怎样限制流场中最大速度



  • 各位前辈好!

    我在compressibleInterFoam中引入了空化源项,现在调用自己写的非线性SGS模型计算的时候,流场初始速度10m/s,计算一段时间后,maxU会突然增大,导致流场发散掉,下面是速度暴增的过程

    MULES: Solving for alpha.water
    Liquid phase volume fraction = 0.997517  Min(alpha.water) = 0.000412402  Max(alpha.water) = 1
      Min(alpha.vapor) = -8.20677e-13  Max(alpha.vapor) = 0.999588
    diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
    smoothSolver:  Solving for T, Initial residual = 4.32259e-05, Final residual = 2.38488e-09, No Iterations 2
    min(T) 290.144
    GAMG:  Solving for p_rgh, Initial residual = 4.54434e-06, Final residual = 7.05483e-10, No Iterations 3
    max(U) 13.9186
    min(p_rgh) 1843.8
    GAMGPCG:  Solving for p_rgh, Initial residual = 3.62757e-07, Final residual = 4.88638e-10, No Iterations 1
    max(U) 13.9184
    min(p_rgh) 1843.67
    ExecutionTime = 275.32 s
    
    
     Integral of alpha.water = 0.00190802  [0 3 0 0 0 0 0]
    fieldAverage fieldAverage1 output:
        Calculating averages
    
    Courant Number mean: 0.00487524 max: 0.135574
    Time = 0.011952
    
    MULES: Solving for alpha.water
    Liquid phase volume fraction = 0.997517  Min(alpha.water) = 0.000413145  Max(alpha.water) = 1
      Min(alpha.vapor) = -4.79172e-13  Max(alpha.vapor) = 0.999587
    diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
    smoothSolver:  Solving for T, Initial residual = 4.324e-05, Final residual = 2.42709e-09, No Iterations 2
    min(T) 290.146
    GAMG:  Solving for p_rgh, Initial residual = 5.42286e-06, Final residual = 7.32723e-10, No Iterations 3
    max(U) 26.57
    min(p_rgh) 1813.11
    GAMGPCG:  Solving for p_rgh, Initial residual = 3.66982e-07, Final residual = 5.21535e-10, No Iterations 1
    max(U) 25.4251
    min(p_rgh) 1817.97
    ExecutionTime = 275.6 s
    
    
    fieldAverage fieldAverage1 output:
        Calculating averages
    
    Courant Number mean: 0.00487537 max: 0.135663
    Time = 0.011953
    
    MULES: Solving for alpha.water
    Liquid phase volume fraction = 0.997517  Min(alpha.water) = 0.000412369  Max(alpha.water) = 1
      Min(alpha.vapor) = -8.14016e-13  Max(alpha.vapor) = 0.999588
    diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
    smoothSolver:  Solving for T, Initial residual = 4.32537e-05, Final residual = 2.41625e-09, No Iterations 2
    min(T) 290.148
    GAMG:  Solving for p_rgh, Initial residual = 5.31025e-06, Final residual = 6.64697e-10, No Iterations 3
    max(U) 20.2828
    min(p_rgh) 1797.39
    GAMGPCG:  Solving for p_rgh, Initial residual = 3.95326e-07, Final residual = 5.53382e-10, No Iterations 1
    max(U) 20.6401
    min(p_rgh) 1803.66
    ExecutionTime = 275.88 s
    
    
    fieldAverage fieldAverage1 output:
        Calculating averages
    
    Courant Number mean: 0.00487547 max: 0.135752
    Time = 0.011954
    
    MULES: Solving for alpha.water
    Liquid phase volume fraction = 0.997516  Min(alpha.water) = 0.000412357  Max(alpha.water) = 1
      Min(alpha.vapor) = -2.22555e-12  Max(alpha.vapor) = 0.999588
    diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
    smoothSolver:  Solving for T, Initial residual = 4.32478e-05, Final residual = 2.41079e-09, No Iterations 2
    min(T) 290.15
    GAMG:  Solving for p_rgh, Initial residual = 4.91279e-06, Final residual = 6.3296e-10, No Iterations 3
    max(U) 30.2344
    min(p_rgh) 1778.9
    GAMGPCG:  Solving for p_rgh, Initial residual = 4.09173e-07, Final residual = 3.01626e-10, No Iterations 1
    max(U) 29.9168
    min(p_rgh) 1779.32
    ExecutionTime = 276.17 s
    
    
    fieldAverage fieldAverage1 output:
        Calculating averages
    
    Courant Number mean: 0.00487556 max: 0.135842
    Time = 0.011955
    
    MULES: Solving for alpha.water
    Liquid phase volume fraction = 0.997516  Min(alpha.water) = 0.000412479  Max(alpha.water) = 1
      Min(alpha.vapor) = -4.44089e-16  Max(alpha.vapor) = 0.999588
    diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
    smoothSolver:  Solving for T, Initial residual = 4.32198e-05, Final residual = 2.70013e-09, No Iterations 2
    min(T) 290.153
    GAMG:  Solving for p_rgh, Initial residual = 1.71158e-05, Final residual = 7.83321e-10, No Iterations 4
    max(U) 140.097
    min(p_rgh) 1138.55
    GAMGPCG:  Solving for p_rgh, Initial residual = 1.088e-06, Final residual = 4.13587e-10, No Iterations 2
    max(U) 147.712
    min(p_rgh) 1226.71
    ExecutionTime = 276.46 s
    

    我仔细检查发现很可能是由于求解U方程时,某个网格上面速度突然变得很大,最终导致流场发散,目前想在U方程中 或者 P方程中限制最大速度不超过某一个值,由于U是矢量,我现在不太清楚怎么限制流场中的U不超过某一个值呢?是分别限制U某一方向的速度 还是 直接限制max(mag(U).value)呢?

    麻烦哪位前辈能够指点一下呢?谢谢



  • @小考拉 maxU会突然增大只是发散的迹象,不是发散的原因,所以这种问题很难debug :135:


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