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CFD Analyses on Cactus PSE(Problem Solving Environment)

'The Grid' means the collaboration of computing and experimental resources in dispersed organizations by high-speed network. It has been paid much attention for an unlimited number of potential resources available and the easiness to build collaborative environments among multiple disciplines. However, the difficulty in establishing the environments and accessing and utilizing the resources has prevented application scientists from conducting Grid computing. Thus, the present study focuses on building PSE(Problem Solving Environment) which assists application researchers to easily access and utilize the Grid. The Cactus toolkit, originally developed by astrophysicists, is used as a base frame for Grid PSE. Some modules are newly developed and modified for CFD(Computational Fluid Dynamics) analysis. Simultaneously, a web portal, Grid-One portal, is built for remote monitoring/control and job migration. Cactus frame through the web portal service has been applied to various CFD problems, demonstrating that the developed PSE is valuable for large-scaled applications on the Grid.OAIID:oai:osos.snu.ac.kr:snu2005-01/104/0000004648/32SEQ:32PERF_CD:SNU2005-01EVAL_ITEM_CD:104USER_ID:0000004648ADJUST_YN:NEMP_ID:A001138DEPT_CD:446CITE_RATE:0FILENAME:Cactus_PSE의_활용을_통한_전산유체역학_문제_해석.pdfDEPT_NM:기계항공공학부EMAIL:[email protected]:

Building A Cyberinfrastructure Based Research-Education Linkage Environment

본 논문은 연구개발과 이공계 고등교육의 상호 연계를 통한 시너지 극대화를 위한 사이버 인프라스트럭처에 기반한 차세대 연구ㆍ교육 융합환경의 구축방안을 제시하고자 수행되었다. 국가 R&D 사업을 통하여 생성 및 축적된 연구결과를 이공계 대학 및 대학원의 교육 현장에 직접 연계시킬 수 있는 방안을 마련하고자 하였다. 먼저 사이버인프라 기반의 연구개발 패러다임의 변화를 검토하였다. 이어서 연구성과를 교육에 활용하여 연구과 교육의 융합을 도모한 모형과 사례들을 분석하였다. 이러한 선행연구를 바탕으로 해서 우리나라 실정에 적합한 연구ㆍ교육 융합환경 시스템을 제안하였고, e-AIRS의 사례를 들어서 구체적으로 설명하였다. 마지막으로 이러한 사업을 추진하기 위한 정책적 과제들을 논의하였다.This study purposes to suggest a next generation research and education environment which is possible by the linkage of two sectors based on cyberinfrastructure. It is to design a new research-education linkage system which can apply the results of R&D to the higher education in natural science and engineering areas. Literatures were reviewed on new paradigms of R&D triggered by the advent of cyberinfrastrcuture. A couple of overseas and domestic cases of such paradigm were introduced. With the backgrounds of case studies and theoretical models, a new research-education linkage environment system was suggested. Specially e-AIRS system was introduced as an example of new model in Korea. In addition, some policy issues were discussed as related to the successful promotion of such programs.OAIID:oai:osos.snu.ac.kr:snu2010-01/102/0000004648/4SEQ:4PERF_CD:SNU2010-01EVAL_ITEM_CD:102USER_ID:0000004648ADJUST_YN:NEMP_ID:A001138DEPT_CD:446CITE_RATE:0FILENAME:사이버인프라_기반의_연구ㆍ교육_융합환경의_구축방안.pdfDEPT_NM:기계항공공학부EMAIL:[email protected]_YN:NCONFIRM:

작업 실행관리 방법, 작업 실행 관리 장치 및 작업 실행을 관리하는 프로그램을 저장하는 저장매체

원격의 사용자가 직접 슈퍼컴퓨터에 접속하지 않아도 컴퓨팅 작업을 예약/제출할 수 있고, 시스템 접속이 불안정/불가능한 경우에도 컴퓨팅 작업 결과를 용이하게 확인할 수 있는 작업실행 관리장

A Study of Parallel Implementations of the Chimera Method

The development of a parallelized aerodynamic simulation process involving moving bodies is presented. The implementation of this process is demonstrated using a fully systemized Chimera methodology for steady and unsteady problems. This methodology consist of a Chimera hole-cutting, a new cut-paste algorithm for optimal mesh. interface generation and a two-step search method for donor cell identification. It is fully automated and requires minimal user input. All procedures of the Chimera technique are parallelized on the Cray T3E using the MPI library. Two and three-dimensional examples are chosen to demonstate the effectiveness and parallel performance of this procedure

Study of Spatial and Temporal Accuracy Estimation Related with Mesh Interafce Region on Overlapped Grids

The spatial error due to the non-conservative interpolation become first-order when second-order conservative schemes are used, discontinuities are located away from the overlapped regions, and if the length of the overlapped region is not proportional to the grid spacing. Therefore, the solution accuracy is ensured if two domains overlap each other with a fixed grid point and the interpolation is occurred in smooth flow regions. To validate the spatial and temporal accuracy due to the non-conservative interpolation, inviscid and viscous problems are tested

