SMS:GFGEN Executable Known Issues

Unfortunately there are some known issues and likely some unknown issues as well related to the GFGEN executable. This page is intended to help brings awareness of known issues and how to work around them.

GFGEN (TABS) is developed by Resource Management Associates, Lafayette, California, and modified by WES. Aquaveo does not have access to the GFGEN source code and cannot make changes to fix the issues found in the GFGEN numerical model. Aquaveo can fix problems in the SMS interface, used for pre and post processing of GFGEN files.

This list may not contain all know issues, so please feel free to add to it.

Node Location Truncation

GFGEN does not correctly calculate the midside node location if the x or y coordinate of a node are large. Errors may be similar to the following:

* Node     50 Violates MIDDLE THIRD RULE ***** 
The node lies       0.0831 of the way from node      1 to node     49 

=== Problem inside COEFS routine. Do 180. 
Element= 535 Gauss pt= 1 out of NGP= 16 
Divide by DETJ= -0.0229 
J11-J22-J12-J21= 1.1526 0.38006 0.74030 0.62257 
stop in coefs 

The current work around is to translate the mesh so the x and y coordinates are smaller values.

See the following forum posts:

• RMA2 – same mesh, same BC, different results?, Results differ depending on nodal coordinates
• Problem inside COEFS routine

Element Limit

GFGEN can only handle up to 100,000 elements.

Related Topics

• GFGEN