开源软件OpenFOAM下投影算法实现

发布时间：2018-01-19 13:43

本文关键词： 计算流体力学 OpenFOAM 投影算法求解器　出处：《杭州电子科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：目前在工业应用中主要采用商业计算流体力学软件来完成数值模拟。商业CFD软件一般均能推出多种优化的物理模型，其应用范围十分广泛，但是商业软件自身的弱点也十分明显，如商业CFD软件需要昂贵的使用费及软件维护费等。另外，使用商业软件也就意味着我们没有自己的知识产权，这与我国发展自主创新的科技思路不符。而OpenFOAM是由英国帝国理工大学开发，采用高效C++编写的面向对象的计算流体力学开源代码程序库，由此构成一系列高效的求解器及辅助工具。OpenFOAM采用类似于我们日常习惯的方法在软件中描述偏微分方程，即它和目前大部分的商业CFD软件一样采用有限体积法对偏微分方程进行求解。另外，OpenFOAM的开放性、完全面向对象的程序设计和完善的分层框架构建，使应用者花费较少的时间便可开发自己的数值模型和求解器，是进行CFD技术研究和新数值方法开发的良好平台。投影算法在最先提出时只能用于求解流体的非稳态流动。由于该算法求解的压力泊松方程而非压力修正方程，使其在并行计算中具有很高的计算效率。经过各国研究人员的不懈努力，使投影算法的应用范围及求解精度等已经得到全面的扩大和提升。近几年，投影算法在不可压缩直接数值模拟及大涡模拟中得到大量的应用。随着高性能计算机的发展，直接数值模拟及大涡模拟将成为未来工程应用及科研发展的主要方向，因此，，在OpenFOAM平台上开发相关投影算法求解器具有很重要的意义。本文基于OpenFOAM开发平台（其本身也是一款计算流体力学软件），将已有的稳态湍流求解器simpleFoam修改为瞬态层流求解器及可应用大涡模型的瞬态湍流求解器，以及开发与投影算法相关的一系列瞬态层流求解器。文中讲解了所用的各种投影算法的求解或推导过程，并在第三章对所修改及所开发的求解器与OpenFOAM自带求解器在相应求解模型下的求解结果进行比较，以验证它们的可用性、求解精度及求解效率。第四章给出了商业CFD软件FLUENT及CFX与开源软件OpenFOAM在层流模型下的对比，目的在于验证OpenFOAM相对于商业CFD软件所具有的求解精度及求解效率。根据数值模拟的结果可知，本次对OpenFOAM自带稳态湍流求解器的修改是成功的，这在一定程度上扩大了OpenFOAM的应用范围。另外，对于在OpenFOAM平台上开发的投影算法求解器，它们不但具有良好的求解精度，还具有较好的求解效率，这使得OpenFOAM成为集SIMPLE算法、PISO算法、PIMPLE算法、PROJECTION算法的多种数值求解方法于一体的开源CFD软件。通过在OpenFOAM平台上修改算法求解器和开发投影算法求解器并进行相关数值计算，这对以后OpenFOAM平台的开发及研究具有重要的指导作用。
[Abstract]:At present, commercial computational fluid dynamics software is mainly used in industrial applications to complete numerical simulation. Commercial CFD software can generally deduce a variety of optimized physical models, and its application is very wide. But the weakness of commercial software itself is also very obvious, such as commercial CFD software needs expensive royalties and software maintenance fees. In addition, the use of commercial software also means that we do not have their own intellectual property rights. This is not in line with the idea of developing independent innovation in our country, and OpenFOAM is an object-oriented open source code library of computational fluid dynamics developed by Imperial University of Technology and written with efficient C #. This constitutes a series of efficient solvers and auxiliary tools. OpenFOAM uses a method similar to our daily habits to describe partial differential equations in software. That is to say, it uses finite volume method to solve partial differential equations just like most commercial CFD software at present. In addition, it is open to OpenFOAM. Complete object-oriented programming and complete hierarchical framework construction, so that the application can spend less time to develop their own numerical model and solver. It is a good platform for the research of CFD technology and the development of new numerical method. The projection algorithm can only be used to solve the unsteady flow of fluid in the first place, because of the pressure Poisson equation and not the pressure correction equation. Through the unremitting efforts of researchers all over the world, the range of application and accuracy of projection algorithm have been comprehensively expanded and improved. Projection algorithm has been widely used in incompressible direct numerical simulation and large eddy simulation. Direct numerical simulation and large eddy simulation will be the main directions of engineering application and scientific research in the future. Therefore, it is very important to develop the related projection algorithm on OpenFOAM platform. This paper is based on the OpenFOAM development platform (which is also a computational fluid dynamics software). The existing steady state turbulence solver (simpleFoam) is modified to transient laminar flow solver and transient turbulence solver which can be applied to large eddy model. And a series of transient laminar flow solvers related to the projection algorithm are developed. In the third chapter, the results of the modified and developed solvers are compared with those of OpenFOAM's own solver in order to verify their availability. Chapter 4th gives the comparison between commercial CFD software FLUENT and CFX and open source software OpenFOAM under laminar flow model. The purpose of this paper is to verify the accuracy and efficiency of OpenFOAM compared with commercial CFD software. According to the results of numerical simulation, the modification of OpenFOAM self-contained steady state turbulence solver is successful, which extends the application of OpenFOAM to a certain extent. For the projective algorithm solver developed on OpenFOAM platform, they not only have good accuracy, but also have good efficiency. This makes OpenFOAM a set of SIMPLE algorithm / PISO algorithm / simple algorithm. Open source CFD software with various numerical solutions for PROJECTION algorithm. By modifying the algorithm solver and developing the projection algorithm solver on the OpenFOAM platform and carrying out the correlation number. Value calculation. This will be an important guide to the development and research of OpenFOAM platform in the future.
【学位授予单位】：杭州电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TP319;TP301.6

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