Steady flows

To start an unsteady flow run, an estimate of the initial conditions (flow and stage) is required at every model node. This is most often obtained by carrying out a steady state run at the proposed start time. However, steady state simulations may also be a valid modelling technique under certain conditions.

Two methods are available within Flood Modeller to compute steady flows. The Pseudo-Timestepping Method uses the Preissmann 4-point scheme, whereas the Direct Method uses a quite different and highly accurate solution technique.

Topographic data, including channel cross-sections and structure dimensions for example, are assembled into a datafile. This datafile represents the channel network system which may be very complex; it may be looped or branched and contain many interacting flow paths. The datafile will also contain the appropriate boundary conditions at the upstream and downstream extents of the model.