MAxSym is a MATLAB tool for the simulation of two-dimensional, non-uniform, axi-symmetric groundwater flow in saturated, porous media. MAxSym solves the governing partial differential equation using a finite-difference approach (Louwyck et al., in press). The model is axi-symmetric, which means it is used to simulate flow towards or away from an extraction well. The extraction or injection may be instantaneous, constant, or time-varying to allow simulation of slug tests and all kinds of pumping and injection tests. MAxSym can deal with wells of both small and large diameter and the well casing can be taken into account. The model is two-dimensional because it considers both radial and vertical components of the flow. By allowing hydraulic parameters to vary in the vertical direction, it is possible, for instance, to simulate flow in multi-layer systems. Non-uniform flow may be simulated by varying hydraulic parameters in the radial direction, which is useful, for instance, to consider the effect of a finite-thickness skin. The aquifer system under consideration may be confined or unconfined. If the system is unconfined, MAxSym simulates saturated flow and takes into account the time-varying saturated thickness of the top layer. Flow in the unsaturated zone on top of the system is ignored, but it is possible to define areal infiltration in the top layer. Steady state as well as transient flow conditions may be considered, the former being useful to simulate permanent groundwater extractions, the latter being necessary for the simulation of aquifer tests.
Reference: Louwyck, A., Vandenbohede, A., Bakker, M., Lebbe, L., in press. Simulation of axi-symmetric flow towards wells: A finite-difference approach. Computers & Geosciences. doi:10.1016/j.cageo.2011.09.004.