• Title/Summary/Keyword: 비 정렬 격자

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VISCOUS FLOW ANALYSIS OF UNDERWATER PROPULSOR USING AN UNSTRUCTURED OVERSET MESH TECHNIQUE (비정렬 중첩격자기법을 이용한 수중추진기 주위의 점성유동 해석)

  • An, S.J.;Kwon, O.J.;Jung, Y.P.
    • 한국전산유체공학회:학술대회논문집
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    • 2010.05a
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    • pp.341-346
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    • 2010
  • In this paper, viscous flow calculation of pump-jet that is used as underwater propulsor was made by using RANS equation. For the validation, calculation for DTRC4119 marine propeller was made and reasonable agreements were obtained between the present results and the experiment. An unstructured overset mesh technique is used for analysis of relative motion between rotor and stator in pump-jet propulsor. Results for pump-jet propulsor were compared with computational results of another researcher.

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STUDY ON HIGH RESOLUTION SCHEMES IN INTERFACE CAPTURING METHODS WITH UNSTRUCTURED GRIDS (비정렬격자계를 사용하는 경계면포착법에서 HR도식에 관한 연구)

  • Kim, J.E.;Myong, H.K.
    • 한국전산유체공학회:학술대회논문집
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    • 2006.10a
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    • pp.51-56
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    • 2006
  • Several high resolution schemes such as OSHER, MUSCL, SMART, GAMMA, WACEB and CUBISTA are applied to two typical test cases of a translation test and a collapsing water column problem for the accurate capturing of fluid interfaces. It is accomplished by implementing the high resolution schemes in the in-house CFD code(PowerCFD) for computing 3-D flow with an unstructured cell-centered method, which is based on the finite-volume technique and fully conservative. The calculated results are found to show that SMART scheme gives the best performance with respect to accuracy and robustness.

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A THREE-DIMENSIONAL UNSTRUCTURED FINITE VOLUME METHOD FOR ANALYSIS OF DROPLET IMPINGEMENT IN ICING (비정렬 격자 기반의 결빙 액적 해석을 위한 유한체적 기법)

  • Jung, K.Y.;Jung, S.K.;Myong, R.S.
    • Journal of computational fluids engineering
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    • v.18 no.2
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    • pp.41-48
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    • 2013
  • Ice accretion on the solid surface is an importance factor in assessing the performance of aircraft and wind turbine blade. Changes in the external shape due to ice accretion can greatly deteriorate the aerodynamic performance. In this study, a three-dimensional upwind-type second-order positivity-preserving finite volume CFD scheme based on the unstructured mesh topology is developed to simulate two-phase flow in atmospheric icing condition. The code is then validated by comparing with NASA IRT experimental data on the sphere. The present results of the collection efficiency are found to be in close agreement with experimental data and show improvement near the stagnation region.

An Implicit Unstructured Finite Element Method for Diffraction of Water Waves by Two-Dimensional Floating Breakwaters (부유체 주위의 2차원 회절 문제를 위한 내율적 비정렬 격자 유한요소해법)

  • 정구창
    • Journal of Ocean Engineering and Technology
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    • v.11 no.4
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    • pp.90-101
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    • 1997
  • A hybrid element method is presented for two-dimensional diffraction problem of water waves. In this method, only a limited fluid domain close to irregular bodies is discretized into conventional finite elements, while the remaining infinite domain is treated as one element with analytical representations of high accuracy. A finite element grid is automatically generated by using Dealunay triangulation based on the Bowyer's algorithm and a linear system of equations is approximately solved with the ILU-CGS algorithm. To validate the present scheme, Computational results are compared with the existing experimental data and other numerical solutions.

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DEVELOPMENT OF CFD PROGRAM BASED ON A UNSTRUCTURED POLYHEDRAL GRID AND ITS APPLICATION TO FLOW AROUND A OSCILLATING CIRCULAR CYLINDER (비정렬 다면체 격자계 기반 유동 해석 프로그램의 개발 및 진동하는 실린더 주변 유동에의 적용)

  • Lee, Sang-Hyuk;Kang, Seong-Won;Hur, Nahm-Keon
    • 한국전산유체공학회:학술대회논문집
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    • 2011.05a
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    • pp.483-487
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    • 2011
  • In the present study, a CFD program based on a finite volume method was developed by using an unstructured polyhedral grid system for the accurate simulation with the complex geometry of computational domain. To simulate the transient flow induced by the moving solid object, the program used a fractional step method and a ALE (Algebric Lagrangian-Eulerian) method. The grid deformation for the moving of solid object were performed with a spring analogy based on the center coordinate of each computational grid. To verify the present program with these methodologies, the numerical results of the flow around the fixed and oscillating circular cylinder were compared with the previous numerical results.

