• Title/Summary/Keyword: Deformation Interpolation

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Assessment of Interpolation Schemes in the Window Deformation PIV (조사구간 윈도우 변형을 이용한 PIV에서 보간법 평가)

  • Kim, Byoung-Jae;Sung, Hyung-Jin
    • Journal of the Korean Society of Visualization
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    • v.4 no.2
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    • pp.59-68
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    • 2006
  • We have evaluated the performances of the following six interpolation schemes used for win-dow deformation in particle image velocimetry (PIV): the linear, quadratic, B-spline, cubic, sinc, Lagrange interpolations. Artificially generated images comprised of particles of diameter in a range pixel were investigated. Three particle diameters were selected for detailed evaluation: pixel with a constant particle concentration $0.02particle/pixel^2$. Two flow patterns were considered: uniform and shear flows. The mean and random errors, and the computation times of the interpolation schemes were determined and compared.

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DEVELOPMENT OF A THREE-DIMENSIONAL MULTI-BLOCK STRUCTURED GRID DEFORMATION CODE FOR COMPLEX CONFIGURATIONS (복잡한 형상에 관한 삼차원 변형 Multi-Block 정렬격자 프로그램 개발)

  • Hoang, A.D.;Lee, Y.M.;Jung, S.K.;Nguyen, A.T.;Myong, R.S.
    • Journal of computational fluids engineering
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    • v.12 no.4
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    • pp.28-37
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    • 2007
  • In this study, a multi-block structured grid deformation code based on a hybrid of a transfinite interpolation algorithm and spring analogy was developed. The configuration was modeled by a Bezier surface. A combination of the spring analogy for block vertices and the transfinite interpolation for interior grid points helps to increase the robustness and makes it suitable for distributed computing. An elliptic smoothing operator was applied to the block faces with sub-faces in order to maintain the grid smoothness and skewness. The capability of this code was demonstrated on a range of simple and complex configurations including an airfoil and a wing-body configuration.

ASSESSMENT OF PROPERTY INTERPOLATION METHODS IN LEVEL SET METHOD (레벨셋 기법의 물성 보간 방법에 대한 고찰)

  • Park, J.K.;Oh, J.M.;Kang, K.H.
    • 한국전산유체공학회:학술대회논문집
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    • 2009.04a
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    • pp.283-289
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    • 2009
  • In level set method, material properties are made to change smoothly across an interface of two materials with different properties by introducing an interpolation or smoothing scheme. So far, the weighted arithmetic mean (WAM) method has been exclusively adopted in level set method, without complete assessment for its validity. We showed here that the weighted harmonic mean (WHM) method for rate constants of various rate processes, including viscosity, thermal conductivity, electrical conductivity, and permittivity, gives much more accurate results than the WAM method. The selection of interpolation scheme is particularly important in multi-phase electrohydrodynamic problems in which driving force for fluid flow is electrical force exerted on the phase interface. Our analysis also showed that WHM method for both electrical conductivity and permittivity gives not only more accurate, but also more physically realistic distribution of electrical force at the interface. Our arguments are confirmed by numerical simulations of drop deformation under DC electric field.

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Motion-Compensated Frame Interpolation Using a Parabolic Motion Model and Adaptive Motion Vector Selection

  • Choi, Kang-Sun;Hwang, Min-Chul
    • ETRI Journal
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    • v.33 no.2
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    • pp.295-298
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    • 2011
  • We propose a motion-compensated frame interpolation method in which an accurate backward/forward motion vector pair (MVP) is estimated based on a parabolic motion model. A reliability measure for an MVP is also proposed to select the most reliable MVP for each interpolated block. The possibility of deformation of bidirectional corresponding blocks is estimated from the selected MVP. Then, each interpolated block is produced by combining corresponding blocks with the weights based on the possibility of deformation. Experimental results show that the proposed method improves PSNR performance by up to 2.8 dB as compared to conventional methods and achieves higher visual quality without annoying blockiness artifacts.

조사구간 윈도우 변형을 이용한 PIV에서 보간법 평가

  • Kim, Byeong-Jae;Seong, Hyeong-Jin
    • 한국가시화정보학회:학술대회논문집
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    • 2006.12a
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    • pp.25-35
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    • 2006
  • We have evaluated the performances of the following six interpolation schemes used for window deformation in particle image velocimetry (PIV): the linear, quadratic, B-spline, cubic, sinc, Lagrange interpolations. Artificially generated images comprised of particles of diameter in a range $1.1{\leq}d_p\leq10.0$ pixel were investigated. Three particle diameters were selected for detailed evaluation: $d_p$=2.2, 3.3, 4.4 pixel with a constant particle concentration 0.02 $particle/pixel^2$. Two flow patterns were considered: uniform and shear flows. The mean and random errors, and the computation times of the interpolation schemes were determined and compared.

