• Title/Summary/Keyword: 컴팩트 차분 기법

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On the Suitability of Centered and Upwind-Biased Compact Difference Schemes for Large Eddy Simulations (III) - Dynamic Error Analysis - (LES에서 중심 및 상류 컴팩트 차분기법의 적합성에 관하여 (III) -동적 오차 해석 -)

  • Park, No-Ma;Yoo, Jung-Yul;Choi, Hae-Cheon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.7
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    • pp.995-1006
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    • 2003
  • The suitability of high-order accurate, centered and upwind-biased compact difference schemes for large eddy simulation is evaluated by a dynamic analysis. Large eddy simulation of isotropic turbulence is performed with various dissipative and non-dissipative schemes to investigate the effect of numerical dissipation on the resolved solutions. It is shown by the present dynamic analysis that upwind schemes reduce the aliasing error and increase the finite differencing error. The existence of optimal upwind scheme that minimizes total numerical error is verified. It is also shown that the finite differencing error from numerical dissipation is the leading source of numerical errors by upwind schemes. Simulations of a turbulent channel flow are conducted to show the existence of the optimal upwind scheme.

On the Suitability of Centered and Upwind-Biased Compact Difference Schemes for Large Eddy Smulation (I) - Numerical Test - (LES에서 중심 및 상류 컴팩트 차분기법의 적합성에 관하여 (I) - 수치 실험 -)

  • Park, No-Ma;Yoo, Jung-Yul;Choi, Hae-Cheon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.7
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    • pp.973-983
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    • 2003
  • The suitability of high-order accurate, centered and upwind-biased compact difference schemes is evaluated for large eddy simulation of turbulent flow. Two turbulent flows are considered: turbulent channel flow at Re = 23000 and flow over a circular cylinder at Re = 3900. The effects of numerical dissipation on the finite differencing and aliasing errors and the subgrid-scale stress are investigated. It is shown through the simulations that compact upwind schemes are not suitable for LES, whereas the fourth order-compact centered scheme is a good candidate for LES provided that proper dealiasing of nonlinear terms is performed. The classical issue on the aliasing error and the treatment of nonlinear terms is revisited with compact difference schemes.

On the Suitability of Centered and Upwind-Biased Compact Difference Schemes for Large Eddy Smulations (II) - Static Error Analysis - (LES에서 중심 및 상류 컴팩트 차분기법의 적합성에 관하여 (II) - 정적 오차 해석 -)

  • Park, No-Ma;Yoo, Jung-Yul;Choi, Hae-Cheon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.7
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    • pp.984-994
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    • 2003
  • The suitability of high-order accurate, centered and upwind-biased compact difference schemes for large eddy simulation is evaluated by a spectral, static error analysis. To investigate the effect of numerical dissipation on LES solutions, power spectra of discretization errors are evaluated for isotropic turbulence models in both continuous and discrete wavevector spaces. Contrary to the common belief, the aliasing errors from upwind-biased schemes are larger than those from comparable non-dissipative schemes. However, this result is the direct consequence of the definition of the power spectral density of the aliasing error, which poses the limitation of the static error analysis for upwind schemes.

Large Eddy Simulation of Boundary Layer Transition on the Turbine Blade (LES를 이용한 축류 터빈 경계층 천이에 대한 수치해석)

  • Jin, Byung-Ju;Park, No-Ma;Yoo, Jung-Yul
    • Proceedings of the KSME Conference
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    • 2001.06e
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    • pp.392-397
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    • 2001
  • A numerical study is performed to investigate the interaction between subsonic axial turbine blade boundary layer and periodically oncoming rotor induced wakes. An implicit scheme for solving the compressible Navier-Stokes equation is developed, which adopts a 4th-order compact difference for spatial discretiztion, a 2nd order Crank-Nicolson scheme for temporal discretization and the dynamic eddy viscosity model as the subgrid scale model. The efficiency and the accuracy of the proposed method are verified by applying to some benchmark problems such as laminar cylinder flow, laminar airfoil cascade flow and a transitional flat plate boundary layer flow. Computational results show good agreements with previous experimental and numerical results. Finally, flow through a stator cascade is simulated at $Re = 7.5{\times}10^5$ without free-stream turbulence intensity. The velocity fields and skin friction coefficients in the transitional region show similar trends with previous boundary layer natural transition.

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On Large Eddy Simulation with Centered and Upwind Compact Difference Schemes (중심 및 상류 컴팩트 차분기법을 적용한 난류유동의 LES)

  • Park Noma;Yoo Jung Yul;Choi Haecheon
    • Proceedings of the KSME Conference
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    • 2002.08a
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    • pp.807-810
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    • 2002
  • The suitability of high-order accurate, central and upwind-biased compact difference schemes is evaluated for the large-eddy simulations of flows in complex geometry. Two flow geometries are considered: channel and circular cylinder. The effects of numerical dissipation and aliasing error on the evaluation of subgrid scale stress are investigated by extending the analysis by Ghosal (1) to centered and upwind compact schemes. It is shown that the failure of upwind schemes mainly comes from the aliasing error.

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