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openfoam文件读取

来源:博客园

对于openfoam或其他c++程序而言,文件的读取是尤为重要的

我们最开始学习C++时,会学到类的初始化,或者是变量定义为某个值,再对某个值进行遍历,,,类似如下:

点击查看代码
#include          // 包含头文件。using namespace std;        // 指定缺省的命名空间。int main(){    int a = 10;    int b = (10);    int c(10);    int e = {10};    int f{ 10 };    cout << "a=" << a << endl;    cout << "b=" << b << endl;    cout << "c=" << c << endl;    cout << "e=" << e << endl;    cout << "f=" << f << endl;}

尤其c++,初学时候内心非常感慨,怎么这么多初始化方式,我该用哪个现在回头看,其实能熟悉一个,其他看懂就行,看不懂都没关系,毕竟我们还有gdb或者typeid()帮忙,可以看看这个变量类型具体是什么说到底我们要问题导向目标导向,我们学习C++是为了类似openfoam这样的大工程服务的那学这么多初始化赋值,有必要吗如果是个大工程或者大程序是完全没必要的,因为大工程的数据都是从文件或者数据库中获得的你想想,要计算一个流体问题,如果有一万个网格,手打一万个三维位置就已经非常让人头疼了,更不要说上百个组分和压力等参数了,不现实所以又回到了问题的起点,读取文件很重要,那么如何从文件中初始化程序,如何读取文件


(资料图片)

在看of源码之前,不妨复习下C++是怎么读取文件的,进行下知识巩固

C++多使用fstream类或ifstream类

点击查看代码
#include #include   // ifstream类需要包含的头文件。#include      // getline()函数需要包含的头文件。using  namespace std;int main(){    string filename = R"(./test.txt)";    //ifstream fin(filename, ios::in);    ifstream fin;    fin.open(filename , ios::in);    // 判断打开文件是否成功。    // 失败的原因主要有:1)目录不存在;2)文件不存在;3)没有权限,Linux平台下很常见。    if (fin.is_open() == false)    {        cout << "打开文件" << filename << "失败。\n";  return 0;    }    string buffer;    while (fin >> buffer)    {        cout << buffer << endl;    }    fin.close();   // 关闭文件,fin对象失效前会自动调用close()。    cout << "操作文件完成。\n";}

OPENFOAM的文件读写,主要是用IOdictionary类

打开IOdictionary类的头文件,并不复杂

点击查看代码
class IOdictionary:    public baseIOdictionary{public:    // Constructors        //- Construct given an IOobject        IOdictionary(const IOobject&);        //- Construct given an IOobject and dictionary        IOdictionary(const IOobject&, const dictionary&);        //- Construct given an IOobject and Istream        IOdictionary(const IOobject&, Istream&);        //- Copy constructor        IOdictionary(const IOdictionary&);        //- Move constructor        IOdictionary(IOdictionary&&);    //- Destructor    virtual ~IOdictionary();    // Member Functions        //- Is object global        virtual bool global() const        {            return true;        }        //- Return complete path + object name if the file exists        //  either in the case/processor or case otherwise null        virtual fileName filePath() const        {            return globalFilePath(type());        }    // Member Operators        //- Move assignment        void operator=(IOdictionary&&);};

继承于baseIOdictionary类,借助于IOobject接口有五个构造函数,这五个中一个移动构造一个拷贝构造,其他类继承可以创建自己成员函数global()和filePath(),头文件还对移动构造创建了等号赋值运算符我们再看IOdictionary类的关键先生IOobject

IOobjectIOobject就稍显复杂了,我们先看openfoam对其的描述:

IOobject defines the attributes of an object for which implicit objectRegistry management is supported, and provides the infrastructure for performing stream I/O.An IOobject is constructed with an object name, a class name, an instance path, a reference to a objectRegistry, and parameters determining its storage status.

下面这张图是openfoam与该接口有关的类谱图打开regIOobject类,这是个抽象类,openfoam对regIOobject的描述为:

regIOobject is an abstract class derived from IOobject to handle automatic object registration with the objectRegistry.

