• Title/Summary/Keyword: Non-staggered Grid

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A Study of Non-staggered Grid Approach for Incompressible Heat and Fluid Flow Analysis (비압축성 열유동 해석을 위한 비엇갈림 격자법에 대한 연구)

  • Kim Jongtae;Kim Sang-Baik;Kim Hee-Dong;Maeng Joo-sung
    • Journal of computational fluids engineering
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    • v.7 no.1
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    • pp.10-19
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    • 2002
  • The non-staggered(collocated) grid approach in which all the solution variables are located at the centers of control volumes is very popular for incompressible flow analyses because of its numerical efficiency on the curvilinear or unstructured grids. Rhie and Chow's paper is the first in using non-staggered grid method for SIMPLE algorithm, where pressure weighted interpolation was used to prevent decoupling of pressure and velocity. But it has been known that this non-staggered grid method has stability problems when pressure fields are nonlinear like in natural convection flows. Also Rhie-Chow scheme generates large numerical diffusion near curved walls. The cause of these unwanted problems is too large pressure damping term compared to the magnitude of face velocity. In this study the magnitude of pressure damping term of Rhie-Chow's method is limited to 1∼10% of face velocity to prevent physically unreasonable solutions. The wall pressure extrapolation which is necessary for cell-centered FVM is another source of numerical errors. Some methods are applied in a unstructured FV solver and analyzed in view of numerical accuracy. Here, two natural convection problems are solved to check the effect of the Rhie-Chow's method on numerical stability. And numerical diffusion from Rhie-Chow's method is studied by solving the inviscid flow around a circular cylinder.

Analysis of the Flow in Square Cavity Using CIP Method in Non-staggered Grid Arrangement (비엇갈림 격자계에서 CIP법을 이용한 캐비티내의 유동해석)

  • Lee, Jung-Hee;Kang, Joon;Im, Do-Kiun;Kim, Charn-Jung
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.1821-1826
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    • 2003
  • In this study, we discuss CIP method, which can treat compressible/incompressible problem and multi-phase problem. We can apply this method to the general equations by using CCUP. In this paper, non-staggered grid arrangement and predictor-corrector method are used to enhance later development and the solution accuracy and convergence performance. To validate the numerical algorithm proposed in this paper, the two-dimensional unsteady flow in the driven cavity is simulated. The numerical results of this subject using the present algorithm are compared with other numerical results. As a result, it is prived that the present scheme gives stable and improved solutions, and the results even coarse grid are in good agreement with other result using a fine grid arrangement.

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COMPUTATIONS ON FLOW FIELDS AROUND A 3D FLAPPING PLATE USING THE HYBRID CARTESIAN/IMMERSED BOUNDARY METHOD (HCIB 법을 이용한 변형하는 평판 주위의 3차원 유동해석)

  • Shin, Sang-Mook
    • Journal of computational fluids engineering
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    • v.12 no.1
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    • pp.1-8
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    • 2007
  • A code is developed using the hybrid Cartesian/immersed boundary method and it is applied to simulate flows around a three-dimensional deforming body. A new criterion is suggested to distribute the immersed boundary nodes based on edges crossing a body boundary. Velocities are reconstructed at the immersed boundary nodes using the interpolation along a local normal line to the boundary. Reconstruction of the pressure at the immersed boundary node is avoided using the hybrid staggered/non-staggered grid method. The developed code is validated through comparisons with other experimental and numerical results for the velocity profiles around a circular cylinder under the forced in-line oscillation and the pressure coefficient distribution on a sphere. The code is applied to simulate the flow fields around a plate whose tail is periodically flapping under a translation. The effects of the velocity and acceleration due to the deformation on the periodic shedding of pairs of tip vortices are investigated.

Discretization of Pressure-Poisson Equation for Solving Incompressible Navier-Stokes Equations Using Non-Staggered Grid (정규격자를 사용한 비압축성 Navier-Stokes 방정식의 수치해석을 위한 압력 Poisson 방정식의 이산화)

  • Kim Y. G.;Kim H. T.;Kim J. J.
    • 한국전산유체공학회:학술대회논문집
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    • 1998.11a
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    • pp.96-101
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    • 1998
  • Various discretiation methods of Laplacian operator in the Pressure-Poisson equation are investigated for the solution of incompressible Navier-Stokes equations using the non-staggered grid. Laplacian operators previously proposed by other researchers are applied to a Driven-Cavity problem. The computational results are compared with those of Ghia. The results show the characteristics of the discrete Laplacian operators.

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NUMERICAL SIMULATION ON FLUID-STRUCTURE INTERACTION OF A TWO-DIMENSIONAL ORBITING FLEXIBLE FOIL (선회하는 2차원 유연 날개의 유체-구조 상호작용 모사)

  • Shin, Sang-Mook
    • Journal of computational fluids engineering
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    • v.12 no.2
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    • pp.37-45
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    • 2007
  • The hybrid Cartesian/immersed boundary method is applied to simulate fluid-structure interaction of a two-dimensional orbiting flexible foil. The elastic deformation of the flexible foil is modelled based on the dynamic equation of a thin-plate. At each time step, the locations and velocities of the Lagrangian control points on the flexible foil are used to reconstruct the boundary conditions for the flow solver based on the hybrid staggered/non-staggered grid. To test the developed code, the flow fields around a flapping elliptical wing are calculated. The time history of the vertical force component and the evolution of the vorticity fields are compared with recent other computations and good agreement is achieved. For the orbiting flexible foil, the vorticity fields are compared with those of the case without the deformation. The combined effects of the angle of attack and the orbit on the deformation are investigated. The grid independency study is carried out for the computed time history of the deformation at the tip.