A Study on the Realization of Virtual Design & Development Grid System

funder : 국무조정실3.연구의 내용 및 범위 본 연구에서는 VDD Grid 시스템을 구축하기 위한 핵심기반 기술들을 확보하기 위해서 서울대학교 항공우주 구조연구실의 자원을 활용한 DCG(Departmental Computing Grid) 시스템을 구축하였으며, 그리드 컴퓨팅을 위한 다양한 수치실험을 수행하였다. DCG 시스템은 크게 3개의 클러스터 시스템과 분산 컴퓨팅 환경의 PC Farm으로 크게 구성되어 있으며, 리눅스 시스템을 기본으로 하였다. 그리드 컴퓨팅을 위해서 MPICH, PACX-MPI 등의 병렬처리용 미들웨어들과 Globus (Ver. 1.1.4)와 Condor (Ver. 6.3.1) 등과 같은 시스템 관리용 미들웨어들이 설치되어 테스트되었다. 본 연구팀이 개발하여 보유하고 있던 초대형 구조해석을 위한 병렬 다중 프런트 해법을 그리드 환경에서 최적화하기 위한 연구가 수행되었다. 먼저, 그리드 환경에서 최적화된 통신패턴을 개발하기 위한 연구가 수행되었으며 그리드 시스템을 구성하는 각 구성요소들의 성능차이를 고려한 2단계 영역분할기법을 새롭게 제시하여 연구에 활용하였다. 그리고 그리드 환경에서 초대형 구조해석을 수행하기 위해 gmsh를 이용한 효율적인 유한요소 메쉬 모델링 기법을 확보하였다. DCG 시스템과 본 연구를 통해 확보된 그리드 컴퓨팅 기술을 본 연구팀이 개발하고 있는 새로운 비파괴기법인 TSA(Tapping Sound Analayis)의 개발에 활용하여 보았다. TSA 기법은 구조물의 성문(Sound Print) 데이터의 확보를 통해 구조물의 손상 정도를 파악하는 기법인데, 이러한 성문 데이터의 확보에 많은 양의 계산이 요구되게 된다. 본 연구에서는 DCG 시스템과 분산 그리드 컴퓨팅 기술을 적용하여 TSA를 위한 구조물의 성문데이터 획득을 효율적으로 수행할 수 있었다.3.Contents and Scope In this year, DCG(Departmental Computing Grid) system was constructed to obtain the core technology about VDD Grid system. DCG system was utilized to run various numerical experiments. Three cluster systems and one PC-farm system comprise. Linux operating system was installed to each PC and MPICH, PACX-MPI were installed for parallel computing tests. Globus(Ver. 1.1.4) was installed for constructing GRID system and Condor(Ver. 6.3.1) was also installed for job-scheduling and submitting. The developed parallel multifrontal solver was modified to increase the performance in Grid computing environment. A new two-phase mesh-partitioning scheme was developed to consider the difference in performance. Also, the optimized communication pattern was investigated to minimize the communication cost in Grid environment. The finite element modeling methodology by utilizing gmsh software was studied for large-scale structural analysis. Finally, the distributed computing technology was applied to run huge computations required in TSA(Tapping Sound Anlaysis). TSA is a new NDE (Non-Destructive Evaluation) method, which determines the existence of subsurface defects by comparing the tapping sound of test structure with the tapping sound of original healthy structure. As a reference data, the tapping sound of original healthy structure is named sound print of the structure and is obtained by using high precision computation. Because many tapping points are required to obtain the exact sound print data, many times of tapping sound simulation are required. The simulation of tapping sound requires complicated numerical procedures. Therefore, TSA may not be a feasible methodology without inexpensive parallel processing technology. In this work, DCG(Departmental Computing GRID) system was utilized to run tapping sound simulations

A Simplifed Calculation Model for the Sliding Contact Boundaries in a Hydro-Static Piston Mechanism

The objective of this study was to discuss simplified calculation models for the piston/cylinder sliding mechanism in which boundary contact partly occurs invariably. An efficient prediction of the boundary leakage and friction is often needed, such as in a swash-plate axial piston machine whose lubrication test is hard to perform due to the mechanism complexity. In order to model this physically uncertain lubrication regime, two calculation models were compared to compute the lubrication behaviors: “rigid boundary model”, whose theoretical concept was previously reported in the literature, and “elastic boundary model”, newly proposed in this study. Developed numerical algorithms commonly facilitated the simultaneous calculation of body motion and fluid film pressure to observe piston motion, reaction forces, and power loss. The results showed that simulations using the elastic boundary model should be more helpful for the prediction in the earlier development stage than the previous model since the methodology provides much less simulation time than full-order calculation, higher accuracy than the rigid model, and useful engineering parameters such as surface stress. The proposed calculation model can be extended to various asymmetrically loaded reciprocating piston mechanisms for efficiently predicting the lubrication behavior