How is time-stepping implemented in MODFLOWT?
Each flow stress period is subdivided into solute transport time steps. In MODFLOWT, the time step length can be limited such that the maximum local Courant number criteria is satisfied. However, since MODFLOWT can use the backward (fully implicit) or central (implicit-explicit) differencing scheme for the numerical evaluation of the time derivative, larger time steps can be used without sacrificing numerical stability or accuracy. This allows for much shorter execution times. In the example, MODFLOWT matched observed data closely while utilizing a much larger transport time step than that used in the MT3D simulations. MODFLOWT Requirements: Pentium with 8 MB RAM under Windows 95/98/2000/NT.
