- **OpenFOAM Running, Solving & CFD**
(*http://www.cfd-online.com/Forums/openfoam-solving/*)

- - **initial residual and final residual**
(*http://www.cfd-online.com/Forums/openfoam-solving/117484-initial-residual-final-residual.html*)

initial residual and final residualHi FOAMERs,
what is the definition of the initial residual and final residual, which can be used to decide convergence ? |

The initial residual is evaluated based on the current values of the field before solving an equation for a particular field . The final residual is evaluated after the solution of the equation is performed.
The intial residual is more important to decide whether a computation converges, or not. |

Hi Anne,
can you give some rule of thumbs for values, which should be achieved for the initial/final residual and how many iterations should be used for pEqn per cycle e.g. for a transient simulation with a standard PCG solver. Best Timo |

Initial residual: e^-4 or e^-5 is a good result. Final residual has to be smaller (e^-8).
I cannot answer your 2nd question. |

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