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vivian

@vivian
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  • rhoCentralFoam求解器的问题
    V vivian

    谢谢您的回复!:big_mouth:
    结合tutorial中wedge15的算例,我的模拟模型为马赫数2的压缩拐角流动。入口设置了速度边界,出口为超声速出口。采用k-epsilon湍流模型,所需k,epsilon值根据经验公式给出。

    压力场设定为:

    internalField   uniform 100000;
    
    boundaryField
    {
        INLET
        
        {
            type            inletOutlet;
            inletValue      uniform 101325;
            value           uniform 101325;
        }
        
    
        OUTLET
        {
            type            waveTransmissive;
            field           p;
            phi             phi;
            rho             rho;
            psi             thermo:psi;
            gamma           1.3;
            fieldInf        100000;
            lInf            1;
            value           uniform 100000;
        }
    
        BOTTOM
        {
            type            zeroGradient;
    
        }
        TOP
        {
            type            zeroGradient;
        }
        frontAndBackPlanes
        {
            type            empty;
            
        }    
    }
    

    速度设定为:

    dimensions      [0 1 -1 0 0 0 0];
    
    internalField   uniform (600 0 0);
    
    boundaryField
    {
        INLET
        {
            type            supersonicFreestream;
            pInf            100000;
            TInf            300;
            UInf            (600 0 0);
            gamma           1.4;
            value           uniform (662 0 0);
        }
    
        OUTLET
        {
            type            inletOutlet;
            inletValue      uniform (662 0 0);
            value           uniform (662 0 0);
        }
    
        BOTTOM
        {
            type            zeroGradient;
    
        }
        TOP
        {
            type            symmetryPlane;
        }
        frontAndBackPlanes
        {
            type            empty;
            
        } 
        
    }
    

    温度场设置为:

    internalField   uniform 300;
    
    boundaryField
    {
        INLET
        {
            type            inletOutlet;
            inletValue      uniform 300;
            value           uniform 300;
        }
    
        OUTLET
        {
            type            inletOutlet;
            inletValue      uniform 300;
            value           uniform 300;
        }
    
        BOTTOM
        {
            type            zeroGradient;
    
        }
        TOP
        {
            type            symmetryPlane;
        }
        frontAndBackPlanes
        {
            type            empty;
            
        } 
    

    求解器的设置是根据相似算例给出,这个的设置有什么原则吗?我设置的如下,还请多多指点:

    solvers
    {
        "rho.*"
        {
            solver          diagonal;
        }
    
        "p.*"
        {
            solver          PBiCG;
            preconditioner  DILU;
            tolerance       1e-12;
            relTol          0;
        }
    
        "(U|e).*"
        {
            $p;
            tolerance       1e-9;
        }
    
        "(nuTilda).*"
        {
            $p;
            tolerance       1e-10;
        }
    }
    
    PIMPLE
    {
        nOuterCorrectors 1;
        nCorrectors      2;
        nNonOrthogonalCorrectors 0;
    }
    

    Q1:不知道我这样设置边界条件是否合理哪?
    Q2:求解器的选择应该如何设置呢,有什么选择原则,请问有什么资料推荐码?
    Q3:在外部参数设置找不出差错,又有发散产生时,请问如何debug呢?


  • rhoCentralFoam求解器的问题
    V vivian

    最近在看rhoCentralFoam求解器,有一些问题,请教各位:
    在使用openfoam中rhoCentralFoam求解器时,我参照其中的例子结合自身算例,给定了边界条件及初始值,在计算4000步后,出现如下错误:

    --> FOAM FATAL ERROR: 
    Maximum number of iterations exceeded
    
        From function Foam::scalar Foam::species::thermo<Thermo, Type>::T(Foam::scalar, Foam::scalar, Foam::scalar, Foam::scalar (Foam::species::thermo<Thermo, Type>::*)(Foam::scalar, Foam::scalar) const, Foam::scalar (Foam::species::thermo<Thermo, Type>::*)(Foam::scalar, Foam::scalar) const, Foam::scalar (Foam::species::thermo<Thermo, Type>::*)(Foam::scalar) const) const [with Thermo = Foam::hConstThermo<Foam::perfectGas<Foam::specie> >; Type = Foam::sensibleInternalEnergy; Foam::scalar = double; Foam::species::thermo<Thermo, Type> = Foam::species::thermo<Foam::hConstThermo<Foam::perfectGas<Foam::specie> >, Foam::sensibleInternalEnergy>]
        in file /home/liyue/OpenFOAM/OpenFOAM-3.0.1/src/thermophysicalModels/specie/lnInclude/thermoI.H at line 66.
    
