• Title/Summary/Keyword: Residual flow

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A Study of Distribution of Jellyfish by Particle Numerical Experiment in Masan Bay (마산만에서 입자수치실험에 의한 해파리 분포연구)

  • Choi, Min-Ho;Ryu, Tai-Gwan;Kim, Dong-Sun
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.22 no.4
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    • pp.335-343
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    • 2016
  • The spatio-temporal distribution of jellyfish in Masan Bay was investigated in this study using a numerical model. First, a three-dimensional hydrodynamic model (POM) was constructed,taking into account residual flows, tides, temperature, salinity, and wind effects. A particle tracking model based on residual flow was then used to investigate the jellyfish present in Masan Port, referred to as the Heavy Industry and Gapo New Port in Masan. Jellyfish distribution was concentrated with maximum (2,533 individual) in the North Sea near Machang Bridge. Itcan be concluded that this concentration was due to multi-directional residual flows and topography effects. Residual flow currents are a dominant factor in understanding the aggregation of jellyfish, and this study used a numerical simulation of tide-induced residual currents, wind-driven currents and density currents in distinct cases to thoroughly address the topic. As a result, wind-driven currents (effect of the wind) was found to be superior to other components as an influence on the distribution of jellyfish near Machang Bridge and Modo in Masan Bay.

The Characteristics of Tidal Residual Current in Youngil Bay (영일만의 조석잔차류 거동 특성)

  • Kim Jong-Kyu
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.4 no.1
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    • pp.14-23
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    • 2001
  • The characteristics of tidal circulation with Hyungsan River discharges in Youngil Bay by the numerical experiments is elucidated. For the simulation of tidal residual currents related to inflow by the river discharges in Youngil Bay located in the southeastern part of Korean Peninsula, the two-dimensional numerical experiment is peformed. The tidal elevation boundary conditions of the 4 main tidal harmonic constituents (M₂, S₂, K₁ and O₁) on the open boundary and river discharges at the river boundary are considered. The computed results obtained from numerical experiment showed good agreements with the field observation ones. The residual currents generally flow toward the inner bay through the western (Dalman-Gap) and central areas of the bay, and then the currents go toward the outer bay along the eastern shore (Changgi-Gap) of the bay with anti-clockwise circulation. Especially, in the numerical experiment without Hyungsan River discharges, these flow patterns are disappeared. Based on the results, it showed that the Hyungsan River discharges play the dominant role in the patterns of tidal residual currents. This flow pattern of tidal residual currents are important mechanism of water quality, material transport in Youngil Bay.

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Measurement of Residual Stress Distribution in Injection-Molded Short Fiber Composites (단섬유 복합재료 사출성형물의 잔류응력 측정)

  • 김상균;이석원;윤재륜
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2001.10a
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    • pp.61-63
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    • 2001
  • Residual stress distribution in injection-molded short fiber composites was determined using layer-removal method. Polysterene with 3 vol% carbon fibers was injection-molded into the tensile specimen. With milling machine layer-removal process was conducted and the curvature data were acquired. Treuting and Read analysis which is assuming isotropic material, and White analysis considering anisotropy due to the fiber orientation were used to calculate residual stress of the flow direction through the thickness direction and compared with each other.

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Infiltration Characteristics for Unsaturated Residual Soil (화강풍화토의 불포화 침투특성에 관한 연구)

  • 김영욱;김도형;성상규;이인모
    • Proceedings of the Korean Geotechical Society Conference
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    • 2001.03a
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    • pp.147-152
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    • 2001
  • This study investigated one-dimensional vertical infiltration to an unsaturated residual soil by numerical solutions, FDM. In order to estimate the parameters needed for numerical analysis, tire soil-water characteristic curve(SWCC) of Shinnae-dong soil, one of the most typical residual soils in Korea, were experimentally obtained. Then, the statistical analysis for obtaining the SWCC was performed. The numerical solution to the linearized governing equation for unsaturated groundwater flow provides the infiltration characteristics for the unsaturated residual soil represented by transient pressure profiles and water contents profiles.

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A Study of a Simultaneous Filling and Solidification During Casting Process (충전과 상변화 현상을 포함한 주조과정에 대한 연구)

  • Im, lk-Tae;Kim, Woo-Seung
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.23 no.8
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    • pp.987-996
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    • 1999
  • An algorithm for modeling the filling of metal into a mold and solidification has been developed. This algorithm uses the implicit VOF method for a filling and a general implicit source-based method for solidification. The model for simultaneous filling and solidification is applied to the two-dimensional filling and solidification of a square cavity. The effects of the wall temperature and gate position on the solidification are examined. The mixed natural convection flow and residual flow resulting from the completion of a filling are included in this study to investigate the coupled effects of the filling and natural convection on solidification. Two different filling configurations (assisting flow and opposite flow due to the gate position) are analysed to study the effects of residual flow on solidification. The results clearly show the necessity to carry out a coupled filling and solidification analysis including the effect of natural convection.

