• Wind and Structures
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• 제34권6호
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• pp.483-497
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• 2022

Three-dimensional (3D) computational fluid dynamics (CFD) analysis of flow around a hipped-roof building representative of UK inland conditions are conducted. Unsteady simulations are performed using three variations of the k-ϵ RANS turbulence model namely, the Standard, Realizable, and RNG models, and their predictive capability is measured against current European building standards. External pressure coefficients and wind loading are found through the BS 6399-2:1997 standard (obsolete) and the current European standards (BS EN 1991-1-4:2005 and A1:20101). The current European standard provides a more conservative wind loading estimate compared to its predecessor and the k-ϵ RNG model falls within 15% of the value predicted by the current standard. Surface shear stream-traces and Q-criterion were used to analyze the flow physics for each model. The RNG model predicts immediate flow separation leading to the creation of vortical structures on the hipped-roof along with a larger separation region. It is observed that the Realizable model predicts the side vortex to be a result of both the horseshoe vortex and the flow deflected off it. These model-specific aerodynamic features present the most disparity between building standards at leeward roof locations. Finally, pedestrian comfort and safety criteria are studied where the k-ϵ Standard model predicts the most ideal pedestrian conditions and the Realizable model yields the most conservative levels.

• 한국전산유체공학회지
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• 제6권2호
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• pp.47-55
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• 2001

In recent years cluster systems using off-the-shelf processors and networks components have been increasing popular. Since actual performance of a cluster system varies significantly for different architectures, representative in-house codes from major application fields were executed to evaluate the actual performance of systems with different combination of CPU, network, and network topology. As an example of practical CFD(Computational Fluid Dynamics) simulations, the flow past an Onera-M6 wing and the flow past an infinite wing were simulated on clusters of Linux and several other hardware environments.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 학술대회
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• pp.239-243
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• 2008

Fluid flow in LPG injector is delayed momently around nozzle and leaked accidentally, then engine operation becomes unstable. When attached cutsole injector that we can prevent fuel from leaking. Attaching additional devices cause loss of power and pressure. In this study, We has analyzed the performance of the LPG injector nozzle by changing cutsole geometry numerously by using Computational Fluid Dynamics.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년 추계학술대회논문집
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• pp.239-243
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• 2008

Fluid flow in LPG injector is delayed momently around nozzle and leaked accidentally, then engine operation becomes unstable. When attached cutsole injector that we can prevent fuel from leaking. Attaching additional devices cause loss of power and pressure. In this study, We has analyzed the performance of the LPG injector nozzle by changing cutsole geometry numerously by using Computational Fluid Dynamics.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.68-74
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• 2011

Recently, thanks to the advanced computational power and numerical methods, it is made possible to analyze the flow around moving bodies using computational fluid dynamics techniques. In those simulations, moving mesh techniques should be able to represent both the body motion and boundary deformation, which are frequently encountered in fluid-structure interaction and/or six degree-of-freedom problems. In the present study, the staggered loosely coupling algorithm was used for fluid-structure interaction and the Laplacian operator based technique was used for moving mesh. For the verification of the developed computational method, the flow around a two-dimensional cylinder was simulated and analyzed.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.343-349
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• 2011

A loosely coupling method is adopted to combine a computational fluid dynamics (CFD) solver and the comprehensive structural dynamics (CSD) code, CAMRAD II, in a systematic manner to correlate the airloads, vortex trajectories, blade motions, and structural loads of the HART I rotor in descending flight condition. A three-dimensional compressible Navier-Stokes solver, KFLOW, using chimera overlapped grids has been used to simulate unsteady flow phenomena over helicopter rotor blades. The number of grids used in the CFD computation is about 24 million for the isolated rotor and about 37.6 million for the rotor-fuselage configuration while keeping the background grid spacing identical as 10% blade chord length. The prediction of blade airloads is compared with the experimental data. The current method predicts reasonably well the BVI phenomena of blade airloads. The vortices generated from the fuselage have an influence on airloads in the 1st and 4th quadrants of rotor disk. It appeared that presence of the pylon cylinder resulted in complex turbulent flow field behind the hub center.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.339-344
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• 2011

In the past much effort has been made to utilize advanced computational fluid dynamic (CFD) programs for aeroelastic simulations and analysis. However, it is limited in the field of unsteady aeroelasticity due to enormous size of computer memory and unreasonably long CPU time. Recently, AAEMS(Aerodynamics is Aeroelasticity minus Structure) was developed for linear time-invariant, coupled fluid-structure systems. In this paper, to demonstrate further the efficiency and accuracy of the new model reduction method, we successfully examine AGARD 445.6 wing modeled by FLUENT CFD, FSIPRO3D and NASTRAN FEM(Finite Element Method) programs. Using the ROM(Reduced Order Modeling) one can predict flutter boundary as a function of the dynamic pressure.

• 설비공학논문집
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• 제16권12호
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• pp.1156-1166
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• 2004

The shape of plate-fin type heat sink is numerically optimized to acquire the minimum pressure drop under the required temperature rise. In constrained nonlinear optimization problems of thermal/fluid systems, three fundamental difficulties such as high computational cost for function evaluations (i.e., pressure drop and thermal resistance), the absence of design sensitivity information, and the occurrence of numerical noise are commonly confronted. Thus, a sequential approximate optimization (SAO) algorithm has been introduced because it is very hard to obtain the optimal solutions of fluid/thermal systems by means of gradient-based optimization techniques. In this study, the progressive quadratic response surface method (PQRSM) based on the trust region algorithm, which is one of sequential approximate optimization algorithms, is used for optimization and the heat sink is optimized by combining it with the computational fluid dynamics (CFD).

• Journal of Advanced Marine Engineering and Technology
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• 제34권8호
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• pp.1074-1083
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• 2010

최근 자동차, 선박, 항공기의 운행시 외력에 의해 연료탱크 내의 유체가 출렁거리는 슬로싱 현상으로 인하여 구조물 내부가 손상되어 큰 영향을 미치고 있다. 따라서 적재연료의 슬로싱 영향을 최소화하기 위해서 전산유체역학적으로 유체의 거동을 정확히 해석하는데 무엇보다 중요하다. 본 연구에서는 ADINA-CFD를 이용하여 Kia 프론티어 Cargo용 연료탱크에 수직배플과 수평배플의 길이 및 개수에 따른 유체유량 및 압력의 특성을 파악하고, 코너 및 언덕 주행시 슬로싱 감소를 위해 해석하였다. 그 결과로 슬로싱 감소효과를 위해 배플의 최적길이는 수직배플의 경우 0.19 m, 수평배플의 경우 0.08 m로 나타났다. 그리고 자동차주행 경우에 코너주행 시는 수직배플이 수평배플보다 슬로싱 감소효과를 보이는 반면에, 언덕주행 시는 수평배플이 효과적이며 안정성을 나타내었다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1998년도 추계 학술대회논문집
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• pp.29-35
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• 1998

In this paper, the on-going effort and progress for developing an integrated software for automated CFD application is described. As an outcome of the effort devoted so far, a new system, ICFDIT, is developed and introduced in this paper. The new system can be used to solve fluid dynamics problems in a convenient graphical environment, and it includes a pre-processor, a main-processor, and a post-processor. Usage of the system and examples are demonstrated, and some issues for improvement of the system are discussed.