Design Of The General Computational Fluid Dynamics Software Framework

Computational Fluid Dynamics (CFD) software is designed for flow field analysis,computation and prediction. Applying CFD technique to aircraft design can effectivelyimprove the quality of aircraft design, shorten the development cycles, reduce thedevelopment costs, lower the application of risk and solve lots of technical problemscan’t be carried out through the wind tunnel test. In the CFD software development,from the1990s, foreign CFD software development institutions began to applyobjective oriented technology, and did a lot of work in computer graphics, databasetechnology and standard input and output. Fruitful results have been achieved in theaspect of software stability and usability. At present, the development of domesticspecialized CFD software begins to take shape. However, these software interfacesdon’t have uniform standard, which limits the sharing and exchange of data betweendifferent CFD software and a set of standard for CFD software system has not beenformed. In response to these issues, this paper builds a general CFD softwareframework. The framework can not only directly provide integration and testingservices to related software, but also can be an open and shareable CFD softwaresecondary development platform.Main contribution of this paper consists of three parts:1)Analyse the demand offunction and interface whie different CFD programs alternation and intergration,2)propose a design scheme for general CFD software framework,3) to improvecomputational efficiency, in parallel I/O technology, propose a multi-layer physicalblock partitioning algorithm,4) through some typical examples, verify the designedframework from two aspects, then complete simulation and testing of the system.First,to offer the intergration service to the framework,this paper found severalquestions while the three programs are intergrating.To deal with these questions,weanalyse the demand of function and interface.Next, to design a software framework with well scalability and extensivecompatibility, this paper does research work from two aspects of architecture and datastructure. Through a unified top-level architecture, this paper uses a layered architecturedesign method, and the software framework is divided into multiple levels. Data istaken as transimission interface between each layer. In aspect of data structure, thispaper proposes a data exchange technology, and achieves it from various angles. Tofacilitate the secondary development this article defines a data dictionary. To avoidconfusion when define and invoke data, this article packaged the data. To easy read andprocess data, this article builds standard internal and external interfaces.Then, usually the CFD numerical calculation can not convergent until it iteratesthousands or millions of steps. Unexpected problem may interrupt computing process, so a large-scale numerical calculation software platform always has the function whichis to store computing result after some computing steps or in a period of time in order touse the known result and go on computing. But with the increase of computing scale,saving result needs a great lot of I/O operations, and this greatly decrease thecomputational efficiency. Considering the computation environment unchanged, thisthesis studies the parallel I/O algorithm from the application view. Combined with thegraph theory knowledge, this paper presents a multi-layer physical block partitioningalgorithm. In the algorithm the physical-block is treated as a unit to organize the I/Ooperator, by determining the process and the order of the physical block I/O operationsto improve I/O parallelism, and ultimately improve the computational efficiency.Finally, this thesis realize the integration of designed framework and the threeprogram. Through verify the software framework using example demonstration,expected results have been achieved. The results indicate the suggested framework hashigher reliability, parallel efficiency and well expandability.