    FOAM aborting
    
    #0  Foam::error::printStack(Foam::Ostream&) at ~/OpenFOAM/OpenFOAM-3.0.1/src/OSspecific/POSIX/printStack.C:218
    #1  Foam::error::abort() at ~/OpenFOAM/OpenFOAM-3.0.1/src/OpenFOAM/lnInclude/error.C:249
    #2  Foam::Ostream& Foam::operator<< <Foam::error>(Foam::Ostream&, Foam::errorManip<Foam::error>) at ~/OpenFOAM/OpenFOAM-3.0.1/src/OpenFOAM/lnInclude/errorManip.H:85 (discriminator 4)
    #3  Foam::species::thermo<Foam::hConstThermo<Foam::perfectGas<Foam::specie> >, Foam::sensibleInternalEnergy>::T(double, double, double, double (Foam::species::thermo<Foam::hConstThermo<Foam::perfectGas<Foam::specie> >, Foam::sensibleInternalEnergy>::*)(double, double) const, double (Foam::species::thermo<Foam::hConstThermo<Foam::perfectGas<Foam::specie> >, Foam::sensibleInternalEnergy>::*)(double, double) const, double (Foam::species::thermo<Foam::hConstThermo<Foam::perfectGas<Foam::specie> >, Foam::sensibleInternalEnergy>::*)(double) const) const at ~/OpenFOAM/OpenFOAM-3.0.1/src/thermophysicalModels/specie/lnInclude/thermoI.H:66
    #4  Foam::species::thermo<Foam::hConstThermo<Foam::perfectGas<Foam::specie> >, Foam::sensibleInternalEnergy>::TEs(double, double, double) const at ~/OpenFOAM/OpenFOAM-3.0.1/src/thermophysicalModels/specie/lnInclude/thermoI.H:425
    #5  Foam::sensibleInternalEnergy<Foam::species::thermo<Foam::hConstThermo<Foam::perfectGas<Foam::specie> >, Foam::sensibleInternalEnergy> >::THE(Foam::species::thermo<Foam::hConstThermo<Foam::perfectGas<Foam::specie> >, Foam::sensibleInternalEnergy> const&, double, double, double) const at ~/OpenFOAM/OpenFOAM-3.0.1/src/thermophysicalModels/specie/lnInclude/sensibleInternalEnergy.H:126
    #6  Foam::species::thermo<Foam::hConstThermo<Foam::perfectGas<Foam::specie> >, Foam::sensibleInternalEnergy>::THE(double, double, double) const at ~/OpenFOAM/OpenFOAM-3.0.1/src/thermophysicalModels/specie/lnInclude/thermoI.H:365
    #7  Foam::hePsiThermo<Foam::psiThermo, Foam::pureMixture<Foam::constTransport<Foam::species::thermo<Foam::hConstThermo<Foam::perfectGas<Foam::specie> >, Foam::sensibleInternalEnergy> > > >::calculate() at ~/OpenFOAM/OpenFOAM-3.0.1/src/thermophysicalModels/basic/psiThermo/hePsiThermo.C:46 (discriminator 2)
    #8  Foam::hePsiThermo<Foam::psiThermo, Foam::pureMixture<Foam::constTransport<Foam::species::thermo<Foam::hConstThermo<Foam::perfectGas<Foam::specie> >, Foam::sensibleInternalEnergy> > > >::correct() at ~/OpenFOAM/OpenFOAM-3.0.1/src/thermophysicalModels/basic/psiThermo/hePsiThermo.C:143
    #9  ? at ~/OpenFOAM/OpenFOAM-3.0.1/applications/solvers/compressible/rhoCentralFoam/rhoCentralFoam.C:232
    #10  __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
    #11  ? at ??:?
    Aborted (core dumped)
    

    结合前面求解e方程残差无变化,我分析,这是由于e的求解修正出现了错误,为查找错误来源,我想在rhoCentralFoam的求解器中加断点,看求解过程中的数值传递与变化。

    于是,我采用了debug模式在rhoCentralFoam.C的215行加入断点,想输出e,结果屏幕输出了大量信息,我应该如何输出才能得到想要的场信息呢?

    1. 如果我想梳理出程序运行的主线,搞清楚从场的离散点到通过离散方法,获得最终求解的代数方程矩阵,我认为最好的办法是从建立场开始,关注场中存储的离散点的信息变化。那么请问如何输出存储点压力,面通量信息的矩阵呢?

  • 关于可压缩高速流求解sonicFoam求解器
    V vivian

    谢谢东岳大神的回复,看了您推荐的,感觉有点明白了,还在挣扎中。


  • 关于可压缩高速流求解sonicFoam求解器
    V vivian

    刚刚开始接触openfoam,要做高超声速的模拟,看了求解器,认为sonicFoam比较合适,看这个求解器有很多疑问,向大神们请教。

    1. sonicFoam求解器
        while (runTime.loop())
        {
            Info<< "Time = " << runTime.timeName() << nl << endl;
    
            #include "compressibleCourantNo.H"
    
            #include "rhoEqn.H"
    
            // --- Pressure-velocity PIMPLE corrector loop
            while (pimple.loop())
            {
                #include "UEqn.H"
                #include "EEqn.H"
    
                // --- Pressure corrector loop
                while (pimple.correct())
                {
                    #include "pEqn.H"
                }
    
                if (pimple.turbCorr())
                {
                    turbulence->correct();
                }
            }
    
            rho = thermo.rho();
    
            runTime.write();
    
            Info<< "ExecutionTime = " << runTime.elapsedCpuTime() << " s"
                << "  ClockTime = " << runTime.elapsedClockTime() << " s"
                << nl << endl;
        }
    

    Q1. 基于压力基求解,我的理解是"rhoEqn.H"是基于质量守恒方程求得密度,这个方程加fvOptions是基于源项中的密度修正吗?主要来源是哪里呢?

