GGU-2D-SSFLOW: Short description

As reading manuals is, from personal experience, a bit of a chore, there will now follow a short description of the main program functions. After reading this section you will be in a position to analyse steady-state groundwater flow. Worked examples and details can be taken from further chapters.

• Design the system you wish to analyse.

• Start the GGU-2D-SSFLOW program and go to the menu item "File/New". Answer the question of the "Common systems" dialog box with "No". Select the type of system which you would like to work with.

• If necessary, fit the page coordinates to those of your system. For this, use the menu item "Page size + margins/Manual resize (editor)".

• Then go to the menu item "Mesh/Define nodes".

• Click on the principal nodes (points) of your system with the mouse. The points will be numbered. Alternatively, you can also enter the system nodes in tabular form, using the menu item "Mesh/Change". When defining nodes in horizontal-plane systems, new nodes will be assigned default depths (top and base of aquifer), which may be edited with the menu item "z/Default depths".

• If the nodes are outside of the page coordinates, go to the menu item "Page size + margins/Auto-resize" or use the [F9] key.

• Now go to the menu item "Mesh/Manual mesh" and combine the nodes, in groups of three, to triangular elements. In this way, you create a coarse structure for your system. Alternatively, you may have the program do this work for you, using the menu item "Mesh/Automatic".

• If you would like to edit the positions of mesh nodes, go to the menu items "Mesh/Change", "Mesh/Move" or "Mesh/Edit".

• If, for horizontal-plane systems, you would like to edit the positions of top and base of aquifer, use one of the menu items "z/Individual depths", "z/Modify" or "z/In section". Using "z/Layer boundary contours", you can get an overview of the positions of the top and base of the aquifer.

• If you would like to delete a triangular element, go to the menu item "Mesh/Manual mesh" again and click on the corner nodes of the appropriate element. Using this menu item, try double-clicking in a triangular element.

• The screen contents can be refreshed at any time using [ESC] or [F2].

• Create a fine structure for your system using the menu items "Mesh/Refine individually", "Mesh/Section" or "Mesh/All".

• Even after a mesh refinement, you can alter the system as you wish using "Mesh/Define nodes", "Mesh/Manual mesh", etc.

• For demonstration purposes, create one or more acute, and therefore numerically unfavourable, triangular elements using the menu item "Mesh/Move". Then go to the menu item "Mesh/Optimise" and follow the effects on the screen.

• Define the governing boundary conditions for the system using, e.g., the menu item "Boundary/Individual potentials".

• Edit, if wished, the soil numbers using the menu item "Boundary/Individual soils".

• Edit, if necessary, the soil properties using the menu item "System/Soil properties".

• When you have completed mesh generation, go to the menu item "System/Analyse" and begin the analysis. Before analysis starts the program will, if necessary, automatically carry out a bandwidth optimisation, in order to achieve a numerically favourably configured equation system.

• After analysis is complete you can, if wished, have the results printed as an output table, saved to a file or presented in a window (menu item "File/Print output table"). In general, however, this kind of result presentation will not very be satisfactory for the client.

• For this reason, you should immediately go to the "Evaluation" menu. The menu item "Evaluation/Coloured" is especially impressive or, for horizontal-plane systems, the menu item "Evaluation/3D array". The dialog boxes which follow can almost all be exited via the "OK" button, without further changes having to be made. The program usually makes sensible suggestions. Only the "Determine extreme values …" button should be clicked once, otherwise an error message will appear, with a correction note.

• If you have a colour printer installed you can point to the menu item "File/Print and export" and then the "Printer" button in the following dialog box, in order to get colour output to the printer. Grey scale will be used for black and white printers.

• Experiment with the example datasets.

This short description demonstrates that only a few menu items must be selected in order to analyse a groundwater system. All further menu items are mainly for data saving, layout and any further evaluation of the analysis. A description is given in the following chapters.