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복합 건축물 연결 통로에서의 기류형성에 관한 수치적 해석 연구
전병진(B.J. Jeon),장병윤(B.Y. Jang),최형권(H.G. Choi) 한국전산유체공학회 2010 한국전산유체공학회지 Vol.15 No.3
In this paper, a three-dimensional numerical study on flow pattern in winter along connecting passageway of a composite building was conducted using a commercial CFD package. The incompressible Navier-Stokes equation coupled was solved by using SIMPLE algorithm in order to find steady solutions. It was shown that a upward flow is generated inside the building in winter due to buoyancy effect and that the air inside connecting passageway flows from the shorter building to the taller one regardless of the slope of the passageway. Further, it was found that the magnitude of air velocity inside connecting passageway increases as the uphill slope to the taller building increases and decreases as the downhill slope to the taller one increases, although the variation in the magnitude of fluid velocity is not substantial. Lastly, it was shown that the maximum air velocity inside connecting passageway is less than the allowable limit for all the cases considered in this study.
냉온 도자의 열전달 특성 파악을 위한 도자와 햄/피부의 복합 열전달 해석
전병진(B.J. Jeon),최형권(H.G. Choi) 한국전산유체공학회 2018 한국전산유체공학회지 Vol.23 No.1
A conjugate heat transfer problem of Doja and Ham/Skin was simulated to investigate heat transfer characteristics of heating/cooling therapeutic modalities. Simulation results were validated by experimental data for the conjugate heat transfer of Doja and Ham and then further simulations were conducted to measure temperature variations inside skin subject to heating/cooling stimulations. We have found that the temperature of skin was higher by 1~2℃ than that of Ham under the same heating/cooling stimulations of Doja and that the temperature evolution by simulation was quite similar to that of experiment. Further, the penetration time of thermal diffusion estimated by theory was found to be close to that by simulations.
최소자승법과 Level-set 방법을 적용한 3차원 슬로싱 유동의 수치해석
전병진(Byoung Jin Jeon),최형권(Hyoung Gwon Choi) 대한기계학회 2017 大韓機械學會論文集B Vol.41 No.11
본 연구에서는 유한요소 최소자승법에 기반한 level-set 방정식의 이류방정식과 재초기화 방정식의 이산화기법을 3차원 슬로싱 문제에 적용한 코드를 개발하고, 그 성능을 평가한다. 사용된 수치기법은 정렬 격자계를 이용하여 다양한 표준 예제들에 대하여 검증이 수행되었다. 제안된 방법은 상대적으로 성긴 격자계에서 다른 기법들에 비하여 개선된 해를 줌을 확인하였다. 두 가지의 격자계에 대하여 수행한 3차원 슬로싱 해석은 상당히 성긴 격자계에서도 압력의 시간 이력이 실험결과와 잘 일치함을 보여주며, 조밀한 격자계에서는 최대압력의 크기가 크게 예측이 됨을 확인하였다. 한편, 본 연구에서 개발한 기법은 유한요소법의 특성에 의해서 비정렬 격자계를 이용하여 복잡한 형상을 가지는 용기 내의 슬로싱 문제의 해석으로 바로 확장할 수 있다. In this study, a three-dimensional least-square, level-set-based two-phase flow code was developed for the simulation of three-dimensional sloshing problems using finite element discretization. The code was validated by solving some benchmark problems. The proposed method was found to provide improved results against other existing methods, by using a coarser mesh. The results of the numerical experiments conducted during the course of this study showed that the proposed method was both robust and accurate for the simulation of three-dimensional sloshing problems. Using a substantially coarse grid, historical results of the dynamic pressure at a selected position corresponded with existing experimental data. The pressure history with a finer grid was similar to that of a coarse grid; however, a fine grid provided higher peak pressures. The present method could be extended to the analysis of a sloshing problem in a complex geometrical configuration using unstructured meshes owing to the features of FEM.
ILU 예조건화의 병렬연산을 위한 P2P1 유한요소의 Coloring 기법의 개발
전병진(Byoung Jin Jeon),최형권(Hyoung Gwon Choi) 대한기계학회 2019 大韓機械學會論文集B Vol.43 No.10
본 연구에서는 Open-MP를 이용한 병렬연산의 수행 시에, coloring 기법이 순차적인 연산이 요구되는 병렬 ILU 연산의 성능에 미치는 영향을 고찰하였다. Coloring 기법은 비압축성 Navier-Stokes 방정식의 이산화를 위하여 사용한 P2P1 유한요소를 위하여 개발하였다. 개발된 알고리즘을 이용하여 3차원 열전도 문제와 3차원 비대칭 협착관 문제를 해석하고, 다양한 격자계에 대해서 컬러링이 적용되지 않은 ILU 행렬의 단일 코어 연산시간과의 비교를 통해 Open-MP 병렬연산의 성능 향상을 측정하였다. 컬러링을 적용한 정렬 격자계의 단일 코어 연산시간은 컬러링 전보다 느려질 수 있으나, 비정렬 격자계는 메모리 접근성이 좋아지기 때문에, 단일 코어 연산시간은 컬러링 전보다 빨라질 수 있음을 확인하였다. 제안된 기법의 3차원 표준예제들에 대한 검증에서 정렬 격자계와 비정렬 격자계는 각각 약 4배와 8배의 속도향상을 주었다. We investigated the effect of the coloring method on the parallel performance of incomplete LU (ILU) computation with Open-MP. The present coloring method has been developed for P2P1 finite element method employed for solving the incompressible Navier-Stokes equations. We solved a 3-D heat conduction and an eccentric stenosis flow with the proposed method and then measured the speedup of the colored ILU computation with Open-MP over the computation without coloring. We have found that the single CPU computation with the colored structured grid may be slower than that without coloring method, but the present coloring method for unstructured grid may give a faster than that without coloring because of memory access. We have also found that the Open-MP computation of the colored ILU method for the present 3-D benchmark problems produces four times and eight times speedup with the structured and unstructured grid, respectively.
이더넷과 인피니밴드 네트워크 기반의 분산 메모리 시스템에서 병렬성능 분석
전병진(B.J. Jeon),최형권(H.G. Choi) 한국전산유체공학회 2014 한국전산유체공학회지 Vol.19 No.2
In this study, a parallel performance of CUPID-code has been investigated for both Ethernet and Infiniband network system to examine the effect of cache memory and network-speed. Bi-conjugate gradient solver of CUPID-code has been parallelised by using domain decomposition method and message passing interface (MPI). It is shown that the parallel performance of Ethernet-network system is worse than that of Infiniband-network system due to the slow network-speed and a small cache memory. It is also found that the parallel performance of each system deteriorates for a small problem due to the communication overhead, but the performance of Infiniband-network system is better than Ethernet-network system due to a much faster network-speed. For a large problem, the parallel performance depends less on network system.