• Title/Summary/Keyword: Three-Dimensional Reynolds-Averaged Navier-Stokes Equation

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3-D Incompressible Viscous Flow Analysis Around A Rotor-Stator with Rotor-Stator Interaction (로터-스테이터 상호작용을 고려한 3차원 유동 해석)

  • Kim K. H.;Jung Y. L.;Park W. G.;Lee S. W.
    • 한국전산유체공학회:학술대회논문집
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    • 2000.05a
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    • pp.78-83
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    • 2000
  • An iterative time marching procedure for solving incompressible internal flow has been applied to the flow around a rotor-stator. This procedure solves three-dimensional incompressible Reynolds-averaged Navier-Stokes equation on a moving, time-deforming, non-orthogonal body-fitted grid using second-order accurate schemes for the time derivatives and third/second-order accurate schemes for the spatial derivatives. To handle rotationg geometry, the multiblock technique is applied and the overall flow domain is subdivided into two blocks. In each block, a grid is generated and flowfield is solved independently of the other blocks. The boundary data for each block is provided by the neighboring blocks using bilinear interpolation technique.

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Investigation on Performance Characteristics of Dual Vertical Axis Turbine of 100 kW Class Tidal Energy Convertor (100 kW급 조류발전용 듀얼 수직축 터빈의 성능특성 연구)

  • HEO, MAN-WOONG;KIM, DONG-HWAN;PARK, JIN-SOON
    • Journal of Hydrogen and New Energy
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    • v.31 no.1
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    • pp.151-159
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    • 2020
  • This study aimed to investigate the performance characteristics of vertical axis turbine of tidal energy convertor. Three-dimensional Reynolds-averaged Navier-Stokes equation with shear stress transport turbulence model has been solved to analyze the fluid flow of the vertical axis turbine. The hexahedral grids have been used to construct the computational domain and the grid dependency test has been performed to find the optimum grid system. Four steps have been carried out to design the vertical axis turbine of the 100 kW class tidal energy convertor.

Analysis of Flow through High Pressure Bypass Valve in Power Plant (발전소용 고압 바이패스 밸브의 유동해석)

  • Cho, An-Tae;Kim, Kwang-Yong
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2558-2562
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    • 2007
  • In the present work, flow characteristics analysis has been performed for steam turbine bypass control valve (single-path type). The numerical analysis is performed by solving three-dimensional Reynolds-averaged Navier-Stokes (RANS) equations. Shear stress transport (SST) model is used as turbulence closure. Symmetry condition is applied at the mid plane of the valve while adiabatic condition is used at the outer wall of the cage. Grid independency test is performed to find the optimal number of grid points. The pressure and temperature distributions on the outer wall of the cage are analyzed. Mass flow rate at maximum plug opening condition is compared with the designed mass flow rate.

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ANALYSIS OF TURBULENT HEAT TRANSFER FROM STAGGERED PIN-FIN ARRAYS WITH DIAMOND SHAPED ELEMENTS AT VARIOUS GEOMETRICAL CONFIGURATIONS (엇갈린 다이아몬드형 핀휜의 형상에 따른 난류열전달 성능해석)

  • Cho, A.T.;Kim, K.Y.
    • Journal of computational fluids engineering
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    • v.13 no.2
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    • pp.20-26
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    • 2008
  • A numerical study is carried out to analyze the steady three-dimensional turbulent flow and convective heat transfer in a staggered pin-fin array with diamond shaped elements at various geometrical configurations. Steady Reynolds-averaged Navier-Stokes equations and energy equation are solved using a finite volume based solver. Shear stress transport (SST) model is used as turbulence closure. The computational domain is composed of one pitch of pin-fin displacement with periodic boundary conditions on the surfaces normal to the streamwise direction and the cross-streamwise direction. The numerical results for Nusselt number and friction factor are validated with experimental results. The effects of pin angle, pin height and pitch on Nusselt number, friction factor and efficiency index are investigated.

Numerical Optimization of the Shape of Mixing Vane in Nuclear Fuel Assembly (핵연료 집합체 혼합날개형상의 수치최적설계)

  • Seo Jun-Woo;Kim Kwang-Yong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.8 s.227
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    • pp.929-936
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    • 2004
  • In the present work, shape of the mixing vane in Plus7 fuel assembly has been optimized numerically using three-dimensional Reynolds-averaged Navier-Stokes analysis of flow and heat transfer. Standard $k-{\epsilon}$ model is used as a turbulence closure. The Response surface method is employed as an optimization technique. The objective function is defined as a combination of heat transfer rate and inverse of friction loss. Bend angle and base length of mixing vane are selected as design variables. Thermal-hydraulic performances for different shapes of mixing vane have been discussed, and optimum shape has been obtained as a function of weighting factor in the objective function.

Numerical analysis of 3-dimensional buoyant turbulent flow in a stairwell model with three different finite differencing schemes (유한차분 도식에 따른 건물 계단통에서의 3차원 부력 난류유동 수치해석)

  • Myong, H.K.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.11 no.1
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    • pp.73-80
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    • 1999
  • This paper describes a numerical study of three-dimensional buoyant turbulent flow in a stairwell model with three convective differencing schemes, which include the upwind differencing scheme, the hybrid scheme and QUICK scheme. The Reynolds-averaged Navier-Stokes and energy equations are solved with a two-equation turbulence model. The Boussinesq approximation is used to model buoyancy terms in the governing equations. Three-dimensional predictions of the velocity and temperature fields are presented and are compared with experimental data. Three-dimensional simulations with each scheme have predicted the overall features of the flow fairly satisfactorily. A better agreement with experimental is achieved with QUICK scheme.

