• Title/Summary/Keyword: Velocity Equation

Search Result 1,812, Processing Time 0.028 seconds

A Study on the Elastic Wave Velocity of Magnetostrictive Materials (자왜 재료의 탄성파 속도에 관한 연구)

  • 강국진;노용래
    • The Journal of the Acoustical Society of Korea
    • /
    • v.20 no.4
    • /
    • pp.54-61
    • /
    • 2001
  • Magnetostrictive materials have nonlinear elasto-magnetic properties. However the constitutive equations to describe the nonlinear properties are not available, yet. In this study we develope the equation in magnetostrictive materials by use of piezomagnetic constitutive equation which is quasi-linearized. With the wave equation, we determine the propagation velocity inside the magnetostrictive materials when a plane wave propagates along a given magnetic field. Validity of the calculated velocity is verified through comparison with experimental velocity measurement results for the most representative magnetostrictive materials. Terfenol-D.

  • PDF

Quadratic Parabolic Equation to Estimate the Vertical Velocity Distribution in the Natural Streamflow (자연하천의 연직방향 유속분포 추정을 위한 포물선식)

  • Park, Seung-Gi;Kim, Tae-Cheol
    • Journal of Korea Water Resources Association
    • /
    • v.33 no.2
    • /
    • pp.169-179
    • /
    • 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 detennined by the relationships to the surface velocity, and a coefficient of the quadratic parabolic equation. The equation was verified to the reserved survey data, and the results were confirmed to be good for the estimation of the characteristics of the vertical velocity distribution. The vertical velocity profile can be applied to calculating the mean velocity and discharge, and to analyse the dispersion of pollutant materials in the streamflow.

  • PDF

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

  • Baek, Kyong Oh
    • Journal of Korea Water Resources Association
    • /
    • v.48 no.4
    • /
    • pp.291-298
    • /
    • 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 Model (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. SKM has presented an analytical solution to the Navier-Stokes equation to describe the transverse variations, and originally been applied to straight and nearly straight compound channel. In order to use SKM in modeling non-prismatic and meandering channels, the shape of cross-section is regarded as a triangle in this study. The analytical solution for the velocity distribution is verified using Manning's equation and applied to velocity data measured at natural streams. Although the velocity equation developed in this study do not agree well with measured data case by case, the equation has a merit that the velocity distribution can be calculated only using geometric data including Manning's roughness coefficient without any measured velocity data.

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
    • /
    • 2000.10a
    • /
    • pp.346-351
    • /
    • 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.

  • PDF

Mean Velocity Distribution of Natural Stream using Entropy Concept in Jeju (엔트로피 개념을 이용한 제주도 상시하천의 평균유속분포 추정)

  • Yang, Se-Chang;Yang, Sung-Kee;Kim, Yong-Suk
    • Journal of Environmental Science International
    • /
    • v.28 no.6
    • /
    • pp.535-544
    • /
    • 2019
  • We computed parameters that affect velocity distribution by applying Chiu's two-dimensional velocity distribution equation based on the theory of entropy probability and acoustic doppler current profiler (ADCP) of Jungmun-stream, Akgeun-stream, and Yeonoe-stream among the nine streams in Jeju Province between July 2011 and June 2015. In addition, velocity and flow were calculated using a surface image velocimeter to evaluate the parameters estimated in the velocity observation section of the streams. The mean error rate of flow based on ADCP velocity data was 16.01% with flow calculated using the conventional depth-averaged velocity conversion factor (0.85), 6.02% with flow calculated using the surface velocity and mean velocity regression factor, and 4.58% with flow calculated using Chiu's two-dimensional velocity distribution equation. If surface velocity by a non-contact velocimeter is calculated as mean velocity, the error rate increases for large streams in the inland areas of Korea. Therefore, flow can be calculated precisely by utilizing the velocity distribution equation that accounts for stream flow characteristics and velocity distribution, instead of the conventional depth-averaged conversion factor (0.85).

