GGU-3D-TRANSIENT: Preface

The GGU-3D-TRANSIENT program allows modelling of transient groundwater flow in three-dimensional groundwater systems using the finite element method. The program includes a powerful mesh generator and routines (contours, 3D graphics, etc.) for comfortable evaluation of the modelling results.

The program includes convenient data input. The system is permanently displayed on the screen. Every change to the data is displayed on the screen, so that optimum control of the input data is guaranteed.

There are "?" and "Info"’ buttons in the dialog boxes for many technical and program-specific questions. Click on the "?" buttons or "Info" buttons to obtain the necessary information.

The graphic output supports the true type fonts provided by WINDOWS, so that an excellent layout is guaranteed. Colour output and numerous graphic formats (BMP, TIF, JPG etc.) are supported. PDF and DXF files can also be imported via the integrated Mini-CAD system (see "Mini-CAD" manual).

The program has been extensively tested. No errors have been found. Nevertheless, liability for completeness and correctness of the program and the manual, and for any damage resulting from incompleteness or incorrectness, cannot be accepted.

It is not the aim of this manual to offer an introduction to the finite-element method. For details of the finite-element method, please see O. C. Zienkiewicz, "Methode der Finiten Elemente" ("Finite-Element Methods"), Carl Hanser Verlag Munich Vienna, 1984. The hydraulic basics used in the FEM program can be taken from, e.g., J. Buß "Unterströmung von Deichen" (Announcement 92, Leichtweiß-Institut, TU Braunschweig).

The following general notes are important:

• The data basis is represented by steady-state systems imported from the
  GGU-3D-SSFLOW program.

• Triangular elements are used.

• Darcy's Law applies.

• The piezometric heads are calculated in a linear manner for each element.