• 한국연소학회지
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• 제12권3호
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• pp.8-15
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• 2007

This study has numerically modelled the combustion processes of the turbulent swirling premixed lifted flames in the low-swirl burner (LSB). In these turbulent swirling premixed flames, the four tangentially-injected air jets induce the turbulent swirling flow which plays the crucial role to stabilize the turbulent lifted flame. In the present approach, the turbulence-chemistry interaction is represented by the level-set based flamelet model.. Two-dimensional and three-dimensional computations are made for the various swirl numbers and nozzle length. In terms of the centerline velocity profiles and flame liftoff heights, numerical results are compared with experimental data The three-dimensional approach yields the much better conformity with agreements with measurements without any analytic assumptions on the inlet swirl profiles, compared to the two-dimensional approach. Numerical clearly results indicate that the present level-set based flamelet approach has realistically simulated the. structure and stabilization mechanism of the turbulent swirling stoichiometric and lean-premixed lifted flames in the low-swirl burner.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.2-5
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• 2008

This study describes the numerical simulation of three-dimensional droplet formation and the following motion in a cross-junction microchannel by using the Lattice Boltzmann Method (LBM). Our aim is to develop the three-dimensional binary fluids model, consisting of two sets of distribution functions to represent the total fluid density and the density difference, which introduces the repulsive interaction consistent with a free-energy function between two fluids. We validated the LBM code with the velocity profile in a 3-dimensional rectangular channel. Then, we applied our code to the numerical simulation of a binary fluid flow in a cross-junction channel focusing on the investigation of the droplet formulation. Due to the pressure and interfacial-tension effect, one component of the fluids which is injected from one inlet is cut off into many droplets periodically by the other component which is injected from the other inlets. We considered the effect of the boundary conditions for density difference (order parameter) on the wetting of the droplet to the side walls.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.479-484
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• 2000

A Navier-stokes based finite volume method has been developed to analyze an incompressible, steady state, turbulent wall-jet flow. The standard k-e model, the RNG ${\kappa}-{\varepsilon}$ model and their nonlinear counterparts are adopted as a closure relationship. Comparison with the experimental data shows that a linear ${\kappa}-{\varepsilon}$ model performs satisfatorily for two-dimensional wall-jet flows. However, as the flow becomes three dimensional, the linear model fails to predict the spanwise jet growth accurately and the nonlinear model needs to be adopted to capture three-dimensional flow characteristics.

• KIEAE Journal
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• 제16권1호
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• pp.89-94
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• 2016

This study is part of three-dimensional(3D) heat transfer analysis program developmental process. The program is being developed without it's own built in 3D-modeller. So 3D-model must be created from another 3D-modeller such as generic CAD programs and imported to the developed program. After that, according to the 3D-geometric data form imported model, 3D-mesh created for numerical calculation. But the 3D-model created from another 3D-modeller is likely to have errors in it's geometric data such as mismatch of position between vertexes or surfaces. these errors make it difficult to create 3D-mesh for calculation. These errors are must be detected and cured in the pre-process before creating 3D-mesh. So, in this study four kinds of filters and functions are developed and tested. Firstly, 'vertex error filter' is developed for detecting and curing for position data errors between vertexes. Secondly, 'normal vector error filter' is developed for errors of surface's normal vector in 3D-model. Thirdly, 'intersection filter' is developed for extracting and creating intersection surface between adjacent objects. fourthly, 'polygon-line filter' is developed for indicating outlines of object in 3D-model. the developed filters and functions were tested on several shapes of 3D-models. and confirmed applicability. these developed filters and functions will be applied to the developed program and tested and modified continuously for less errors and more accuracy.

• 대한기계학회논문집B
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• 제20권10호
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• pp.3344-3354
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• 1996

An experimental and numerical study on the three-dimensional natural convection-radiation conjugate heat transfer in the enclosure with heat generating chip has been performed. A 3-dimensional simulation model is developed by considering heat transfer phenomena by conduction-convection and radiation. Radiative transfer was analyzed with the discrete ordinates method. Experiments are conducted in order to validate the numerical model. Comparisons with the experimental data show that good agreement is obtained when the radiation effect is considered. The effects of the thermal conductivity of the substrate and power level on heat transfer are investigated. It is shown that radiation is the dominant heat transfer mode and the conductivity of the substrate has important effects on the heat transfer in the enclosure.

• 중소기업융합학회논문지
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• 제6권4호
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• pp.93-98
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• 2016

최근 스마트 그리드와 관련된 프로젝트가 선진국을 중심으로 활발하게 연구되고 있다. 특히, 전력 문제의 장기적 안정 대책으로 분산전원이 주목받고 있다. 본 논문에서는 분산형 전원의 출력 예측을 위해서 물리모델과 통계모델을 조합하여 예측 정보 오차율을 비교분석할 수 있는 3차원 기상 수치 모델을 제안한다. 제안 모델은 분산형 전원의 예측정보를 향상시킬 수 있어 안정적인 전력계통 연계를 위한 예측시스템을 가능하다. 성능평가 결과, 제안모델은 발전량 예측 정확도가 4.6% 개선되었고, 온도보정 예측 정확도는 3.5% 향상되었다. 마지막으로 일사량 보정 정확도는 1.1% 향상되었다.

