffusion theory have been applied to the atmospheric shear flow over the bell-shaped hills which are basic components of the complex terrain. The flow characteristics such as velocity profiles of the geophysical boundary layer, speed-up phenomena, mean pollutant concentration profiles are compared with experimental data to validate the present numerical procedure and it has been found that the present numerical results agree well with experiments and other numerical data. It has been also found that the distributions of ground level concentration are strongly influenced by the source location and height.

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Experiment of Characteristic Diffusion Time of Viscoelastic Fluid by Particle Image Velocimetry (PIV를 이용한 점탄성 유체의 특성 확산시간에 대한 측정)

  • 전찬열
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.3 no.4
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    • pp.251-256
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    • 2002
  • The average diffusion time of a polyacrylamide solution was determined by measuring the terminal velocities of the falling balls. The diffusion time increased as the polyacrylamide concentration increased. The PIV (Particle Image Velocimetry) system was employed to visualize the flow phenomena around balls. For a time interval of 30 seconds in the 2000 wppm, velocity vectors were larger than in case of 0 seconds, 40 seconds and 50 seconds in the falling ball. However, in the Newtonian fluid, flow vsualization around balls were performed at both upstream and downstream of the falling ball.

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Evaluation of Pressurized Water Diffusion in Water Treatment Process Using CFD (전산유체역학(CFD)를 활용한 정수공정에서 압력수 확산공정 진단)

  • Cho, Young-Man;Yoo, Soo-Jeon;Roh, Jae-Soon;Bin, Jae-Hoon;Choe, Kwang-Ju;Lee, Kwang-Ug;Lee, Gi-Bong;Lee, Jeong-Gyu
    • Journal of Korean Society of Environmental Engineers
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    • v.33 no.5
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    • pp.359-367
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    • 2011
  • The Process of Pressurized water diffusion is mixing process by pressurized water injection with coagulate and chlorine water in the water treatment system. The objectives of this research were to evaluate the mixing length and diameter of diffusion plate and distance from injection pipe for complete mixing by using computational fluid dynamics. From the results of CFD simulation, when diameter of injection pipe is 50 mm, 100 mm and injection pressure is $5kg/cm^2$ and the diameter of inlet pipe is 2,200 mm, the complete mixing length is 4D (D: Length as diameter of inlet pipe). When diameter of injection pipe is 50 mm, the diameter of the diffusion plate in o.1D and distance from injection pipe is 0.2D, the complete mixing length is 3D that is the most short mixing length. But when diameter of injection pipe is 100 mm and mutually related the diameter, distance of diffusion plate, the complete mixing length is 4D over. Therefore, as the diameter of inlet pipe is 2,200 mm, the injection pipe 50 mm is more efficient than 100 mm.

열 확산에 의한 미소입자의 부착현상에 관한 실험적 연구

  • 김상수;장혁상
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.9 no.3
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    • pp.379-386
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    • 1985
  • 본 연구에서는 부차적으로 이와 같은 광반사법의 유용성을 개발, 평가하고자 한다. 또 실험에서 벽면에 부착되는 입자는 기하학적 형상에 따라 입자주위의 유체 흐름에 지배적인 영향을 받게 되므로 실험을 통하여 입자의 기하학적 형상에 따라 변 화되는 열확산 효과의 상대적인 영향을 평가한다.

국지풍이 소규모만의 해수유동에 미치는 영향

  • 이충일;김동선;조규대
    • Proceedings of the Korean Society of Fisheries Technology Conference
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    • 2001.05a
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    • pp.244-245
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    • 2001
  • 육상 환경과 인접해 있는 연안해양환경은, 그 변화 특성이 매우 독특하며 복잡하게 나타난다. 해양환경 변화에 큰 영향을 미치는 것 중에는 해류와 조류 등과 같은 유체의 운동의 역할이 크다. 특히 바람과 같은 기상환경인자는 해표면의 유체의 운동에 큰 영향을 주게 되며, 이로 인하여 유체내의 입자물질(적조생물, 유류 등)의 집적 및 확산에 결정적인 영향을 끼치게 된다. 우리 나라는 계절풍이 뚜렷하게 나타나는 지역이지만, 지역에 따라서는 주변 지역과의 기압배치 및 지형적인 요인등에 의해서 그 특성이 충분히 변할 수 있다. 이러한 지역적인 국지풍은 만과 같은 소규모 지역에서 큰 영향을 끼칠 것으로 생각된다. (중략)

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Fiber-optic biosensor for the detection of organophosphorus compounds in a contaminated water (Part II : The signal analysis and simulation) (오염수 내의 유기인 화합물의 측정을 위한 광섬유 바이오센서 (제 2 부 : 신호분석 및 수치모사))

  • Choi, Jeong-Woo;Min, Jun-Hong;Lee, Won-Hong
    • Journal of Sensor Science and Technology
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    • v.3 no.2
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    • pp.16-23
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    • 1994
  • Developed fiber-optic biosensor for the detection of organophosphorus compounds in a contaminated water needs the analysis of an enzyme kinetics and the transport phenomena in the reaction part to analyze the sensor signal and to design the sensor. The enzyme inhibition kinetics was investigated and the reactor model was proposed to design the reaction part in the proposed sensor. Since the acetylcholinesterase was inhibited by the organophosphorus compounds, experiments for enzyme inhibition reaction were performed from 0 to 2 ppm to be detected by the developed sensor, and irreversible enzyme inhibition kinetics was proposed. The reactor parts were divided into the two phases, i.e. bulk phase and immobilized enzyme layer, to analyze the flow and diffusion. Sensor signal was able to be analyzed based on the total reactor model established by linking the enzyme reaction kinetics. Based on the proposed model, the effects of loading enzyme amount and enzyme layer thickness on the magnitude of readout signal were simulated.

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Efficient Representation of Pore Flow, Absorption, Emission and Diffusion using GPU-Accelerated Cloth-Liquid Interaction

  • Jong-Hyun Kim
    • Journal of the Korea Society of Computer and Information
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    • v.29 no.6
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    • pp.23-29
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    • 2024
  • In this paper, we propose a fast GPU-based method for representing pore flow, absorption, emission, and diffusion effects represented by cloth-liquid interactions using smoothed particle hydrodynamics (SPH), a particle-based fluid solver: 1) a unified framework for GPU-based representation of various physical effects represented by cloth-liquid interactions; 2) a method for efficiently calculating the saturation of a node based on SPH and transferring it to the surrounding porous particles; 3) a method for improving the stability based on Darcy's law to reliably calculate the direction of fluid absorption and release; 4) a method for controlling the amount of fluid absorbed by the porous particles according to the direction of flow; and finally, 5) a method for releasing the SPH particles without exceeding their maximum mass. The main advantage of the proposed method is that all computations are computed and run on the GPU, allowing us to quickly model porous materials, porous flows, absorption, reflection, diffusion, etc. represented by the interaction of cloth and fluid.