• Title/Summary/Keyword: curvilinear domain

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Vibration analysis of plates with curvilinear quadrilateral domains by discrete singular convolution method

  • Civalek, Omer;Ozturk, Baki
    • Structural Engineering and Mechanics
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    • v.36 no.3
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    • pp.279-299
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    • 2010
  • A methodology on application of the discrete singular convolution (DSC) technique to the free vibration analysis of thin plates with curvilinear quadrilateral platforms is developed. In the proposed approach, irregular physical domain is transformed into a rectangular domain by using geometric coordinate transformation. The DSC procedures are then applied to discretization of the transformed set of governing equations and boundary conditions. For demonstration of the accuracy and convergence of the method, some numerical examples are provided on plates with different geometry such as elliptic, trapezoidal having straight and parabolic sides, sectorial, annular sectorial, and plates with four curved edges. The results obtained by the DSC method are compared with those obtained by other numerical and analytical methods. The method is suitable for the problem considered due to its generality, simplicity, and potential for further development.

Fundamental problems for an elastic plate weakened by a curvilinear hole

  • Dowaikh, M.A.
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.8 no.1
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    • pp.81-92
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    • 2004
  • Muskhelishvili's complex variable method has been applied to derive exact and closed expressions for Gaursat's functions for the first and second fundamental problems of the infinite plate weakened by a curvilinear hole which is conformally mapped on the domain outside the unit circle by means of rational mapping function. The hole having three poles. The previous work of the authers in this domain is considered as special cases of this work.

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Numerical Simulation of 2-D Estuaries and Coast by Multi-Domain and the Interpolating Matrix Method (Multi-Domain과 행렬 보간법을 이용한 강 하구와 연안의 2차원 수치해석)

  • Chae H. S.
    • Journal of computational fluids engineering
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    • v.2 no.1
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    • pp.21-28
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    • 1997
  • This paper presents a two-dimensional horizontal implicit model to general circulation in estuaries and coastal seas. The model is developed in non-orthogonal curvilinear coordinates system, using the Interpolating Matrix Method (IMM), in combination with a technique of multi-domain. In the propose model, the Saint-Venant equations are solved by a splitting-up technique, in the successive steps; convection, diffusion and wave propagation. The ability of the proposed model to deal with full scale nature is illustrated by the interpretation of a dye-tracing experiment in the Gironde estuary.

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Second order VOF convection model in curvilinear coordinates

  • Kim, Seong-O.;Hwang, Young-dong;Kim, Young-In.;Chang, Moon-Hee
    • Proceedings of the Korean Nuclear Society Conference
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    • 1997.05a
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    • pp.392-399
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    • 1997
  • An approximation technique was developed for the simulation of free surface flows in non-orthogonal coordinates. The main idea of this approach is to approximate VOF by the second order linear equation in the transformed domain on the assumption that the continuity of free surface would be maintained. The method was justified through a set of numerical test to examine if its original shape could be maintained when the circles are convected in uniform velocity in horizontal direction in curvilinear coordinates. Finally a simple problem was solved by applying the method to CFX4.1 general purpose CFDS code.

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Flow Visualization and Numerical Calculation in a Channel Perturbed by Curvilinear Blockages (장애물을 갖는 덕트내의 유동가시화 및 수치해석에 관한 해석)

  • Moon, C.;Park, J.C.;Kim, C.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.6 no.3
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    • pp.218-226
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    • 1994
  • Laminar flow and heat transfer in a channel with blockages are obtained numerically in a Reynolds-number range of $100{\leq}Re{\leq}400$. A boundary-fitted curvilinear coordinate system is generated for irregular boundary of the physical region, and solutions of Navier-Stokes equation and energy equation are obtained by finite analytic method in the transformed computational domain. The flow separates in downstream of the blockage and the length of separated-flow region increases with Reynolds number. The heat flux is high on the top of the blockages and increase in the heat transfer occurs where the fluid reattaches the wall. Comparison between computed streamlines and experimental flow-visualization is also presented and discussed.

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Evaluation of Optimal Grid Resolution for Hydrodynamic Proper Simulation (수리동역학적 모의를 위한 적정 격자해상도 산정방법)

  • Ahn, Jung-Min;Park, In-Hyeok;Lyu, Si-Wan;Hur, Young-Teck
    • Journal of Korean Society for Geospatial Information Science
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    • v.20 no.1
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    • pp.109-116
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    • 2012
  • The effect of the grid resolution on the hydrodynamic simulation has been investigated by using CCHE2D and EFDC. Since a high resolution of the grid results in the increase of computation time, an appropriate grid resolution should be selected by considering the efficiency of simulation according to the objectives of projects. In order to understand the effect of grid resolution and determine the optimal grid resolution, several cases with different lateral grid resolutions have been simulated for the reach of Nakdong river at the confluence of Kumho river for the floods in 2006. Orthogonal curvilinear grids for the domain have been constructed from the survey products at the sections with the longitudinal interval of 20 m. Area-elevation curve and the comparison of simulated results with measured stage at the specific station have been used to check the effect of grid resolution. From the results, the existence of optimal grid resolution has been observed, which ensure both efficiency of computation and certainty of results.

