GGU-3D-SSFLOW: Short description

Since I know from personal experience that reading user-manuals is quite a chore, there will now follow a short description of the main program functions. After studying this section, you will be in a position to model steady-state three-dimensional groundwater flow. More detailed information about the program can be obtained from the subsequent chapters as you require it.

• Design the system to be modelled.

• Start GGU-3D-SSFLOW and go to the "File/New" menu item. If you do not wish to proceed via "Common systems" answer no to the question and enter the number of element layers. This can be increased or reduced later.

• If necessary, adjust the sheet coordinates to fit your system. Use "Page size + margins/Manual resize (editor)" to do this.

• Then go to "Mesh(x/y)/Define nodes".

• Using the mouse, click the governing nodes (points) in your system. The points will be numbered. Alternatively,  you can also enter the nodes in tabular form using "Mesh(x/y)/Change". Each newly generated node is awarded the values entered in "z/Default depths" as z ordinates. During and after mesh generation, you can edit the z ordinates associated with a node at will (see below).

• If the nodes lie outside of the visible sheet coordinates, go to "Page size + margins/Auto-resize" or press [F9].

• Now go to "Mesh(x/y)/Manual mesh" and unite groups of three nodes to single triangular elements. In this manner you generate a rough structure for your system. Alternatively, by using "Mesh(x/y)/Automatic", you can have the program do this work automatically for you. During automatic mesh generation the triangular prisms are assigned the default soil column for all new triangular elements. The default soil column defines the soil numbers of the individual triangular prisms. The soil numbers can also be subsequently edited at any time.

• If you want to edit the positions of mesh nodes, select one of the menu items "Mesh(x/y)/Edit", "Mesh(x/y)/Change" or "Mesh(x/y)/Move".

• To define the depths of the planes, enter the plane surfaces in the "z/Default depths" menu item.

• If you want to delete a triangular element, select the "Mesh(x/y)/Manual mesh" menu item once again and click the three corner nodes of the corresponding element. After selecting this menu item, try a double-click in a triangular element.

• You can refresh the screen at any time using [Esc] or [F2].

• Turn your rough structure into a fine structure by using the menu items "Mesh(x/y)/Individually refine" or "Mesh(x/y)/Section" or "Mesh(x/y)/All".

• After mesh refinement, you can still edit your system at will using "Mesh(x/y)/Define nodes", "Mesh(x/y)/Manual mesh", etc.

• For demonstration purposes, use the menu item "Mesh(x/y)/Move" to generate one or more acute, and thus numerically unfavourable, triangular elements. Then select the "Mesh(x/y)/Optimise" menu item and follow the effects on the screen.

• Previously, each node was assigned the default depths during mesh generation. If you want to see your mesh in a vertical section, use "z/Define section" to define a section through the system.

• Use "Boundary/Individual potentials", for example, to define the boundary conditions governing your system. A potential can be assigned to the node in the current plane or to all nodes associated with this point.

• You can move through the planes using the und tools, which you can find in the 3D toolbar at the lower left of the program window. The active plane and the active layer, in which you now find yourself, is shown in the Layer/plane legend.

• If you wish, you can edit the soil number using the "Boundary/Individual soils" or "Boundary/In section" menu items. Every soil number can subsequently be assigned different soil properties. The soil numbers defined refer to the current layer.

• If necessary, edit the soil properties using the menu item "System/Soil properties".

• Once you have completed mesh generation, go to "System/Model" to commence modelling. Where required, a bandwidth optimisation will be carried out before modelling commences, in order to achieve a numerically favourable equation system.

• If wished for, you can send the results to a printer as an output table or write them to a file once modelling is finished. However, this method of result presentation is generally less than satisfactory to the client.

• So, proceed immediately to the "Evaluation" or "3D" menus. You can almost always leave the subsequent dialog boxes using the "OK" button, without having to make further changes. The program will usually suggest sensible input. The "Determine extreme values…" button, which appears in a number of dialog boxes, should be clicked once however, otherwise an error message will appear.

• Define a section (menu item "z/Define section") and then press [Return]. Now select the tool from the toolbar at the lower left of the program window. You will now see a cut-away of the system. You may rotate the system in steps around the z axis using the tool. Try pressing the [F9] function key (or use "Page size + margins/Auto-resize"). Change the current plane from the one you are now in.

• If you find yourself in a section and wish to return to a representation or evaluation in plan, go to "Mesh(x/y)/Mesh".

• If you have a colour printer correctly installed in WINDOWS, you can create colour output by going to "File/Print and export" and then pressing the "Printer" button in the subsequent dialog box. For monochrome printers, grey scales will be used.

At the end of this manual, the program is described using a comprehensive example. This short description demonstrates that only a few items need be selected to model a groundwater system. All further menu items deal principally with saving data, layout and further evaluation of the model, where required. The description is given in the following chapters.