Irregular Grid

In general the flow simulation may use varying layer thickness for the vertical discretisation of the saturated zone domain. In this case, the code checks each layer to see whether its thickness is identical with the thickness of the layer above and the layer below in each of the grid cells. If this is the case this layer is handled as described for “regular grid” above (3D). If this is not the case a different approach is followed where a 2D regular grid solution based on the QUICKEST scheme is used for the horizontal transport and the verti­cal transport is taken into account as an explicit sink/source term.