Benchmark: Theis Problem
The Theis problem describes a transient lowering of the water table caused by a pumping well (see Fig. 4.1). In order to show the basic steps to set up simple numerical models with different dimensions in OGS, we consider a homogeneous, isotropic, confined aquifer in setups with different dimensions (2D, 3D, radial symmetric 1.5D and 2.5D, see also Table 4.1). For the different setups, we evaluate the plausibility of the processes GROUNDWATER_FLOW and LIQUID_FLOW to model confined groundwater flow in porous media under a stress condition. The governing equation for groundwater flow process in a confined aquifer is given in Eq. 4.1 with the primary variable hydraulic head. For the liquid flow process, Eq. 4.2 with pressure as its primary variable governs the flow. In Sect. 2.3, the derivation as well as physical meanings of groundwater flow equations are explained in great detail.