• Title/Summary/Keyword: Velocity Distribution

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ENTRAINMENT OF SEDIMENT PARTICLES FROM SCOUR HOLE BY TURBULENT VORTICES DOWNSTREAM OF HYDRAULIC STRUCTURE

  • Kim, Jin-Hong;Lee, Sam-Hee
    • Water Engineering Research
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    • v.2 no.4
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    • pp.261-268
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    • 2001
  • This study presents the estimation of the entrainment velocity of sediment particles from the scour hole. Sediment particles are entrained from the scour hole downstream of hydraulic structures by the turbulent vortices. Mathematical form of the entrainment velocity of sediment particles from the scour hole was obtained using the impulse-momentum equation with given value of the vertical component of turbulent velocity of the line vortex. Also, its probability density distribution was obtained with the results that the probability density distribution of the vertical turbulent velocity followed the normal distribution. Experimental results of the entrainment velocity of sediment particles showed relatively good agreements with theoretical ones.

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An Upper Bound Analysis of the Shapes of the Dead Metal Zone and the Curving Velocity Distribution in Eccentric Plane Dies Extrusion (평다이를 사용한 편심 압출가공에서의 비유동 영역의 형상과 굽힘 속도 분포에 관한 상계해석)

  • Kim, Jin-Hoon;Jin, In-Tai
    • Transactions of Materials Processing
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    • v.7 no.2
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    • pp.177-185
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    • 1998
  • The kinematically admissible veolcity field is developed for the shapes of dead metal zone and the curving velocity distribution in the eccentric plane dies extrusion. The shape of dead metal zone is defined as the boundary surface with the maximum friction constant between the deformable zone and the rigid zone. The curving phenomenon in the eccentric lane dies is caused by the eccentricity of plane dies. The axial velocity distribution in the plane dies is divided in to the uniform velocity and the deviated velocity. The deviated velocity is linearly changed with the distance from the center of cross-section of the workpiece. The results show that the curvature of products and the shapes of the dead metal one are determined by the minimization of the plastic work and that the curvature of the extruded products increase with the eccentricity.

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Effect of upflow liquid velocity on size and activity of granular sludge in Expended Granular Sludge Bed(EGSB) reactor (EGSB 반응조 운전시 상향유속이 입상슬러지의 크기 및 활성도에 미치는 영향)

  • 이헌모;정병곤
    • Journal of environmental and Sanitary engineering
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    • v.12 no.2
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    • pp.13-21
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    • 1997
  • The effect of upflow velocity on size distribution and activity of granular sludge was studied in laboratory-scale Expended Granular Sludge Bed(EGSB) reactor fed with non-fat dry milk and sucrose as sole carbon and energy source. High upflow velocity advanced size and activity of granular sludge by distribution and floatation of granular sludge. Therefore, the reactor operation of an apt upflow velocity was needed and an apt upflow velocity in this experimental was estimated to 1-10m/hr.

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Development of Longitudinal Dispersion Coefficient Based on Theoretical Equation for Transverse Distribution of Stream-Wise Velocity in Open Channel : Part II. Longitudinal Dispersion Coefficient (개수로에서 흐름방향 유속의 횡분포 이론식에 기반한 종분산계수 개발 : II. 종분산계수)

  • Baek, Kyong Oh
    • Journal of Korea Water Resources Association
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    • v.48 no.4
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    • pp.299-308
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    • 2015
  • The aim of this study is that a theoretical formula for estimating the one-dimensional longitudinal dispersion coefficient is derived based on a transverse distribution equation for the depth averaged stream-wise velocity in open channel. In "Part I. Theoretical equation for stream-wise velocity" which is the former volume of this article, the velocity distribution equation is derived analytically based on the Shiono-Knight Method (SKM). And then incorporating the velocity distribution equation into a triple integral formula which was proposed by Fischer (1968), the one-dimensional longitudinal dispersion coefficient can be derived theoretically in "Part II. Longitudinal dispersion coefficient" which is the latter volume of this article. The proposed equations for the velocity distribution and the longitudinal dispersion coefficient are verified by using observed data set. As a result, the non-dimensional longitudinal dispersion coefficient is inversely proportional to square of the Manning's roughness coefficient and the non-dimensional transverse dispersion coefficient, and is directly proportional to square of the aspect ratio (channel width to depth).

Calibration of Water Velocity Profile in Circular Water Channel Using Particle Image Velocimetry (PIV를 이용한 회류수조의 유속 분포 교정에 관한 연구)

  • Suh, Sung-Bu;Jung, Kwang-Hyo
    • Journal of Ocean Engineering and Technology
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    • v.25 no.4
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    • pp.23-27
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    • 2011
  • This experimental study was performed to find rpms of the impeller and the surface flow accelerator to make a uniform velocity vertical distribution in the circular water channel. PIV technique was employed to measure the water velocity profiles into the water depth from the free surface. The number of instantaneous velocity profiles was decomposed into mean and turbulence velocity components, and the distribution of velocity fluctuation and turbulence intensity were computed for each experimental condition. From these results, the velocity uniformity was quantitatively determined to present the flow quality in the measuring section of the circular water channel. It has been shown that the proper operation of the surface flow accelerator would make the uniform velocity profiles and reduce the velocity fluctuation near the free surface.

