Skip to content

Inflow/Outflow

This boundary condition allows to define an in- or outflow for infiltration/exfiltration problems, by defining the flow velocity \(v\) in m/s on the specific surface. The volumetric flow rate \(Q\) in L/T³ (usually m/s³) is computed via:

\[ Q = v \cdot A, \]

wherein \(A\) in m² is the corresponding area of the surface (calculated internally via numerical integration).

Negative values correspond to an inflow over the model boundary into the domain. Positive values prescribe an outflow (exfiltration/evaporation).

Note that the flow specified via the velocity takes places continuously on the defined surface area, independent of i.e. the pore water pressure \(p^w\). It might, however, vary over time by coupling it with an amplitude.