Effect of Nonuniform Vertical Grid on the Accuracy of Two-Dimensional Transport Model

  • Lee, Chung-Hui;Cheong, Hyeong-Bin;Kim, Hyun-Ju;Kang, Hyun-Gyu
    • Journal of the Korean earth science society
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    • v.39 no.4
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    • pp.317-326
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    • 2018
  • Effect of the nonuniform grid on the two-dimensional transport equation was investigated in terms of theoretical analysis and finite difference method (FDM). The nonuniform grid having a typical structure of the numerical weather forecast model was incorporated in the vertical direction, while the uniform grid was used in the zonal direction. The staggered and non-staggered grid were placed in the vertical and zonal direction, respectively. Time stepping was performed with the third-order Runge Kutta scheme. An error analysis of the spatial discretization on the nonuniform grid was carried out, which indicated that the combined effect of the nonuniform grid and advection velocity produced either numerical diffusion or numerical adverse-diffusion. An analytic function is used for the quantitative evaluation of the errors associated with the discretized transport equation. Numerical experiments with the non-uniformity of vertical grid were found to support the analysis.

A Study on the Fluid Flow and Heat Transfer Around a Staggered Tube Bundles Using a Low-Reynolds $k-\epsilon$ Turbulence Model (저레이놀즈수 $k-\epsilon$ 난류모델을 사용한 엇갈린 관군 주위에서의 유동 및 열전달에 관한 연구)

  • 김형수;최영기;유홍선
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.1
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    • pp.212-218
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    • 1995
  • Turbulent flow and heat transfer characteristics around staggered tube bundles were studied using a non-orthogonal boundary fitted coordinate system and the low Reynolds .kappa. - .epsilon. turbulence model suggested by Lam and Bremhorst. The predicted flow characteristics for two tube pitches and tube arrangement showed good agreement with the experimental data except the strongly curved region. The predicted Nusselt number was compared with measurements obtained in the staggered rough bundles and it revealed the similar trend to measurements, but the location of the maximum and minimum heat transfer differed somewhat from the measurements.

The Semi-Implicit Numerical Scheme for Transient Two-Phase Flows on Unstructured Grids (과도 다차원 2상 유동 해석을 위한 비정렬 격자계에서의 Semi-Implicit 수치 해법 개발)

  • Cho, H.K.;Park, I.K.;Yoon, H.Y.;Kim, J.;Jeong, J.J.
    • Journal of Energy Engineering
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    • v.17 no.4
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    • pp.218-226
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    • 2008
  • A component-scale two-phase analysis code has been developed for a realistic simulation of two-phase flow transients in a light water nuclear reactor component. In the code, a two-fluid three-field model is adopted and the governing equations are solved on an unstructured mesh. For the numerical solution scheme, the semi-implicit method used in the RELAP5 code was selected, which has been proved to be very stable and accurate for most of practical applications. However, some modifications were needed for its application to an unstructured non-staggered grid. This paper presents the modified semi-implicit numerical method for unstructured grid and the preliminary results of the calculations.

A Finite Volume Method for Computations of Two-Dimensional Laminar Flows (이차원 층류유동 해석을 위한 유한체적법)

  • Kim, Ki-Sup;Chung, Myung-Kyoon
    • Journal of the Society of Naval Architects of Korea
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    • v.29 no.3
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    • pp.59-70
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    • 1992
  • A Finite volume method for the computation of the two-dimensional, incompressible, steady, laminar Navier-Stokes equation is developed using a non-staggered grid system in a general curvilinear coordinate. The numerical pressure fluctuations, usually encountered when the non-staggered grid system is used, is suppressed by the momentum interpolation method. Flows around a NACA0012 foil section have been computed by the present method and the results show good agreements with other experimental and numerical ones.

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The Numerical Simulation of Flow Field and Heat Transfer around 3-D Tube Banks (3차원 튜브 뱅크 주위의 난류 유동장 및 열전달에 대한 수치 해석적 연구)

  • Park, S.K.;Kim, K.W.;Ryou, H.S.;Choi, Y.K.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.8 no.3
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    • pp.375-385
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    • 1996
  • Turbulent flow and heat transfer characteristics around staggered tube banks were studied using the 3-D Navier-Stokes equations and energy equation governing a steady incompressible flow, which were reformulated in a non-orthogonal coordinate system with cartesian velocity components and discretized by the finite volume method with a non-staggered variable arrangement. The predicted turbulent kinetic energy using RNG $k-{\varepsilon}$ model was lower than that of standard $k-{\varepsilon}$ model but showed same result for mean flow field quantities. The prediction of the skin friction coefficient using RNG $k-{\varepsilon}$ model showed better trend with experimental data than standard $k-{\varepsilon}$ model result. The inclined flow showed higher velocity and skin friction coefficient than transverse flow because of extra strain rate ($\frac{{\partial}w}{{\partial}y}$). Also, this was why the inclined flow showed higher local heat transfer coefficient than the transverse flow.

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