Call via: SPRING 
Calculation Transient flow
In the transient flow calculation, the change in the flow condition over the time is taken into account.
The change of state takes place through time-varying boundary conditions. Classical applications are, for example, flood waves in the main receiving water course or time-varying well withdrawals.
Currently are two calculation modules available to calculate the transient flow. These are the modules INSTAT and SITRA. The module INSTAT has two features that are currently missing in the module SITRA.
Calculation of a 2D model combined with a partially 3D model
Additional potential value in the element centre used in the streamline calculation based on a triangular or quadrilateral decomposition of the individual elements
The notes of the following chapters, however, refer only to the transient flow calculation with the module SITRA.
The computation of the thickness and the free surface is already described in chapter “Steady state flow”