    {
        fvScalarMatrix rhoEqn
        (
            fvm::ddt(rho)
          + fvc::div(phi)
          ==
            fvOptions(rho)
        );
    

    Q2. 求解能量方程,为什么有这一项fvc::ddt(rho, K) + fvc::div(phi, K),求解的能量方程是什么样子的那?感觉跟平时推导的能量方程有很多差距?
    能指点一下这个求解器的推导吗?不胜感激。


  • 关于 phi 和 fvVectorMatrix 的两个问题
    V vivian

    @cfd-china 您好,谢谢您的回复。是替换了的,是我给他速度赋值赋错啦。。


  • 关于simpleFoam中kEpsilon中k和epsilon的设定
    V vivian

    多谢您的回复


  • 关于simpleFoam中kEpsilon中k和epsilon的设定
    V vivian

    谢谢您的回复。我又查了一下,把特征长度L用我的进口长度乘以0.05可以运行了。之前我是看一个视频上选择乘以0.08.您说的松弛因子我一般取为0.8。请问这个的选取有什么规则吗?


  • 关于 phi 和 fvVectorMatrix 的两个问题
    V vivian

    @mengweilm425 您好 看了你的研究过程,觉得很好。我也想这样分步骤运行各个程序,以分清各个量含义。请问您是怎么做到的。我先编译了自己求解器,在文件中加入自己想输出的量,希望在输出中出现想看到的量。结果并没有看到想看的内容。请问您是如何。。


  • 关于simpleFoam中kEpsilon中k和epsilon的设定
    V vivian

    kepsilon模型中k的选择和epsilon的选择根据公式算出,
    0_1476111011982_upload-aaccde47-b559-4023-bc98-ee7f8100e9bf
    但计算结果一直显示发散,如下图
    0_1476111104742_upload-6e7b27bb-d32b-492b-97c2-b6c212a2815a
    我认为是由于k和epsilon的初始值选择不恰当造成的。不知道大家怎么选择这两个值?
    (计算背景:来流0.1m/s的圆柱绕流,雷诺数设置为2000,各边界设置如下:)
    压力设置:

    internalField   uniform 0;
    
    boundaryField
    {
        INLET
        {
            type            freestreamPressure;
           
        }
    
        OUTLET
        {
            type            freestreamPressure;
          
        }
         TOP
        {
            type            zeroGradient;
            
        }
        BOTTOM
        {
           type            zeroGradient;
        }
        CYLI
        {
            type            slip;
        }
        frontAndBack
        {
            type            empty;
        }
    }
    

    速度设置:

    internalField   uniform (0.1 0 0);
    
    boundaryField
    {
       INLET
        {        
               type         freestream;
            freestreamValue        uniform    (0.1 0 0);
        }
    
        OUTLET
        {
           type         freestream;
           freestreamValue        uniform    (0.1 0 0);
        }
         TOP
        {
           type             zeroGradient;
        }
        BOTTOM
        {
            type            zeroGradient;
        }
        CYLI
        {
            type            fixedValue;
            value           uniform (0 0 0);
        }
        frontAndBack
        {
            type            empty;
        }
    }
    

    nut

    internalField   uniform 0;
    
    boundaryField
    {
        INLET
        {
            type            freestream;
            freestreamValue uniform 0;
        }
    
        OUTLET
        {
            type            freestream;
            freestreamValue uniform 0;
        }
        
        TOP
        {
            type            zeroGradient;
            
        }
        BOTTOM
        {
           type            zeroGradient;
        }
    
        CYLI
        {
            type            kqRWallFunction;
            value           uniform 0;
        }
    
        frontAndBack
        {
            type            empty;
        }
    }
    

  • 运行中残差一直输出为0
    V vivian

    明白了。谢谢~


  • 运行中残差一直输出为0
    V vivian

    谢谢您的回复。求解可压缩不是可以选择密度基吗?我在compressible/rhoCentalFoam中修改了wedge15Ma5的例子。
    将进口速度改为改为1.5Ma下的流动。出现这种情况是什么原因呢?我应该怎么改呢?谢谢
    我入口边界压强给81134Pa,压力初始值小于入口边界,温度入口值与出口相等,为140K,速度为140K下,1.5Ma的值146M/S,初始值用0. 0_1475324060309_upload-d4bc624d-e951-4e61-b422-5be797ec835d


  • 运行中残差一直输出为0
    V vivian

    0_1475202166517_upload-5ea7482e-594b-4ead-99ec-c395c9a4c1c6
    openfoam 刚开始学习。如图,计算一个平板收缩通道的超声速流动,进口给定1.5Ma数下的速度,静压和温度,出口为zeroGradient条件,导入计算网格时,显示initial residual=0,但计算一直计算,为什么?谢谢各位大神指教!

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