• Title/Summary/Keyword: Velocity Potential

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Wave Friction Factor far Rough Turbulent Flow (전난류에서의 파마찰계수)

  • 유동훈
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.5 no.2
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    • pp.51-57
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    • 1993
  • It is often assumed that the wave velocity at the bottom given by potential wave theory il the same as the wave velocity at the top of the turbulent boundary layer. This assumption is found to be the major cause of the error detected by recent elaborate theories and numerical models for the description of velocity profile near the sea bottom. A relationship is suggested between the potential velocity and the real boundary velocity. Based on this relation, the existing theories of Jonsson (1967) and Fredsoe (1984) are refined for the estimation of wave friction factor, and the computation results of the modified theories are favourably compared with the published laboratory results.

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Simulation of Nonlinear Water Waves using Boundary Element Method (경계요소법을 이용한 비선형파의 재현)

  • 오영민;이길성;전인식
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.5 no.3
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    • pp.204-211
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    • 1993
  • Boundary element method is applied to simulate nonlinear water waves using Green's identity formula in a numerical wave flume. A system of linear equations is formulated from the governing equation and free surface boundary conditions in order to calculate velocity potential and water surface elevation at each nodal point. The velocity square terms are included in the dynamic free surface boundary condition. The free surface is treated as a moving boundary. the vertical variation of velocity potential being considered in calculating the time derivative of the velocity potential at the free surface. The present method is applied to simulate solitary wave and Stokes 2nd order wave, and shows excellent agreements with their theoretical values.

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VELOCITY ANALYSIS OF M13 BY MAXIMUM LIKELIHOOD METHOD

  • Oh, K.S.;Lin, D. N. C.
    • Journal of The Korean Astronomical Society
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    • v.25 no.1
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    • pp.1-9
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    • 1992
  • We present new approach to analysis of velocity data of globular clusters. Maximum likelihood method is applied to get model parameters such as central potential, anisotropy radius, and total mass fractions in each mass class. This method can avoid problems in conventional binning method of chi-square. We utilize three velocity components, one from line of sight radial velocity and two from proper motion data. In our simplified scheme we adopt 3 mass-component model with unseen high mass stars, intermediate visible stars, and low mass dark remnants. Likelihood values are obtained for 124 stars in M13 for various model parameters. Our preferred model shows central potential of $W_o=7$ and anisotropy radius with 7 core radius. And it suggests non-negligible amount of unseen high mass stars and considerable amount of dark remnants in M13.

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Experimental Studies on Risks of BB Pellets Using Gelatine Based Simulants (젤라틴 Simulant를 이용한 비비탄총 탄환의 위험성에 관한 실험적 연구)

  • Park, Dal-Jae;Kim, Hyung-Suk;Lee, Young-Soon
    • Journal of the Korean Society of Safety
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    • v.26 no.3
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    • pp.29-33
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    • 2011
  • Experimental studies were performed to investigate the injury potential of BB pellets through gelatine based simulants. In order to record BB pellet movements penetrating into the target simulant, a high-speed video camera was used. In this study the first investigation involved the effects on concentrations, homogeneity and gelation times of the gelatine simulant. The second investigation involved the penetration depth of the pellets to the simulant by different distances between the BB gun and the simulant. The final one is associated with impact velocity, threshold velocity and penetration depth of the pellets by different kinetic energies of the BB gun. Results provided the basis in assessing the injury potential of BB pellets.

A Study on the Propogation Velocity of Biological Action Potential (생체의 자극 전도속도에 관한 연구)

  • Che, Gyu-Shik;Kwon, Yong-Chan
    • Journal of Advanced Navigation Technology
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    • v.14 no.6
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    • pp.1002-1009
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    • 2010
  • I made the axon to the electrical transmission model and then constructed electrical equivalent model using Kirhhoff's current law and voltage law in this paper. I calculated various axon parameters in order to analyze the electrical potential hehavior versus minute distance chang of axon. The transmission velocity of unmyelinated nerve is proportional to square root of axon diameter, while that of myelinated nerve is directly proportional to its diameter. Because the transmission of myelin sheath is independent of voltage unlike unmyelinated sheath, the Hodgkin-Huxley model across the membrane is not so precise.