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Bending Assessment of Antisymmetric Angle-ply Composite Sandwich Plates with Various Shear Deformation Functions (전단변형함수에 따른 역대칭 앵글-플라이 복합면재를 갖는 샌드위치판의 휨거동 평가)

  • Park, Weon-Tae;Chun, Kyoung-Sik
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.11
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    • pp.5347-5356
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    • 2011
  • In this paper, we compared various shear deformation functions for modelling anti-symmetric composite sandwich plates discretized by a mixed finite element method based on the Lagrangian/Hermite interpolation functions. These shear deformation theories uses polynomial, trigonometric, hyperbolic and exponential functions through the thickness direction, allowing for zero transverse shear stresses at the top and bottom surfaces of the plate. All shear deformation functions are compared with other available analytical/3D elasticity solutions, As a result, reasonable accuracy for investigated problems are predicted. Particularly, The present results show that the use of exponential shear deformation theory provides very good solutions for composite sandwich plates.

Construction of curve-net interpolation surface considering trajectory of cross-section curves (단면곡선의 궤적을 고려한 곡선망 보간곡면 형성)

  • Yoo, Woo-Sik;Shin, Ha-Yong;Choi, Byoung-K.
    • Journal of Korean Institute of Industrial Engineers
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    • v.20 no.2
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    • pp.77-90
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    • 1994
  • Curve-net interpolation surface is one of the most popular method in engineering design. Therefore it is supported with many commercial CAD/CAM system. However, construction algorithm of curve-net interpolation surfaces is rarely opened to the public because of its copy-right. In this paper we establish a construction algorithm of curve-net interpolation surface so called sweeping surface which especially concentrates on trajectory of cross-section curve. We also show the method which can construct sweeping surfaces as NURB or Bezier mathematical models. Surfaces having the form of standard mathematical models are very useful for the application of joining, trimming, blending etc. The proposed surface interpolation scheme consists of four steps; (1) preparation of guide curves and section curves, (2) remeshing guide curves and section curves, (3) blending section curves after deformation, and (4) determination of control points for sweeping surface using gordon method. The proposed method guarantee $G^1$-continuety, and construct the surface salifying given section curves and trajectory of section curves.

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A Volume Grid Deformation Code for Computational fluid Dynamics of Moving Boundary Problems (이동경계문제의 전산유체역학을 위한 체적격자변형코드)

  • Ko, Jin-Hwan;Kim, Jee-Woong;Byun, Do-Young;Park, Soo-Hyung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.36 no.11
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    • pp.1049-1055
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    • 2008
  • Modern multidisciplinary computational fluid dynamics often incorporates moving boundaries, as would be required in the applications such as design optimization, aeroelasticity, or forced boundary motion. It is challenging to develop robust, efficient grid deformation algorithms when large displacement of the moving boundaries is required. In this paper, a volume grid deformation code is developed based on the finite macro-element and the transfinite Interpolation, and then interfaces to a structured multi-block Navier-Stokes in-house code. As demonstrated by an airfoil with pitching motion, the hysteresis loops of lift, drag and moment coefficients of the developed method are shown to be in good agreement with those of experimental data.

A refined finite element for first-order plate and shell analysis

  • Han, Sung-Cheon;Kanok-Nukulchai, Worsak;Lee, Won-Hong
    • Structural Engineering and Mechanics
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    • v.40 no.2
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    • pp.191-213
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    • 2011
  • This paper presents an improved 8-node shell element for the analysis of plates and shells. The finite element, based on a refined first-order shear deformation theory, is further improved by the combined use of assumed natural strain method. We analyze the influence of the shell element with the different patterns of sampling points for interpolating different components of strains. Using the assumed natural strain method with proper interpolation functions, the present shell element generates neither membrane nor shear locking behavior even when full integration is used in the formulation. Further, a refined first-order shear deformation theory, which results in parabolic through-thickness distribution of the transverse shear strains from the formulation based on the third-order shear deformation theory, is proposed. This formulation eliminates the need for shear correction factors in the first-order theory. Numerical examples demonstrate that the present element perform better in comparison with other shell elements.

A Static Fluid-Structure Interaction Analysis System Based on the Navier-Stokes Equations for the Prediction of Aerodynamic Characteristics of Aircraft (항공기 공력특성 예측을 위한 Navier-Stokes 방정식 기반의 정적 유체-구조 연계 해석 시스템)

  • Jung, Sun-Ki;Anh Duong, Hoang;Lee, Young-Min;Lee, Jin-Hee;Myong, Rho-Shin;Cho, Tae-Hwan
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.36 no.6
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    • pp.532-540
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    • 2008
  • Recently there are growing interests in calculating aerodynamic characteristics of aircraft configurations with structural deformation using the FSI(Fluid-Structure Interaction) system in which CFD(Computational Fluid Dynamics) and CSD(Computational Structure Dynamics) modules are coupled. In this paper the FSI system comprised of CAD, CFD, CSD, VSI(Volume Spline Interpolation) and grid deformation modules was constructed in order to investigate aerodynamic characteristics of the deformed shape. In the process VSI and grid generation modules are developed to combine CSD and CFD routines and to regenerate the aerodynamic grids for the deformed shape, respectively. For the CFD and CSD analysis, commercial programs FLUENT and NASTRAN were used. As a test model, DLR-F4 wing configuration was chosen and its aerodynamic characteristics were calculated by applying the static FSI system. It was shown that lift and drag coefficients of the wing at mach number 0.75 are reduced to 20.26% and 18.5%, respectively, owing to the structural deformation.