刨根问底,那么再继续看IOobject类,openfoam对IOobject类的描述为:

IOobject defines the attributes of an object for which implicit objectRegistry management is supported, and provides the infrastructure for performing stream I/O.An IOobject is constructed with an object name, a class name, an instance path, a reference to a objectRegistry, and parameters determining its storage status.

看到这里,可能你都忍不住要吐槽一句,这么溯源什么时候是头

刨根问底刨个稀烂,知道结果明年再见

是的,openfoam征程就是这么快乐,快乐的我现在看起来略显迷茫这里不赘述了,最后查了好半天,大概是哈希表来的,方便查询读取。openfoam中/0,/constant以及/system文件夹中那种奇怪的文件格式肯定有适合自己的读取方法。

那我们看看IOobject类相关源码,IOobject类有四个枚举控制读取权限以及文件检查

点击查看代码
//- Enumeration defining the valid states of an IOobject        enum objectState        {            GOOD,            BAD        };        //- Enumeration defining the read options        enum readOption        {            MUST_READ,            MUST_READ_IF_MODIFIED,            READ_IF_PRESENT,            NO_READ        };        //- Enumeration defining the write options        enum writeOption        {            AUTO_WRITE = 0,            NO_WRITE = 1        };        //- Enumeration defining the file checking options        enum fileCheckTypes        {            timeStamp,            timeStampMaster,            inotify,            inotifyMaster        };

内共有六个构造函数,其中一个拷贝构造

点击查看代码
// Constructors        //- Construct from name, instance, registry, io options        IOobject        (            const word& name,            const fileName& instance,            const objectRegistry& registry,            readOption r=NO_READ,            writeOption w=NO_WRITE,            bool registerObject=true        );        //- Construct from name, instance, local, registry, io options        IOobject        (            const word& name,            const fileName& instance,            const fileName& local,            const objectRegistry& registry,            readOption r=NO_READ,            writeOption w=NO_WRITE,            bool registerObject=true        );        //- Construct from path, registry, io options        //  Uses fileNameComponents() to split path into components.        IOobject        (            const fileName& path,            const objectRegistry& registry,            readOption r=NO_READ,            writeOption w=NO_WRITE,            bool registerObject=true        );        //- Construct from copy resetting registry        IOobject        (            const IOobject& io,            const objectRegistry& registry        );        //- Construct from copy resetting name        IOobject        (            const IOobject& io,            const word& name        );        //- Copy constructor        IOobject(const IOobject& io) = default;

我们举个例子,基于这些构造函数可以这样写类似这样的读取端口:

点击查看代码
IOobject dicName(    "dicName",    runTime.timeName(),    //runTime.constant(),    mesh,    IOobject::MUST_READ,    IOobject::AUTO_WRITE) ;

再回到IOdictionary类,

通过查看IOdictionary类的构造函数,我们了解到可以在创建好的IOobject端口基础上构建,也可以直接构建IOobject端口

点击查看代码
IOdictionary dicName(        IOobject (            "dicName",            //runTime.constant(),            runTime.system(),            mesh,            IOobject::MUST_READ,            IOobject::AUTO_WRITE        )    ) ;

那么我们如何通过IOdictionary类读取openfoam内文件呢,以openfoam内置icoFoam为例$ ls cavity/0 constant system$ tree cavity/cavity/├── 0│ ├── U│ └── p├── constant│ ├── polyMesh│ │ ├── boundary│ │ ├── faces│ │ ├── neighbour│ │ ├── owner│ │ └── points│ └── transportProperties└── system├── blockMeshDict├── controlDict├── fvSchemes└── fvSolution$ head cavity/0/* -n15

  • cavity/0/U */--------------------------------- C++ -----------------------------------========= |\ / F ield | OpenFOAM: The Open Source CFD Toolbox\ / O peration | Website: https://openfoam.org\ / A nd | Version: 8\/ M anipulation |*---------------------------------------------------------------------------*/FoamFile{version 2.0;format ascii;class ** volVectorField;**object U;}// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

