groundflow_phreaticlevel_bounda method

If method is set to -method1 then the phreatic level gives the following boundary conditions.

The phreatic level is used to automatically give nodes which are located exactly on the phreatic level the boundary condition that the hydraulic pressure head is $\rho g z$. (In fact in 2D $y$ is used in stead of $z$).

Nodes above the phreatic level will be given a hydraulic pressure head of zero.

Notice that this option only works correct if the groundwater level is located exactly on nodes of the mesh.

If method is set to -method2 then the phreatic phreatic level gives the following boundary conditions.

The phreatic level is used to automatically give nodes which are located exactly on or above the phreatic level the boundary condition that the hydraulic pressure head is $\rho g z\_{phreatic}$. (In fact in 2D $y$ is used in stead of $z$).

Nodes above the phreatic level (getting also $\rho g z$) are in fact not important for the groundflow calculation results under the phreatic level.

Notice that this option also works correct if the groundwater phreatic level is not located exactly on nodes of the mesh. However, plots of the hydraulic head are more difficult to understand because nodes above the phreatic level don't get value 0 but get value $\rho g z$ (but, again, this is not important for the real groundwater results).