400w 网格计算 水翼空化问题



  • 大家好!

    最近再尝试用LES模拟水翼空化流动,用了400W的网格和interPhaseChangeFoam求解器,前期计算发现比较稳定,到0.3s之后就突然不正常了,有没有人用比较密的网格计算过水翼空化?

    我原始设置的是固定时间步2.5*e-06,我感觉可能是时间步有点大了,但更改之后效果也不是很明显

    ps:我之前用200w网格计算,效果很好,并没有出现类似的问题

    下图是监控的 云空化空穴体积随时间变化图,前面好好地,后面就有问题了。。。

    1.png

    controlDict文件代码

    // Foam Application Class
    application interPhaseChangeFoam;
    
    // Start point of run
    //startFrom       latestTime;
    startFrom       latestTime;
    
    // Calculation start time
    startTime       0;//0.399;//0;
    
    // End point of run
    stopAt          endTime;
    
    // Calculation end time
    endTime         0.5;//0.9;//5.0e-2;
    
    // Calculation time step
    deltaT          2.5e-06;//2.0e-5;//
    
    // Type of write output control
    writeControl    adjustableRunTime;
    
    // Interval with which the results are output
    writeInterval   1.0e-3;
    
    // Limits number of time directories before overwriting
    cycleWrite      0;
    
    // Write Format
    writeFormat     ascii;
    
    // Significant figures of written ASCII data
    writePrecision  6;
    
    // Write Compression
    writeCompression uncompressed;
    
    // Time directories name format
    timeFormat      general;
    
    // Decimal precision of time directory names
    timePrecision   6;
    
    // Can parameters be modified during run time?
    runTimeModifiable yes;
    
    // Automatic adjustment of time step?
    adjustTimeStep  off;
    
    // maxCo
    maxAlphaCo         0.99; // 0.2; Victor Changes to remain with courant number < 1 
    
    // maxDeltaT
    maxDeltaT     1e-2; // 1; Control the changes of delta calculation for a courant number < 1
    

    fvSchemes文件

    ddtSchemes
    {
        default         Euler;
    }
    
    gradSchemes
    {
        default         Gauss linear;
    }
    
    divSchemes
    {
        default             none;
        div(phi,alpha)  Gauss upwind;
        div(phirb,alpha) Gauss linear;
        div(phi,rho)    Gauss limitedLinear 1;
    
        div(rhoPhi,U)  Gauss upwind;
        div(phi,thermo:rho.water) Gauss upwind;
        div(phi,thermo:rho.air) Gauss upwind;
        div(rhoPhi,T)  Gauss upwind;
        div(rhoPhi,K)  Gauss upwind;
        div(phi,p)      Gauss upwind;
        div(phi,k)      Gauss upwind;
        div(rhoPhi,omega)  Gauss limitedLinear 1;
    
        div(phi,omega)   Gauss upwind;
    
        div(rhoPhi,k)   Gauss upwind;
    
        div(((rho*nuEff)*dev2(T(grad(U))))) Gauss linear;
    
    }
    
    laplacianSchemes
    {
        default         Gauss linear uncorrected;
    }
    
    interpolationSchemes
    {
        default         linear;
    }
    
    snGradSchemes
    {
        default         uncorrected;
    }
    wallDist
    {
        method meshWave;
    }
    

    一般这样 网格量很大的情况,用LES计算非定常问题,需要注意什么呢?

    求各位指点!



  • 把你log文件信息贴一下,



  • .log文件最前面的参数

    Create time
    
    Create mesh for time = 0.195
    
    
    PIMPLE: No convergence criteria found
    
    
    PIMPLE: Operating solver in PISO mode
    
    Reading field p_rgh
    
    Reading field U
    
    Reading/calculating face flux field phi
    
    AMI: Creating addressing and weights between 43430 source faces and 43430 target faces
    AMI: Patch source sum(weights) min/max/average = 0.999998, 1, 1
    AMI: Patch target sum(weights) min/max/average = 0.999994, 1, 1
    Creating phaseChangeTwoPhaseMixture
    