• 대한토목학회논문집
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• 제4권4호
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• pp.67-78
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• 1984

황해(黃海) 및 동지나해(東支那海)의 동수역학적(動水力學的) 3차원수치(次元數値)모델이 이 해역(海域)의 조석(潮汐), 해일(海溢), 항류순환(恒流循環) 및 조경(潮境) 등(等)의 물리적과정(物理的過程)을 연구(硏究)하기 위해 개발(開發)되었다. 본(本) 연구(硏究)에서 동지군해(東支郡海)의 3 차원(次元)모델은 1978년(年) 하절(夏節)의 5 일간(日間), 태풍(颱風)(웬디호(號))에 의(依)해 야기(惹起)된 해일(海溢)에 의한 해류분포(海流分布)를 산정(算定)하는데 적용(適用)되었다. 산정(算定)된 황해(黃海)와 동지나해(東支那海)의 지역적(地域的) 수심별해류분포(水深別海流分布)가 제시(提示)되었으며 분석검통(分析檢討)되었다. 본(本) 연구(硏究)는 역학원리(力學原理)에 입각(立脚)한 동지군해(東支郡海)의 태풍해일(颱風海溢) 예보체계(豫報體系)의 수립(樹立) 위(爲)한 첫 시도(試圖)로서 수행(遂行)된 것이다.

• 상하수도학회지
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• 제21권1호
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• pp.101-112
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• 2007

This study has used RMA2 model and RMA4 model, which are depth-averaged two-dimensional flow and water-quality prediction models, to analyze the variation of the water-quality by the gates operation in the Seonakdong River. Sensitivity analysis is performed to get the Manning coefficient and the coefficient of eddy viscosity for RMA2 model, and to get the diffusion coefficient for RMA4 model. Since the numerical simulation using RMA2 and RMA4 models did not consider tributary pollutant load except for that of Joman River, it could make a little difference from the natural phenomenon. Nevertheless, the numerical simulation shows that the discharge of $30m^3/s$, which is the continuous inflow from the Daedong-gate, can make it possible to achieve the target water-quality (BOD 4.3mg/L) of Nakbon-N watershed about 10 days later if the Daejeo-gate could remain opened in connection with the Noksan-gate operation.

• 대한토목학회논문집
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• 제14권6호
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• pp.1385-1394
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• 1994

밀도효과(密度效果)를 고려한 물의 유동(流動)에 관한 3차원(次元) 수치모형(數値模型)을 수립하여, 정상수역(靜上水域)으로의 표면온배수(表面溫排水) 확산문제(擴散問題)를 해석하였다. 수립된 수치모형(數値模型)은 수심방향에 대해 정규화(正規化)한 좌표(座標)(${\sigma}$-coordinate)에서 무차원화(無次元化)된 식들을 사용하며, 시간(時間) 적분방법(積分方法)으로는 반음해법(半陰解法)을 사용하여 계산시간의 효율성(效率性)을 도모하였다. 온배수확산(溫排水擴散) 수리실험결과(水理實驗結果)와의 비교를 통하여 모형의 신뢰성(信賴性)을 검토하였으며, 온배수(溫排水) 확산(擴散)(밀도류(密度流)) 계산시 연직확산계수(鉛直擴散係數)와 성층효과(成層效果)를 고려하기 위해 사용되는 안정함수(安定函數)의 여러 형태에 대한 계산결과를 비교하였다. 수립된 모형은 수리실험자료(水理實驗資料)와 일치하는 양호한 계산결과를 보였다. 온배수 확산 모의시 연직(鉛直) 확산계수(擴散係數)의 공간적(空間的) 분포(分布)를 고려해야함을 확인할 수 있었으며, 표면온배수 확산을 정확히 모의하기 위해서는 기존에 널리 사용되는 안정함수(安定函數)가 수정될 필요가 있었다.

• 한국해안해양공학회지
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• 제18권4호
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• pp.383-389
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• 2006

소파호안과 같은 해역구조물을 통한 월파량 산정에 수치해석기법을 적용하기 위하여 투과성 구조물의 취급 및 쇄파현상의 재현이 가능한 수치해석기법을 발판으로 하여 쇄파발생으로 인한 기포의 유입과 호안 배후의 월파로 인한 물방울의 자유낙하 및 사면유하 등을 고려할 수 있는 기법을 추가한 새로운 3차원 수치해석기법을 제안하여, 기존의 수리모형실험과 비교함으로써 그 타당성을 검증하였다. 소파호안을 대상으로 Ursell 수($=L^2H/h^3$)가 커질수록 3차원 계산에 의해 얻어지는 월파유량은 증가하였으며 실험결과와도 잘 일치하고 있는 것을 확인하였다. 또한, 월파량 산정에 2차원 및 3차원수치해석기법을 이용할 경우의 차이점에 관하여 논의하였다.