Upflow Velocity Effects on Behavior of Reaction Products in USAB Reactor (UASB 반응조에서 상향유속에 따른 높이별 반응생성물의 거동특성)

  • 이헌모;윤종호;정용현
    • Journal of environmental and Sanitary engineering
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    • v.13 no.2
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    • pp.14-25
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    • 1998
  • To investigate the behavior of reaction products with the reactor heights by the change of upflow velocity, a typical real height USAB reactor was built and experiment was conducted. The flow in the reactor by the upflow velocity was flug flow at low upflow velocity but the flow was completely mixed flow at high upflow velocity. Therefore, the concentration of pH, alkalinity and volatile acid was not so different with reactor heights at high upflow velocity. And comparing with low upflow velocity, the distribution of microorganisms with reactor heights did not show big different at high upflow velocity. The removal efficiency of organic compounds depended on the distribution of microorganisms and it was low at high upflow velocity. It is concluded that the operation of reactor with proper upflow velocity to improve contact with organic compounds and microorganisms is recommended.

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Comparison of the Vertical Velocity Distribution in the Natural Streamflow (자연하천의 연직방향 유속분포 비교(수공))

  • 박승기;김태철
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 2000.10a
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    • pp.346-351
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    • 2000
  • The study was carried out to investigate the characteristics of vertical velocity distribution measured by current meter at Kangkyung station in Keum river during the period of 1995 to 1997. It suggests the quadratic parabola equation to estimate the vertical velocity profile only from the measurement data of surface velocity. The equation was found to be statistically very stable and showed high significance to express the surface velocity and bottom velocity. The vertical velocity profile was determined by the relationships to the surface velocity, and a coefficient of the quadratic parabola equation. The vertical velocity profile can be applied to calculating the mean velocity and discharge, and to and to analyse the dispersion of pollutant materials in the streamflow.

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Nonequilibrium Molecular Dynamics Simulation Study of Kinetic Energy and Velocity Distribution Profiles of Argon Gases in Shock Waves (충격파 내에서 형성되는 아르곤 기체의 운동 에너지 분포와 속도 분포에 대한 비평형 분자동역학 모의실험 연구)

  • Hwang, Hyon-Seok;Lee, Ji-Hye;Kwon, Chan-Ho;Kim, Hong-Lae;Park, Min-Kyu;Kim, Seong-Shik
    • Journal of the Korea Institute of Military Science and Technology
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    • v.14 no.1
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    • pp.147-153
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    • 2011
  • A series of nonequilibrium molecular dynamics(NEMD) simulations are performed to investigate the kinetic energy and velocity distributions of molecules in shock waves. In the simulations, argon molecules are used as a medium gas through which shock waves are propagating. The kinetic energy distribution profiles reveals that as a strong shock wave whose Mach number is 27.1 is applied, 39.6% of argon molecules inside the shock wave have larger kinetic energy than molecular ionization energy. This indicates that an application of a strong shock wave to argon gas can give rise to an intense light. The velocity distribution profiles in z direction along which shock waves propagate clearly represent two Maxwell-Boltzmann distributions of molecular velocities in two equilibrium regions and one bimodal velocity distribution profile that is attributed to a nonequilibrium region. The peak appearing in the directional temperature in z direction is discussed on a basis of the bimodal velocity distribution in the nonequilibrium region.

Current Measurement and Velocity Spatial Distribution of Deep Ocean Engineering Basin

  • Jung, Sung-Jun;Jung, Jae-Sang;Lee, Yong-Guk;Park, Byeong-Won;Hwang, Sung-Chul;Park, In-Bo;Kim, Jin-Ha;Park, Il-Ryong
    • Journal of Ocean Engineering and Technology
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    • v.35 no.2
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    • pp.150-160
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    • 2021
  • To ensure the international competitiveness of the domestic offshore plant industry, a consensus has been formed regarding the requirement for large offshore basins for performing offshore plant performance verification. Accordingly, the Korea Research Institute of Ships & Ocean Engineering has built the world's largest deep ocean engineering basin (DOEB). The purpose of this study is to evaluate the characteristics of velocity distribution under various conditions of the DOEB. An independent measuring jig is designed and manufactured to measure the current velocities of many locations within a short time. The measurement jig is a 15-m-high triangular-truss structure, and the measurement sensors can move 15 m vertically through an electric motor-wire device. The current speed is measured under various impeller revolutions per minute and locations of the DOEB using the jig. The spatial distribution characteristics of the current velocity in the DOEB and the performance of the current generator are analyzed. The maximum speed is 0.56 m/s in the center of the DOEB water surface, thereby confirming sufficient current velocity distribution uniformity for model testing.

Influence of the Distribution of Wind Velocity and Mist Concentration for the Improvement of Efficiency with an Electrostatic Precipitator (전기집진장치의 효율 개선을 위한 풍속 분포 및 입자농도 분포의 영향)

  • 임헌찬;이덕출
    • Journal of the Korean Society of Safety
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    • v.13 no.4
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    • pp.155-161
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    • 1998
  • Recently, there are widely needs of small scale electrostatic precipitator(ESP) in machine shop and other factories. Since the space of such factories is limited, the improvement of collection efficiency is predominant subject. In this study, we examine the influence of distribution of wind velocity and oil mist concentration inside the ESP in order to improve the performance of the ESP. The distribution of wind velocity and mist concentration is measured respectively in a cross-sectional plane of the ESP. The former is controlled by using a louver which is placed in front of an ionizer and the latter is controlled by lengthening the pipe of entrance of the ESP in order to have plenty of time that mist is dispersed evenly. It is shown that the uniformity of distribution of wind velocity and mist concentration inside the ESP can be getting by adopting a louver with proper shape and lengthening the pipe of entrance and is also contributed to collection efficiency considerably.

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