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ANALYSIS OF FLOW AROUND SHIP USING UNSTRUCTURED GRID (비정렬 격자를 이용한 선체 주위의 유동 해석)

  • Jun, Jae-Hyoung;Lee, Sang-Eui;Kwon, Jae-Woong;Son, Jae-Woo
    • 한국전산유체공학회:학술대회논문집
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    • 2011.05a
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    • pp.187-193
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    • 2011
  • In this report, We compared the actual test with the result of pow calculation and Resistance/Self-propulsion of the ship using STAR-CCM+ which is the commercial Reynolds Averaged Navier-Strokes(RANs) Solver. The calculation model was the KRISO Container Ship and 205K Bulk Carrier of Sungdong shipbuilding company. For this calculation, We used Realizable K-Epsilon model for flaw analysis, VOF method for the free surface creation, Moving Reference Frame method for reducing the POW calculation time, and Sliding Mesh method for Self-Propulsion analysis. Calculation of Resistance and Self-Propulsion includes the free-surface. And all calculations in this report were based on unstructured grids.

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DES and RANS Simulations of Vortical Flows over a Slender Delta Wing on Unstructured Meshes (비정렬 격자계에서 삼각날개 주위의 와류 유동에 대한 DES 및 RANS 모사)

  • Lee, Hee-Dong;Jung, Mun-Seung;Kwon, Oh-Joon
    • 한국전산유체공학회:학술대회논문집
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    • 2008.03b
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    • pp.47-50
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    • 2008
  • The unsteady vortical flow over ONERA 70-degree delta wing was simulated using RANS and DES flow solvers on hybrid unstructured meshes. A study of time accuracy is accomplished to determine the effects of time step and number of iteration in pseudo-time stepping on numerical solutions. The grid size test is also performed to demonstrate that DES can be used to capture more accurately the unsteady vortical flow features over RANS simulation.

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DEVELOPMENT OF IMPLICIT DISCONTINUOUS GALERKIN METHOD ON UNSTRUCTURED MESHES (비정렬 격자계에서 내재적 불연속 갤러킨 기법의 개발)

  • Lee, H.D.;Kwon, O.J.
    • 한국전산유체공학회:학술대회논문집
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    • 2007.04a
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    • pp.30-40
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    • 2007
  • The implicit discontinuous Galerkin method for the two-dimensional Euler equations was developed on unstructured triangular meshes, which can achieve higher-order accuracy by wing hierachical basis functions based on Legendre polynomials. Numerical tests were conducted to estimate the convergence order of numerical solutions to the Ringleb flow and the supersonic vortex flow for which analytic solutions are available. And, the flows around a circle and a NACA0012 airfoil was also numerically simulated. Numerical results show that the implicit discontinuous Galerkin methods with higher-order representation of curved solid boundaries can be an efficient higher-order method to obtain very accurate numerical solutions on unstructured meshes.

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Ground Effect of a Rotor Blade on a Whirl Tower (훨타워 로터 블레이드의 지면효과)

  • Kang, Hee-Jung;Kim, Seung-Ho
    • Aerospace Engineering and Technology
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    • v.10 no.2
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    • pp.74-81
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    • 2011
  • A numerical simulation is performed to study the ground effect of a rotating rotor blade on a whirl tower using unstructured overset mesh. The aerodynamic change of the rotor blade by the structure around the whirl tower is also considered. The calculated results showed good agreement with the experiment for the hover performance. The ground effect of the rotor blade is investigated by comparing with the calculated results for the out of ground condition and the results of an analytic model.

Solid-Fluid Interface Treatment in Conjugate Heat Transfer Analysis using Unstructured Grid System (비정렬격자계를 사용하는 복합열전달 해석에서의 고-액 계면 처리방법)

  • Myong Hyon-Kook
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.18 no.5
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    • pp.451-457
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    • 2006
  • Conjugate heat transfer (CHT) is the simultaneous, coupled heat transfer within a fluid and an adjoining solid, and the interface treatment plays an important role in its analysis, particularly when using unstructured grid system. In the present paper a new solid-fluid interface treatment in CHT analysis is presented and applied to two typical CHT problems, i.e. natural convections in both concentric thick-walled cylinders and cavity with a centered solid body. The present interface treatment for unstructured mesh clearly demonstrates the same accuracy and robustness as that for typical structured mesh.