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Numerical Optimization of A Multi-Blades Centrifugal Fan For High-Efficiency Design (원심다익송풍기의 고효율 설계를 위한 수치최적설계)

  • Seo, Seoung-Jin;Kim, Kwang-Yong
    • 유체기계공업학회:학술대회논문집
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    • 2003.12a
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    • pp.385-390
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    • 2003
  • Shape of a multi-blades centrifugal fan is optimized by response surface method based on three-dimensional Navier-Stokes analysis. For numerical analysis, Reynolds-averaged Wavier-Stokes equations with standard $k-{\varepsilon}$ turbulence model are transformed into non-orthogonal curvilinear coordinate system, and are discretized with finite volume approximations. Due to the large number of blades in this centrifugal fan, the flow inside of the fan is regarded as steady flow by introducing the impeller force models for economic calculations. Optimizations with and without constraints are carried out. Design variables, location of cur off, radius of cut off, expansion angle of scroll and width of impeller were selected to optimize the shapes of scroll and blades. Data points for response evaluations were selected by D-optimal design, and linear programming method was used for the optimization on the response surface. As a main result of the optimization, the efficiency was successfully improved. The correlation of efficiency with relative size of inactive zone at the exit of impeller is discussed as well as with average momentum fluxes in the scroll.

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Free Surface Flow in a Trench Channel Using 3-D Finite Volume Method

  • Lee, Kil-Seong;Park, Ki-Doo;Oh, Jin-Ho
    • Journal of Korea Water Resources Association
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    • v.44 no.6
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    • pp.429-438
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    • 2011
  • In order to simulate a free surface flow in a trench channel, a three-dimensional incompressible unsteady Reynolds-averaged Navier-Stokes (RANS) equations are closed with the ${\kappa}-{\epsilon}$ model. The artificial compressibility (AC) method is used. Because the pressure fields can be coupled directly with the velocity fields, the incompressible Navier-Stokes (INS) equations can be solved for the unknown variables such as velocity components and pressure. The governing equations are discretized in a conservation form using a second order accurate finite volume method on non-staggered grids. In order to prevent the oscillatory behavior of computed solutions known as odd-even decoupling, an artificial dissipation using the flux-difference splitting upwind scheme is applied. To enhance the efficiency and robustness of the numerical algorithm, the implicit method of the Beam and Warming method is employed. The treatment of the free surface, so-called interface-tracking method, is proposed using the free surface evolution equation and the kinematic free surface boundary conditions at the free surface instead of the dynamic free surface boundary condition. AC method in this paper can be applied only to the hydrodynamic pressure using the decomposition into hydrostatic pressure and hydrodynamic pressure components. In this study, the boundary-fitted grids are used and advanced each time the free surface moved. The accuracy of our RANS solver is compared with the laboratory experimental and numerical data for a fully turbulent shallow-water trench flow. The algorithm yields practically identical velocity profiles that are in good overall agreement with the laboratory experimental measurement for the turbulent flow.

Directional Wave Generation in the Navier-Stokes Equations Using the Internal Wave Maker (Navier-Stokes 방정식 모형의 경사지게 입사하는 파랑 내부조파)

  • Ha, Tae-Min;NamGung, Don;Cho, Yong-Sik
    • Journal of Korea Water Resources Association
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    • v.45 no.6
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    • pp.545-555
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    • 2012
  • A numerical modeling has become increasingly popular and more important to the study of water waves with a rapid advancement of computer technology. However, different types of problems are induced during simulating wave motion. One of the key problems is re-reflection to a computation domain at the incident boundary. The internal wave generating-absorbing boundary conditions have been commonly used in numerical wave models to prevent re-reflection. For the Navier-Stokes equations model, the internal wave maker using a mass source function of the continuity equation has been used to generate various types of waves. Nonetheless, almost every numerical experiment is performed in two dimensions and only a few tests have been expanded to three dimensions. More recently, a momentum source function of the Boussinesq equations is applied to generate essentially directional waves in the three dimensional Navier-Stokes equations model. In this study, the internal wave maker using a momentum source function is employed to generate targeted linear waves in the three-dimensional LES model.

Analysis of the flood Characteristics in the Woo-Ee Stream Using FLOW-3D (FLOW-3D를 이용한 우이천의 홍수특성 분석)

  • Yoon, Sun-Kwon;Moon, Young-Il;Kim, Jong-Suk;Oh, Keun-Taek;Lee, Su-Gon
    • 한국방재학회:학술대회논문집
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    • 2007.02a
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    • pp.603-607
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    • 2007
  • Recently, the frequency of unexpecting heavy rains has been increased due to abnormal climate and extreme rainfall. There was a limit to analyze one dimension or two dimension stream flow of domestic rivers that was applied simple momentum equation and fixed energy conservation. Therefore, hydrodynamics flow analysis in rivers has been needed three dimensional numerical analysis for correct stream flow interpolation. In this study, CFD model on FLOW-3D was applied to stream flow analysis, which solves three dimension RANS(Reynolds Averaged Navier-Stokes Equation) control equation to find out physical behavior and the effect of hydraulic structures. Numerical simulation accomplished those results was compared by using turbulence models such as $k-{\backepsilon}$, RNG $k-{\backepsilon}$ and LES. Those numerical analysis results have been illustrated to bends and junctions by the turbulence energy effects, velocity of flow distributions, water level pressure distributions and eddy flows.

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