• Title/Summary/Keyword: Flow computation

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Analyses of Computation Time on Snakes and Gradient Vector Flow

  • Kwak, Young-Tae
    • Journal of the Korean Data and Information Science Society
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    • v.18 no.2
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    • pp.439-445
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    • 2007
  • GVF can solve two difficulties with Snakes that are on setting initial contour and have a hard time processing into boundary concavities. But GVF takes much longer computation time than the existing Snakes because of their edge map and partial derivatives. Therefore this paper analyzed the computation time between GVF and Snakes. As a simulation result, both algorithms took almost similar computation time in simple image. In real images, GVF took about two times computation than Snakes.

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Efficient Computation of Two-Phase Flow by Eulerian-Lagrangian Method Using Separate grids for the Particles and Flow Field (Eulerian-Lagrangian 방법에서 입자 및 유동 격자계 분리를 통한 2상 유동의 효율적 계산)

  • Pak S. I.;Lee J K.;Chang K. S.
    • 한국전산유체공학회:학술대회논문집
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    • 2003.08a
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    • pp.43-48
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    • 2003
  • When the Eulerian-Lagrangian method is used to analyze the particle laden two-phase flow, a large number of particles should be used to obtain statistically meaningful solutions. Then it takes too much time to track the particles and to average the particle properties in the numerical analysis of two-phase flow. The purpose of this paper is to reduce the computation time by means of a set of particle gird separate to the flow grid. Particle motion equation here is the simplified B-B-O equation, which is integrated to get the particle trajectories. Particle turbulent dispersion, wall collision, and wall roughness effects are considered but the two-way coupling effects between gas and particles are neglected. Particle laden 2-D channel flow is solved and it is shown that the computational efficiency is indeed improved by using the current method

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The comparison between Numerical Computation and Experiment on Fluid Elow in Rectangular Duct (사각덕트내의 유체유동에 관한 수치계산과 실험의 비교)

  • Yoon Young-Hwan;Bae Taeg-Hee;Park Won-Gu
    • Proceedings of the KSME Conference
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    • 2002.08a
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    • pp.71-74
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    • 2002
  • Fluid flow in a rectangular duct system are measured by W laser doppler velocity meter, and also computed by commercial software of STAR-CD for comparison between then First, for a rectangular duct with 90 degree metered elbow, the fluid flow with Reynolds numbs's of 1,508 is predicted by assumption of both laminar and turbulent models. But, even though the Reynolds number is less than 2,300-3,000, the computation by turbulent model is close to the experimental data. Moeover, the computation by turbulent model for Reynolds number of 11,751 also predicts the experimental data satisfactorily. Second, for a rectangular duct with two branch ducts, the ratios between flow rates in the two branches are invariant to Reynolds number according to both of numerical and experimental results.

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Design of a Node Label Data Flow Machine based on Self-timed (Self-timed 기반의 Node Label Data Flow Machine 설계)

  • Kim, Hee-Sook;Jung, Sung-Tae;Park, Hee-Soon
    • Proceedings of the KIEE Conference
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    • 1998.11b
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    • pp.666-668
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    • 1998
  • In this paper we illustrate the design of a node label data flow machine based on self-timed paradigm. Data flow machines differ from most other parallel architectures, they are based on the concept of the data-driven computation model instead of the program store computation model. Since the data-driven computation model provides the excution of instructions asynchronously, it is natural to implement a data flow machine using self timed circuits.

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Study on Fluid Flow in Rectangular Duct past $90^{\circ}$ Mitered Elbow (사각덕트내 직각엘보우를 지난 유체유동에 관한 연구)

  • 윤영환;배택희;박원구
    • Journal of Advanced Marine Engineering and Technology
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    • v.26 no.6
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    • pp.670-678
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    • 2002
  • Fluid flow in a rectangular duct with $90^{\circ}$ mitered elbow is measured by 5W laser doppler velocity meter. The fluid flow is also computed by commercial software of STAR-CD for comparison between measured and computed velocity profiles in the duct. Reynolds numbers for the comparison are 1,608 and 11,751 based on mean velocity and hydraulic diameter of the duct. First, the fluid flow of Reynolds number equal to 1,608 is predicted by assumptions of both laminar and turbulent models. But, even though the Reynolds number is less than 2,300~3,000, the computation by turbulent model is closed to the experimental data than that by laminar model. Second, the computation for Reynolds number of 11,751 by turbulent model also predicted the experimental data satisfactorily.