Hydrodynamic Behavior Analysis of Vertical-Cylindrical Liquid-Storge Tanks by Mathematically Analytic Method (수학적 해석 방법에 의한 액체저장탱크의 액동압 거동 해석)

  • Park, Jong-Ryul;Oh, Taek-Yul
    • Proceedings of the KSME Conference
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    • 2001.06a
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    • pp.628-635
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    • 2001
  • Hydrodynamic behavior and response of vertical-cylindrical liquid-storage tank is considered. The equation of the liquid motion is shown by Laplace's differential equation with the fluid velocity potential. The solution of the Laplace's differential equation of the liquid motion is expressed with the modified Bessel functions. Only rigid tank is studied. The effective masses and heights for the tank contents are presented for engineering design model.

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COMPUTATION OF ADDED MASS AND DAMPING COEFFICIENTS DUE TO A HEAVING CYLINDER

  • Bhatta Dambaru D.
    • Journal of applied mathematics & informatics
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    • v.23 no.1_2
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    • pp.127-140
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    • 2007
  • We present the boundary value problem (BVP) for the heave motion due to a vertical circular cylinder in water of finite depth. The BVP is presented in terms of velocity potential function. The velocity potential is obtained by considering two regions, namely, interior region and exterior region. The solutions for these two regions are obtained by the method of separation of variables. The analytical expressions for the hydrodynamic coefficients are derived. Computational results are presented for various depth to radius and draft to radius ratios.

High Velocity Compaction : Overview of Materials, Applications and Potential

  • Dore, Florence;Lazzarotto, Ludovic;Bourdin, Stephane
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.20-21
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    • 2006
  • Through different projects, CETIM and its scientific and industrial partners have evaluated the potential of the High Velocityy Compaction Technology in terms of materials and component shape. Various kinds of powder materials were studied: metals, ceramics and polymers. The HVC process was used with success to manufacture gears, large parts and multilevel components. Due to the high density of HVC parts, the green machining process enables shapes to be produced that would otherwise be impossible to compact and components to be produced with very hard sintered and homogeneous materials.

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ON THE POTENTIAL OF A ROTATING BAR OF REGULAR GALAXIES

  • SHAMSHIEV FAZILIDDIN T.
    • Journal of The Korean Astronomical Society
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    • v.29 no.spc1
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    • pp.73-74
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    • 1996
  • This paper deals with steady-state gravitational potentials of nonaxisymmetric three dimensional systems which rotate with a constant angular velocity. For these systems a class of potentials with local integrals has been found.

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An Investigation of the Fundamental Combustion Characteristics for the Utilization of LFG (LFG 활용을 위한 기초 연소특성 검토)

  • Lee, Chang-Eon;Oh, Chang-Bo;Kum, Sung-Min
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.1
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    • pp.99-108
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    • 2004
  • Fundamental combustion characteristics, such as the combustion potential, burning velocity and flame stability, for the practical utilization of LFG(Landfill gas) and LFG-blended fuels were experimentally investigated. The combustion potentials(CP) of LFG-blended fuels calculated from the previously suggested formulae were compared with burning velocities obtained by present experiments. The results showed that the previous formulae fur CP of LFG-blended fuels were not agreed with the experimental burning velocity, and these formulae should be revised. To provide an useful information needed to design the combustion devices, a triangular diagram was suggested for the maximum burning velocity of the mixture of CH$_4$, LPG and LFG. From the investigation of the burning velocity and the flame stability in a practical combustor, it was noted that the LFG-blended fuels, of which heating values or Wobbe indices were adjusted to that of natural gas, could be used as an alternative fuel of natural gas.