• Title/Summary/Keyword: Turbulent Flows

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Computation of Turbulent Flows in Swirl Combustor (동축의 선회류들이 배합되는 연소기내 난류유동의 수치해석)

  • 백석철;김광용
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.10 no.4
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    • pp.511-518
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    • 1986
  • 본 연구에서는 난류모델로는 기존의 K-.epsilon.모델과 LPS방법으로 수정된 K-.epsilon. 모 델을, 수치적 Scheme으로는 Hybrid Difference Scheme과 Skew-upwind Difference Sc- heme을 사용하여 그 결과를 각각 비교하였다.

Analytical Solution for Hypersonic Flow on Blunt Bodies (뭉뚝한 물체 주변에 형성된 극초음속유동해석)

  • Baik Doo Sung
    • Journal of computational fluids engineering
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    • v.8 no.4
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    • pp.1-5
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    • 2003
  • A Thin-layer Wavier-Stokes equations are applied for the hypersonic flow over blunt bodies with applications to laminar as well as turbulent flows. The equations are expressed in the forms of flux-vector splitting and explicit algorithm. The upwind schemes of Steger-Warming and Van Leer are investigated to predict accurately the heating loads along the surface of the body. A mixed scheme has been presented for the differencing the convective terms and the mixed scheme is found to be less dissipative producing accurate solutions.

A Numerical Simulation of Flows in an Engine Cooling Passage (엔진 냉각유로 내의 유동에 관한 수치해석)

  • 허남건;윤성영;조원국;김광호
    • Transactions of the Korean Society of Automotive Engineers
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    • v.1 no.1
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    • pp.32-40
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    • 1993
  • Flow fields in model engine cooling passages are studied numerically by using TURBO-3D program, a finite volume based 3-D turbulent flow program adopting a general body fitted coordinate system. The effects of exit position on mass flow rate at each gasket hole are examined for a model cooling passage in order to understand the flow distribution inside the water jacket. The results of the present study can be applied to the design of high performance, high reliability engine.

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Turbulence effects on surface pressures of rectangular cylinders

  • Li, Q.S.;Melbourne, W.H.
    • Wind and Structures
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    • v.2 no.4
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    • pp.253-266
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    • 1999
  • This paper presents the effects of free-stream turbulence on streamwise surface pressure fluctuations on two-dimensional rectangular cylinders. Particular attention is given to possible effects of turbulence integral scale on fluctuation and peak pressures. The mean, standard deviation, peak pressure coefficients, spectra and cross-correlation of fluctuating pressures were measured to investigate the nature of the separation and reattachment phenomenon in turbulent flows over a wide range of turbulence intensity and integral scale.

Development of Euler/Navier-Stokes Solver using Chimera Grid Method (Chimera 격자계를 이용한 Euler/Navier-Stokes Solver의 개발)

  • Lee S.;Park M.;Cho K. W.;Kwon J. H.
    • 한국전산유체공학회:학술대회논문집
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    • 1998.11a
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    • pp.141-146
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    • 1998
  • An Euler/Navier Stokes solver has been developed for the analysis of steady and unsteady flows. The $q-{\omega}$ turbulent model has been incorporated into the solver in strongly coupled manner for stability and robustness. A new Chimera hole cutting algorithm, Cut-paste algorithm, has been devised for automatic Chimera hole cutting. Number of viscous/inviscid numerical computations demonstrate the accuracy and the versatility of the solver.

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Direct Solving the Boltzmann Equation for Supersonic Jet Problems with Instabilities

  • Aristov V.V.;Zabelok S.A.
    • 한국전산유체공학회:학술대회논문집
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    • 2003.10a
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    • pp.268-269
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    • 2003
  • The Boltzmann kinetic equation is solved directly by means of the conservative splitting method. Underexpanded supersonic free jet flows with small Knudsen numbers are studied. In this numerical simulation features intrinsic to appropriate experiments are observed. Streamwise vortices in a mixing layer and chaotic downstream temporal-spatial fluctuations of microscopic quantities with large amplitude are obtained.

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A Study on the model of Thermal Plume Flow in the Forest Fire (산불에 의한 열적상승유동 해석에 관한 연구)

  • Ji, Young-Moo;Park, Jung-Sang
    • 한국전산유체공학회:학술대회논문집
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    • 2008.03b
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    • pp.358-361
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    • 2008
  • A study is made of thermal plume flow model for the development of helicopter simulator over the forest fire. For numerical analysis, the Boussinesq fluid approximation and line fire model, which is assumed by the shape of forest fire spreading, are adopted. Comparing 3-D full numerical solutions with 2-D similarity solution, it has been built a new model that is capable of temperature prediction along the symmetric vertical axis in both cases of laminar and turbulent flows.

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FDF-based analysis of nonlinear combustion instability in the lean premixed combustor (FDF를 이용한 메탄 희박 예혼합 연소기의 비선형 열음향학적 불안정성 해석)

  • Oh, Seungtaek;Shin, Yungjun;Kim, Yongmo
    • 한국연소학회:학술대회논문집
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    • 2015.12a
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    • pp.115-116
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    • 2015
  • In the present approach, the flame-acoustics interaction is represented by FDF (Flame Describing Function) which is a important source term in the Helmholtz' equation. In this study, the combustion instability is analyzed by the forced mode strategy with the measured FDF. Numerical results indicate that the present approach reasonably well predicts the essential features of the combustion instability characteristics in the lean premixed combustor under the gas-turbine like environment.

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Comparison of Numerical Results for Laminar Wavy Liquid Film Flows down a Vertical Plate for Various Time-Differencing Schemes for the Volume Fraction Equation (수직평판을 타고 흐르는 층류파동액막류에 대한 체적분율식 시간차분법에 따른 해석 결과 비교)

  • Park, Il-Seouk;Kim, Young-Jo;Min, June-Kee
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.35 no.11
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    • pp.1169-1176
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    • 2011
  • Liquid film flows are classified into waveless laminar, wavy laminar, and turbulent flows depending on the Reynolds number or the flow stability. Since the wavy motions of the film flows are so intricate and nonlinear, studies on them have largely been experimental. Most numerical approaches have been limited to the waveless flow regime. The various free surface-tracking schemes adopted for this problem were used to more accurately estimate the average film thickness, rather than to capture the unsteady wavy motion. In this study, the wavy motions in laminar wavy liquid film flows with Reynolds numbers of 200-1000 were simulated with various numerical schemes based on the volume of fluid (VOF) method for interface tracking. The results from each numerical scheme were compared with the experimental results in terms of the average film thickness, the wave velocity, and the wave amplitude.