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    400w 网格计算 水翼空化问题

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    • 小
      小考拉 最后由 编辑

      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!

      1 条回复 最后回复 回复 引用
      • 李东岳
        李东岳 管理员 最后由 编辑

        把你log文件信息贴一下,

        CFD高性能服务器 http://dyfluid.com/servers.html
        2023年,线下CFD课,预热一下 http://dyfluid.com/class.html

        1 条回复 最后回复 回复 引用
        • 小
          小考拉 最后由 编辑

          .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。。

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          • 李东岳
            李东岳 管理员 最后由 编辑

            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?

            CFD高性能服务器 http://dyfluid.com/servers.html
            2023年,线下CFD课,预热一下 http://dyfluid.com/class.html

            1 条回复 最后回复 回复 引用
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