Characteristics of Laminar Lifted Flames in Coflow Jet with Various Coflow Velocities (동축류 제트에서 동축류 속도에 따른 층류 부상화염의 특성 연구)

  • Lee, S.J.;Kim, K.N.;Won, S.H.;Chung, S.H.
    • 한국연소학회:학술대회논문집
    • /
    • 2004.06a
    • /
    • pp.21-26
    • /
    • 2004
  • Characteristics of laminar lifted names in coflow jet with various coflow velocities have been studied experimently. USlI1g the fuel nozzle with d=0.254 for the pure propane, liftoff heights are fitted by using power equation with jet velocity. As coflow velocity increases up to 60 cm/s powers of fitting equation steeply decrease. From the result of numerical analysis using the FLUENT, the stoichiometry contour and the axial velocity nondimensionalized by initial jet velocity along the stoichiometry contour are changed with variations of coflow velocities, The change of axial velocity along stoichiometric contour is more sensitive than that of stoichiometric contour, For this reason, powers of fitting equation for liftoff height with jet velocity decreases with the increase of coflow velocity. Using the fuel nozzle with d=4,35 mm for the highly diluted propane by nitrogen, the liftoff height increases with the increase of coflow velocity when coflow velocity is less than the maximum value of initial jet velocity. But when coflow velocity is faster than that, the liftoff height decreases with the increase of coflow velocity.

  • PDF

Evaluation Technique of Concrete Strength Using Impact-Resonance and Combined Method (충격공진법 및 복합법을 이용한 콘크리트의 강도 평가 기법)

  • 이광명;이회근;김동수;김지상
    • Journal of the Korea Concrete Institute
    • /
    • v.11 no.4
    • /
    • pp.157-167
    • /
    • 1999
  • Among several non-destructive testing methods, ultrasonic pulse velocity method and rebound index method have been widely used for the evaluation of concrete strength. However, such methods might not provide accurate estimated results since factors influencing the relationship between strength and either ultrasonic pulse velocity or rebound index are not considered. In this paper, the evaluation method of concrete strength using rod-wave velocity measured by impact-resonance method is proposed. A basic equation is obtained by the linear regression of velocity vs, strength data at specific age and then, aging factor is employed in the equation to consider the difference of the increasing rate between wave velocity and strength. Strengths predicted by the proposed equation agree well with test results. Furthermore, the combined method of rod-wave velocity and rebound index is proposed.

Character for Spatial Distribution of Velocity Using Simple Hydraulic Data (기본적인 수리학적 자료에 의한 유속의 공간적 분포 특성)

  • Koh, Deuk-Koo;Choo, Tai-Ho
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.8 no.6
    • /
    • pp.1560-1565
    • /
    • 2007
  • In this study, Chiu's velocity distribution equation recently developed from the probability and entropy concepts is used to establish a linkage between the mean velocity obtained from the Manning's equation and the corresponding velocity distribution in a channel cross section. The linkage to be established enables computing the velocity distribution along with the mean velocity, from simple hydraulic data such as Manning's n, hydraulic radius and channel slope irrespective of including sediment or not.

  • PDF

The Estimation of Friction Velocity by Hydraulic Parameters Reflecting Turbulent Flow Characteristics in a Smooth Pipe Line (매끄러운 관수로 내 난류흐름특성을 반영한 수리학적 매개변수에 의한 마찰속도의 산정)

  • Choo, Tai Ho;Son, Jong Keun;Kwon, Yong Been;Ahn, Si Hyung;Yun, Gwan Seon
    • The Journal of the Korea Contents Association
    • /
    • v.16 no.4
    • /
    • pp.614-623
    • /
    • 2016
  • Grid(pipe network) design is an important element of Smart Water Grid, which essential to estimate hydraulic parameters such as the pressure, friction factor, friction velocity, head loss and energy slope. Especially, friction velocity in a grid is an important factor in conjunction with energy gradient, friction coefficient, pressure and head loss. However, accurate estimation friction head loss, friction velocity and friction factor are very difficult. The empirical friction factor is still estimated by using theory and equation which were developed one hundred years ago. Therefore, in this paper, new equation from maximum velocity and friction velocity is developed by using integration relationship between Darcy-Weisbach's friction head loss equation and Schlichting equation and regression analysis. To prove the developed equation, smooth pipe data areis used. Proposed equation shows high accuracy compared to observed data. Study results are expected to be used in stability improvements and design in a grid.

Evaluation of Concrete Strength Using Compression Wave Velocity (압축파 속도를 이용한 콘크리트의 강도 평가)

  • 이회근;이광명;김동수;김지상
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 1999.04a
    • /
    • pp.697-702
    • /
    • 1999
  • Among several non-destructive testing methods, ultrasonic pulse velocity method has been widely used for the evaluation of concrete strength. However, this method might not provide accurate estimated results since factors influencing the relationship between strength and wave velocity is not considered. In this study, the evaluation methods of concrete strength using compression wave velocities measured by either ultrasonic pulse velocity method or impact-resonance method are proposed. A basic equation is obtained by the linear regression with velocity vs. strength data at a specific age and then, ageing factor is employed in the equation to consider the difference of the increasing rate between wave velocity and strength. Strengths predicted by the proposed equation agree well with test results.

  • PDF