Non-hydrostatic modeling of nonlinear waves in a circular channel (비정수압 모형을 이용한 원형 수로에서 비선형 파랑의 해석)

  • Choi, Doo-Yong
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.23 no.5
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    • pp.335-344
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    • 2011
  • A curvilinear non-hydrostatic free surface model is developed to investigate nonlinear wave interactions in a circular channel. The proposed model solves the unsteady Navier-Stokes equations in a three-dimensional domain with a pressure correction method, which is one of fractional step methods. A hybrid staggered-grid layout in the vertical direction is implemented, which renders relatively simple resulting pressure equation as well as free surface closure. Numerical accuracy with respect to wave nonlinearity is tested against the fifth-order Stokes solution in a two-dimensional numerical wave tank. Numerical applications center on the evolution of nonlinear waves including diffraction and reflection affected by the curvature of side wall in a circular channel comparing with linear waves. Except for a highly nonlinear bichrmatic wave, the model's results are in good agreement with superimposed analytical solution that neglects nonlinear effects. Through the numerical simulation of the highly nonlinear bichramatic wave, the model shows its capability to investigate the evolution of nonlinear wave groups in a circular channel.

A Numerical Study on Radiation of Duct Internal Noise (항공기 엔진 소음 전파에 대한 수치적 연구)

  • Cheong, Cheol-Ung;Lee, Soo-Gab
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.06a
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    • pp.98-103
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    • 2000
  • The cut-off is a unique feature associated with duct acoustics due to the presence of duct walls. Duct geometry effect on sound radiation is another issue of duct acoustics. The radiation of duct internal noise to ambient from duct open ends with various geometries is studied via numerical methods. The linearized Euler's equations in generalized curvilinear coordinates are solved by the DRP finite difference scheme. A number of accurate boundary conditions are used at boundaries for the computational domain to minimize the non-physical reflections. The far field sound pressure levels are computed by the Kirchhoff integration method. We investigate the cut off phenomana and duct geometry effects on sound radiation with numerical results.

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A Grid Adaptation Method Using the Chimera and Patched Grid Systems (중첩격자계와 접합격자계를 이용한 적응격자 기법)

  • Kim, De-Hee;Kwon, Jang-Hyuk
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.33 no.10
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    • pp.17-25
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    • 2005
  • A grid adaptation method within systems of chimera and patched grids is presented. Problem domains are divided into near-body and off-body fields. Near-body field is filled with curvilinear body-fitted grids that extend only a short distance from body surfaces and connected to other grid systems via chimera domain connectivity method. Off-body field is filled with patched uniform cartesian grids of varying levels of refinement. This method gives flexibility in grid generation and efficient adaptation capability. Several numerical experiments including 2D store separation were performed to show the performance of the proposed adaptation method.

A Study on the Characteristics of Knitwear Fashion Design: With a focus on Missoni, Sonia Rykiel, Azzedine Alaia

  • Chun, Hei Jung;Park, Jae Min
    • International Journal of Costume and Fashion
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    • v.13 no.1
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    • pp.23-34
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    • 2013
  • The purpose of this study is to better understand the development and characteristics of knitwear fashion design by examining the transformation process of the modern knits. The subjects of the study are Missoni, Sonia Rykiel, and Azzedine Alaia, designers who are world-renowned knit designers, and the expressive techniques in their designs will be evaluated. The study also intends to analyze the aesthetic value of each designer's style through their product's silhouette, colors, and knitting techniques. On the basis of the analysis, we hope to research the factors in the designing process that will allow knits, which were made for practical purposes, to be valued as a luxury fashion item, and with the results, show the potential for knits in expanding its domain in fashion to become a more luxurious, creative fashion item. The characteristic comparison of the designers is as follows: First, in the case of colors, Missoni shows its distinct identity through a balance of splashy colors as well as nature-inspired color composition and balance. And, only with color use, is also able to express perspective, form composition, and rhythm. Sonia Rykiel designs are composed of black backgrounds with strong primary colors that are contrasted with one-point or stripes to express a light, urban image. Alaia emphasizes femininity by the use of black and white colors, which show modernity, in combination with neutral skin-toned colors, such as beige and gray. So, in other words, Missoni and Sonia Rykiel mixed colors for visual interconnectivity, while Alaia expressed femininity through the use of an achromatic color. Second, in the case of knitting techniques, Missoni uses the jacquard technique to make complex patterns that show balance of colors and patterns such as zigzag, stripe, geometries, and titan check, which are geometric, abstract, and symmetric. Sonia Rykiel who uses stripes as her trademark, most often utilizes the intarsia technique, which is expressed through one-point. Alaia combines diverse techniques, such as the Skashi weaving, by using computerized knitting. Third, as for silhouettes, Missoni eliminated exaggerated details in order to emphasize the flashy colors and delicate patterns and weavings of its designs, and this resulted in simplistic and relaxed silhouettes. Sonia Rykiel took advantage of the elasticity that the knit offers to get a tight silhouette, and in turn, emphasized the female sensuality. Alaia used curvilinear cuts that emphasized the womanly curves and gained an image considered soft and feminine.