04-11-16 New version Minteq

Major revisions in the coupling of CoupModel and VMINTEQ have been undertaken during 2004. The updated code is now included in the latest version of CoupModel (2.33). A complete description will follow as soon as possible in the CoupModel Manual.

 

Examples of the improvements compared to version 2.29 (2003-11-18) are listed below:

 

Independent distribution of initial VMinteq problems and CoupModel layers - in other words, the number of initial chemical problems do not have to match the discretization of the soil profile in the hydrological model. The initial VMinteq problems (minteq_input.vda) are distributed on the physical soil layers according to their vertical extent given as parameter values.

 

Several options for the definition of initial concentrations.

 

Possibility to input precipitation chemistry via a VMinteq input file.

 

A correction of the masstransport calculation to allow for both upward and downward water flows between layers. Previously, the model code assumed only downward water flow, which introduced an error for negative (i.e upwards) water flows.

 

 Improved handling of error messages from VMinteq (no more exceptions). The interface recognises when VMinteq fails to converge and identifies the problematic layer when reading the VMinteq result file (vmint.out). An very simple algorithm to achive convergence is implemented, which is based on changing the initial pH guess. The initial guess is increased with 0.5 units to a maximum of 12 until convergence is achieved for the specific layer. However, simulations are stopped after 10 unsuccessful re-runs to avoid infinite loops.

 

 Element names are now written in the Description column in the PG-files

 

 Elimination of several bugs in the interface between CoupModel and VMinteq, mainly concerning the treatment of special cases humic and fulvic acids.     DG