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Iteration output

  • What are those iteration records?
  • Let us take a closer look at e.g. time 0.49 s:


    Time = 0.49
  • Time means physical time in seconds


    Courant Number mean: 0.222158 max: 0.852134
  • Courant Number mean/max are mean/maximal CFL number for convergence condition. Roughly speaking, it can be ralated to the well known formula:


    $\displaystyle CFL = \frac{\vert U\vert \Delta t}{\Delta x}$(3.2)


  • Particularly, OpenFOAM uses the following formula:


    $\displaystyle CFL = \frac{\Delta t}{2 V} \sum_{i\in\text{Cell Faces}}\vert\phi_i\vert\,,$(3.3)


    where $ V$ is a cell volume, $ \phi_i$ is face volumteric flux and summation goes over each cell face
    smoothSolver:  Solving for Ux, Initial residual = 2.59115e-07, Final residual = 2.59115e-07, No Iterations 0
  • smoothSolver is linear system solver for U with smoother.
  • Linear system solver set-up is in file fvSolution
  • Solver decomposes velocity vector into components and solves them separately
  • Initial residual is a measure of stability of solution with respect to previous iteration.
  • Final residual is a residual when linear system solver has finished.
  • No Iterations is number of iterations of linear system solver


    DICPCG:  Solving for p, Initial residual = 8.63844e-07, Final residual = 8.63844e-07, No Iterations 0

  • DICPCG is linear system solver used for pressure (Diagonal Incomplete Cholesky Preconditioned Conjugate Gradient)
  • In PISO algorithm the pressure computation is repeated according to number of correctors nCorrectors


    time step continuity errors : sum local = 6.11228e-09, global = 1.51821e-18, cumulative = 1.09644e-17
  • time step continuity errors is continuity equation error, basically it is a sum of fluxes over all mesh faces and ideally should be zero


    ExecutionTime = 0.19 s  ClockTime = 1 s
  • ExecutionTime is the time elapsed since start of the computation.
  • ClockTime is the time spent on processor(s).