    Selecting phaseChange model SchnerrSauer
    Selecting incompressible transport model Newtonian
    Selecting incompressible transport model Newtonian
    Selecting turbulence model type LES
    Selecting LES turbulence model WALE
    Selecting LES delta type cubeRootVol
    LES
    {
        LESModel        WALE;
        turbulence      on;
        printCoeffs     on;
        delta           cubeRootVol;
        cubeRootVolCoeffs
        {
            deltaCoeff      1;
        }
        PrandtlCoeffs
        {
            delta           cubeRootVol;
            cubeRootVolCoeffs
            {
                deltaCoeff      1;
            }
            smoothCoeffs
            {
                delta           cubeRootVol;
                cubeRootVolCoeffs
                {
                    deltaCoeff      1;
                }
                maxDeltaRatio   1.1;
            }
            Cdelta          0.158;
        }
        vanDriestCoeffs
        {
            delta           cubeRootVol;
            cubeRootVolCoeffs
            {
                deltaCoeff      1;
            }
            smoothCoeffs
            {
                delta           cubeRootVol;
                cubeRootVolCoeffs
                {
                    deltaCoeff      1;
                }
                maxDeltaRatio   1.1;
            }
            Aplus           26;
            Cdelta          0.158;
        }
        smoothCoeffs
        {
            delta           cubeRootVol;
            cubeRootVolCoeffs
            {
                deltaCoeff      1;
            }
            maxDeltaRatio   1.1;
        }
        Ce              1.048;
        Ck              0.094;
        Cw              0.325;
    }
    
    
    Reading g
    
    Reading hRef
    Calculating field g.h
    
    No finite volume options present
    Courant Number mean: 0.00975387 max: 1.87647
    
    Starting time loop
    
    forces forceCoeffs1:
        Not including porosity effects
    forceCoeffs forceCoeffs1:
        Not including porosity effects
    fieldAverage fieldAverage1:
        Restarting averaging for fields:
            U iters = 78001 time = 0.195002
            alpha.water iters = 78001 time = 0.195002
            p iters = 78001 time = 0.195002
    
    
    
    surfaceFieldValue patchAverage:
        total faces  = 9879
        total area   = 0.003969
    

    发散之后输出的内容

    Courant Number mean: 0.00975777 max: 2.3062
    Time = 0.34437
    
    smoothSolver:  Solving for alpha.water, Initial residual = 2.45197e-06, Final residual = 4.99732e-09, No Iterations 1
    Phase-1 volume fraction = 0.997016  Min(alpha.water) = 8.9353e-06  Max(alpha.water) = 1
    MULES: Correcting alpha.water
    Liquid phase volume fraction = 0.997016  Min(alpha.water) = 8.9353e-06  Max(alpha.water) = 1
    GAMG:  Solving for p_rgh, Initial residual = 1.23064e-05, Final residual = 6.14351e-08, No Iterations 1
    GAMGPCG:  Solving for p_rgh, Initial residual = 1.53786e-06, Final residual = 9.23801e-09, No Iterations 1
    ExecutionTime = 184925 s  ClockTime = 186563 s
    
    fieldAverage fieldAverage1 write:
        Calculating averages
    
    Courant Number mean: 0.00975777 max: 2.30292
    Time = 0.344373
    
    smoothSolver:  Solving for alpha.water, Initial residual = 2.45241e-06, Final residual = 5.00226e-09, No Iterations 1
    Phase-1 volume fraction = 0.997016  Min(alpha.water) = 8.93479e-06  Max(alpha.water) = 1
    MULES: Correcting alpha.water
    Liquid phase volume fraction = 0.997016  Min(alpha.water) = 8.93479e-06  Max(alpha.water) = 1
    GAMG:  Solving for p_rgh, Initial residual = 1.21562e-05, Final residual = 6.58046e-08, No Iterations 1
    GAMGPCG:  Solving for p_rgh, Initial residual = 1.52149e-06, Final residual = 1.02397e-08, No Iterations 1
    ExecutionTime = 184928 s  ClockTime = 186566 s
    
    fieldAverage fieldAverage1 write:
        Calculating averages
    

    刚才和别人交流,感觉自己的离散格式都是一阶的,可能耗散有点大,感觉自己还要去试一试。。



  • 一阶格式更加稳定,在发散的情况下追求高阶格式会更加发散,为何不把可调节时间不长开启?


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