An Effect of Wind on Circulation in Kamak Bay (가막만의 해수유동에 미치는 바람의 영향)

  • PARK Sung-Eun;CHO Kyu-Dae;HONG Chul-Hoon;KIM Dong-Sun;CHO Kwang-Woo
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.32 no.5
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    • pp.674-679
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    • 1999
  • The effect of wind on the circulation in Kamak Bay in the southern sea of Korea was examined using a numerical shallow water model. The experiments were primarily focused on how the effect of wind influence the tidal residual current. According to wind directions, the residual currents were changed; the westerly wind created a strong anti-clockwise eddy in the northwestern area of the bay where the flow field is usually very weak; the easterly wind strengthened the flow field in the central area of the bay; the patterns of flow fields to the north and south winds were almost the same as one without the wind, although the flow field became slightly stronger, The model flirty reproduced features in the observed current field at Pyongsa.

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CHARACTERIZATIONS ON CHAIN RECURRENCES

  • Park, Jong-Suh;Ku, Se-Hyun
    • Bulletin of the Korean Mathematical Society
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    • v.47 no.2
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    • pp.287-293
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    • 2010
  • It is well known that there is a residual subset J of the space of $C^1$-diffeomorphisms on a compact Riemannian manifold M such that the maps f $\mapsto$ chain recurrent set of f and f $\mapsto$ number of chain components of f are continuous on J. In this paper we get the flow version of the above results on diffeomorphisms.

Effect of Value Timing on Residual Gas Fraction and Combustion Characteristics at Part Load Condition in an SI Engine (가솔린 엔진의 밸브타이밍 변화가 부분부하 조건에서 잔류가스량 및 연소특성에 미치는 영향)

  • 김철수;송해박;이종화;유재석;조한승
    • Transactions of the Korean Society of Automotive Engineers
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    • v.8 no.4
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    • pp.26-33
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    • 2000
  • In-cylinde flow and mixture formation are key contributors to both idle stability and combustion stability at part load condition in SI engine. The real time measurements of air-fuel ration and in- cylinder residual gas fraction are particularly important to obtain a better understanding of the mechanisms for combustion and emissions especially during cold start and throttle transient condition. This paper reports the cycle resolved measurements of residual gas fraction and equivalence ration near speak plug with value timing change and their effects on combustion characteristics at part load. The results showed that the effect of intake value opening on the residual gas fraction was smaller than that of exhaust valve closing because of the decreases of exhaust gas reverse flow from exhaust port. The variation of equivalence ratio near spark plug increased with the increase of value overlap and it closely related with heat release rate and combustion stability

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Numerical Analysis of Residual Stresses and Birefringence in Injection/Compression Molded Center-gated Disks (II) - Effects of Processing Conditions - (사출/압축 성형 Center-gated 터스크에서의 잔류 응력과 복굴절의 수치 해석 (II) - 공정조건의 영향 -)

  • Lee, Young-Bok;Kwon, Tai-Hun;Yoon, Kyung-Hwan
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.11
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    • pp.2355-2363
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    • 2002
  • The accompanying paper, Part 1, has presented the physical modeling and basic numerical analysis results of both the flow-induced and thermally-induced residual stress and birefringence in injection molded center gated disks. The present paper, Part II, has attempted to investigate the effects of various processing conditions of injection/compression molding process on the residual stress and birefringence. The birefringence is significantly affected by injection melt temperature, packing pressure and packing time. Birefringence in the shell layer increases as melt temperature gets lower. The inner peak of birefringence increases with packing time and packing pressure. On the other hand, packing pressure, packing time and mold wall temperature affect the thermally-induced residual stress rather significantly in the shell layer, but insignificantly in the core region. Injection/compression molding has been found to reduce the birefringence in comparison with the conventional injection molding process. In particular, mold closing velocity and initial opening thickness in the compression stage of injection/compression molding process have significant effect on the flow-induced birefringence, but not on tile thermal residual stress and the thermally induced birefringence.

FLOW CHARACTERISTICS OF A SYSTEM WHICH HAS TWO PARALLEL PUMPS (두 대의 펌프가 병렬로 설치된 장치의 유량 특성)

  • Park, J.G.;Park, J.H.;Park, Y.C.
    • Journal of computational fluids engineering
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    • v.17 no.4
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    • pp.1-8
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    • 2012
  • During a reactor normal operation, two parallel 50% capacity cooling pumps circulate primary coolant to remove the fission reaction heat of the reactor through heat exchangers cold by a cooling tower. When one pump is failure, the other pump shall continuously circulate the coolant to remove the residual heat generated by the fuels loaded in the reactor after reactor shutdown. It is necessary to estimate how much flow rate will be supplied to remove the residual heat. We carried out a flow network analysis for the parallel primary pumps based on the piping network of the primary cooling system in HANARO. As result, it is estimated that the flow rate of one pump increased about 1.33 times the rated flow of one pump and was maintained within the limit of the cavitation critical flow.