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    cavitazione.club

    @cavitazione.club

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    Latest posts made by cavitazione.club

    • 粘度场异常
      1. 速度场
        U.png
      2. 压力场
        p.png
      3. 粘度场
        nut.png

      粘度边界:进出口calculated,机翼表面nutUSpaldingWallFunction,上下边界symmetry简化问题

      计算收敛,domainminandmax监测稳定无震荡

      求解器:default interPhaseChangeFoam,ofv1912

      湍流模型:kEqn LES

      粘度场异常原因?

      posted in OpenFOAM
      C
      cavitazione.club
    • Rhie-Chow interplation

      Original RC interplation
      No time dependency, No relaxation of the velocity field:

      // Rhie-Chow interplation
      phi = (U_avg_f & mesh.Sf()) 
          - ( (DUf*( gradp_f - gradp_avg_f)) & mesh.Sf() );
      

      Time dependency, relaxation of the velocity field:

      // Rhie-Chow interplation
      phi = (U_avg_f & mesh.Sf()) 
          - ( (DUf*( gradp_f - gradp_avg_f)) & mesh.Sf() )
          + (scalar(1) - URFU)*(phi.prevIter() - (U_avg_prevIter_f & mesh.Sf()))
          + DTf*( phi_old - (U_old_f& mesh.Sf()));
      

      OpenFOAM
      No time dependency, with or without relaxation of the velocity field (check simpleFoam solver):

      surfaceScalarField phiHbyA("phiHbyA", fvc::interpolate(HbyA) & mesh.Sf());
      

      Questions: Where is the second term of the original RC? Where is the third term of the original RC if taking the relaxation of the velocity field into consideration?

      Time dependency, relaxation of the velocity field (check pisoFoam solver):

      surfaceScalarField phiHbyA
       (
           "phiHbyA",
           (fvc::interpolate(HbyA) & mesh.Sf())
         + fvc::ddtPhiCorr(rAU, U, phi)
      );
      

      Questions: ddtPhiCorr takes the function of (the third term+the fourth term of the original RC)? I guess NO. Let's recall the definition of ddtPhiCorr:

      tmp<fluxFieldType> ddtPhiCorr
      (
          new fluxFieldType
          (
              ddtIOobject,
              rDeltaT
            * this->fvcDdtPhiCoeff(U.oldTime(), phiAbs.oldTime())
            * (
                   fvc::interpolate(rA*rho.oldTime())*phiAbs.oldTime()
                 - (
                          fvc::interpolate(rA*rho.oldTime()*U.oldTime())
                        & mesh().Sf()
                    )
               )
          )
      );
      

      Look like ddtPhiCorr returns the following codes:

      fvcDdtPhiCoeff*DTf*( phi_old - (U_old_f& mesh.Sf()));
      

      Last question: How to take the effect of relaxation of the velocity field into ddtPhiCorr?
      谢谢

      posted in OpenFOAM
      C
      cavitazione.club