# esys.modellib.flow Package

## Classes

- `SteadyIncompressibleFlow`

class esys.modellib.flow.SteadyIncompressibleFlow(**kwargs)

  > *-left(etaleft(v_{i,j}+v_{j,i}

  ight) ight)_{,j}+p_{,i}=F_i*

  > sigma_{ij}=2eta D_{ij}-p,delta_{ij}

  > *D_{ij}=

  rac{1}{2}left( v_{j,i} + v_{i,j } ight)*

  > v_{k,k} = 0

  __init__(**kwargs)

    set up model

  doInitialization()

    initialize model

  doStep(dt)

    performs an iteration step of the penalty method. IterationDivergenceError is raised if pressure error cannot be reduced or max_iter is reached.

  doStepPostprocessing(dt)

    Finalises the time step.

    dt is the currently used time step size.

    This function may be overwritten.

  doStepPreprocessing(dt)

    step up pressure iteration

    if run within a time dependend problem extrapolation of pressure from previous time steps is used to get an initial guess (that needs some work!!!!!!!)

  stress()

    returns current stress

  stretching()

    returns stertching tensor

  terminateIteration()

    iteration is terminateIterationd if relative pressure change is less than rel_tol

## Functions

## Others

## Packages