THE STUDY OF AERO-ACOUSTICS CHARACTERISTIC BY BOUNDARY CONDITIONS (경계조건에 따른 공력음향 특성에 관한 연구)

  • Lee, S.S.;Kim, J.S.
    • 한국전산유체공학회:학술대회논문집
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    • 2009.04a
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    • pp.75-80
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    • 2009
  • The present paper focuses on the analysis of aero-acoustics characteristic by several boundary conditions. In this simulation, a high-order and high-resolution numerical schemes are used for the accurate computation of compressible flow with several boundary conditions including characteristic boundary conditions as well as extrapolation and zonal characteristic boundary condition. These boundary conditions are applied to the computation of two dimensional circular cylinder flows with Mach number of 0.3 and Reynolds number of 400. The computation results are validated with measurement datum and other computation results for the Strouhal frequency of vortex shedding, the mean drag coefficient and root-mean-square lift for the unsteady periodic flow regime. Secondary frequency is predicted by three kinds of boundary conditions characteristic.

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SPARSE NULLSPACE COMPUTATION OF EQULILBRIUM MATRICES

  • Jang, Ho-Jong;Cha, Kyung-Joon
    • Communications of the Korean Mathematical Society
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    • v.11 no.4
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    • pp.1175-1185
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    • 1996
  • We study the computation of sparse null bases of equilibrium matrices in the context of structural optimization and incompressible fluid flow. In our approach we emphasize the parallel computatin and examine the applications. New block decomposition and node ordering schemes are suggested, and numerical examples are considered.

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A Parallel Emulation Scheme for Data-Flow Architecture on Loosely Coupled Multiprocessor Systems (이완 결합형 다중 프로세서 시스템을 사용한 데이터 플로우 컴퓨터 구조의 병렬 에뮬레이션에 관 한 연구)

  • 이용두;채수환
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.18 no.12
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    • pp.1902-1918
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    • 1993
  • Parallel architecture based on the von Neumann computation model has a limitation as a massively parallel architecture due to its inherent drawback of architectural features. The data-flow model of computation has a high programmability in software perspective and high scalability in hardware perspective. However, the practical programming and experimentaion of date-flow architectures are hardly available due to the absence of practical data-flow, we present a programming environment for performing the data-flow computation on conventional parallel machines in general, loosely compled multiprocessor system in particular. We build an emulator for tagged token data-flow architecture on the iPSC/2 hypercube, a loosely coupled multiprocessor system. The emulator is a shallow layer of software executing on an iPSC/2 system, and thus makes the iPSC/2 system work as a data-flow architecture from the programmer`s viewpoint. We implement various numerical and non-numerical algorithm in a data-flow assembler language, and then compare the performance of the program with those of the versions of conventional C language, Consequently, We verify the effectiveness of this programming environment based on the emulator in experimenting the data-flow computation on a conventional parallel machine.

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Numerical Computation of Unsteady Flow in a Cavity Induced by an Oscillatory External Flow (외부유동에 의한 캐버티 내의 비정상 유동에 대한 수치계산)

  • Yong kweon Suh;Park, Yoon-Hwan;Park, Jun-Gwan;Moon, Jong-Ghoon
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.9 no.4
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    • pp.194-200
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    • 1997
  • A two-dimensional shallow-water flow around a cavity driven by a sinusoidally oscillating external flow was studied numerically. A container model of "T" shape was constructed in the numerical computation for comparison with the experimental observation. The numerical computation shows that the aspect ratio of the cavity is not much affecting the overall flow pattern, and for the aspect ratio 2, the deep region of the cavity has a stagnant flow motion. At larger Reynolds number, the flow field is characterized by many small vortices which are not present in the flow visualization. The flow pattern in the external region is in good agreement with the experimentally recorded particle trajectories. It turns out that two large coherent vortices situated in the exterior region of the cavity are responsible for clockwise and counterclockwise drift motions, in large scale, of particles.particles.

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Analysis of Three-dimensional Nonaxisymmetric Spin-up by Using Parallel Computation (병렬계산에 의한 비축대칭 3차원 스핀업 유동해석)

  • Park, Jae-Hyoun;Choi, Yoon-Hwan;Suh, Yong-Kweon
    • Proceedings of the KSME Conference
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    • 2001.06e
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    • pp.512-517
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    • 2001
  • In this study, spin-up flows in a rectangular container are analysed by using three-dimensional computation. In the numerical computation, we use the parallel computer system of PC-cluster type. We compared our results with those obtained by two-dimensional computation. Effect of velocity and vorticity on the flow is studied. The result shows that two-dimensional solution is in good agreement with the 3-D result. Attention is given to the region where the 3-D flow is significant.

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