  • cavity/0/p */--------------------------------- C++ -----------------------------------========= |\ / F ield | OpenFOAM: The Open Source CFD Toolbox\ / O peration | Website: https://openfoam.org\ / A nd | Version: 8\/ M anipulation |*---------------------------------------------------------------------------*/FoamFile{version 2.0;format ascii;class ** volScalarField;**object p;}// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //从以上内容可以看到,U和v分别属于volVectorField类以及volScalarField类,那么就利用IOobject接口分别创建相关类如下所示:

点击查看代码
volVectorField U(        IOobject(            "U" ,            runTime.timeName() ,            mesh ,            IOobject::MUST_READ ,            IOobject::AUTO_WRITE        ) ,        mesh    );    volScalarField p(        IOobject(            "p" ,            runTime.timeName() ,            mesh ,            IOobject::MUST_READ ,            IOobject::AUTO_WRITE        ) ,        mesh    );

再看其他两个文件夹$ grep -rn "dicti" ../cavity/constant/transportProperties:12: class dictionary;./cavity/system/controlDict:12: class dictionary;./cavity/system/fvSolution:12: class dictionary;./cavity/system/blockMeshDict:12: class dictionary;./cavity/system/fvSchemes:12: class dictionary;./constant/transportProperties:12: class dictionary;./system/controlDict:12: class dictionary;./system/fvSolution:12: class dictionary;./system/blockMeshDict:12: class dictionary;./system/fvSchemes:12: class dictionary;都是dictionary类,那创建起来更方便了,比如说contorlDict文件

点击查看代码
IOdictionary controlDict(        IOobject (            "controlDict",            runTime.constant(),            //runTime.system(),            mesh,            IOobject::MUST_READ,            IOobject::AUTO_WRITE        )    ) ;

有了dictionary这个字典类,顾名思义,字典当然是很方便查找啊,而且本身也是在链表以及哈希列表基础上建立的,能用的函数就很丰富了,如lookup()等。

综上,openfoam创建了一个读取方便查找容易的类支持of进行数据处理,寻根溯源很麻烦,但是用起来还是很简单的。

正因为文件读取占用很大的比重,这篇文章写了三个多小时,我们也是借此机会对openfoam内部略窥一二,这样我们就知道我们的程序在写什么,知道其所能为与不能为。

最后奉上自己编写的openfoam codesnip ,节约大家时间

点击查看代码
//***********************************************////openfoam"Foam_IOobject": {"prefix": "IOobject_Foam_","body": ["IOobject ${1|U,p,T,dicName|}(",// "\t${2|\"U\",\"p\",\"T\"|}","\t\"${1}\",","\t//runTime.timeName(),","\t//runTime.constant(),","\tmesh,","\tIOobject::MUST_READ,","\tIOobject::AUTO_WRITE",") ;"],"description": "FOAM::IOobject"},"Foam::IOdictionary": {"prefix": "IOdictionary_Foam_","body": ["IOdictionary ${1:dicName}(","\tIOobject (",// "\t${2|\"U\",\"p\",\"T\"|}","\t\t\"${1}\",","\t\t//runTime.constant(),","\t\t//runTime.system(),","\t\tmesh,","\t\tIOobject::MUST_READ,","\t\tIOobject::AUTO_WRITE","\t)",") ;"],"description": "Foam::IOdictionary"},"Foam::volVectorField": {"prefix": "volVectorField_Foam_","body": ["volVectorField ${U}(","\tIOobject (","\t\t\"${U}\",","\t\trunTime.timeName(),","\t\tmesh,","\t\tIOobject::MUST_READ,","\t\tIOobject::AUTO_WRITE","\t),","\tmesh",") ;"],"description": "Foam::volVectorField"},"Foam::volScalarField": {"prefix": "volScalarField_Foam_","body": ["volScalarField ${p}(","\tIOobject (","\t\t\"${p}\",","\t\trunTime.timeName(),","\t\tmesh,","\t\tIOobject::MUST_READ,","\t\tIOobject::AUTO_WRITE","\t),","\tmesh",") ;"],"description": "Foam::volScalarField"},"Foam::scalar": {"prefix": "scalar","body": ["scalar "],"description": "Foam::scalar"},//***********************************************//

创作不易,如若喜欢,不胜感激,欢迎支持,欢迎指正

关键词: 点击查看 构造函数 刨根问底