two general question:
IMod works with the finite difference method. The area is
divided into cells. In each cell there is a node where the
calculations take place. 1.) WHERE are the nodes in iMOD? In the
middle of the cell or at the interfaces of the grid lines?
2.) And how does iMOD handle the calculations when a layer boundary
passes exactly through a cell? For example, one half of the cell has
the transmissivity of 34 m/d and the other half has a transmissivity
of 10 m/d.
I would appreciate an answer.
1. iMOD models are calculated using the standard MODFLOW
concepts/sourcecode. This means that also in iMOD, the nodes are in
the middle of a cell
2. Perhaps the explanation in the manual in chapter 12.4 (KDW
Transmissivity) and especially figure 12.3 can help you on how MODFLOW
handles transmissivity. If I understand your question correctly:
a layer boundary cannot pass through a cell. There are 2 situations:
1) or the TOP/BOT is given in the Run file as the z interface between
layers or 2) no TOB/BOT is given (use KDW for transmissivity) and than
a layer/cell characteristic is binary; active or in-active. In
case your question is about the iMODFLOW run and the boundary
conditions; you need to use the same top/bot boundary definition as in
the iMODFLOW run.
Kind regards, Frans