Call via: SPRING Calculation Transient flow

In the transient flow calculation, the change in the flow state over time is taken into account. The change in state is caused by time-varying boundary conditions. Classic applications are, for example, flood waves in the main receiving watercourse or time-varying well withdrawals.

The transient flow can be calculated using the INSTAT and SITRA modules. The INSTAT module has the following features that the SITRA module lacks.

• The calculation of a horizontal model with a 3D sub-area

• Additional potential head value at the element centre point in the streamline calculation due to a triangular or quadrilateral decomposition of the individual elements

However, the explanations in the following chapters relate solely to the transient flow calculation with the SITRA module.

The calculation of the saturated thickness or the free surface is already described in the chapter "Steady state flow".

Theory of transient flow