|Groundwater modelling with MicroFEM • Lesson 1A: A simple finite element grid|
First a bit of explanation:
Text in bold means that your action is required.
Menu bar: Help / Info / About MicroFEM ... / [OK] means that you have to do a number of actions:
Any [text] between square brackets means that you have to click on a button.
Double click the yellow MicroFEM icon.
A window opens with, from top to bottom:
Step 1: Create an extremely simple grid (mesh, network) of only six equilateral elements
Menu bar: Files / New grid ... / select Create New grid / Irregular boundary grid (FemGrid) / [OK]
Enter the Model name in the upper cell: "Lesson 1" / [OK]
Only the Model name is required, but you may enter more information (Project, Location, etc.). The pop-up window disappears and we are now in one of the two "Grid generation modes". At the right-hand side an empty table (with the tabs: Fixed nodes, Segments and Regions) has appeared. Also, in the lower left corner, a Toolbar with some coloured buttons has appeared.
Place the arrow cursor above each of these buttons one-by-one, and read the texts shown in the small yellow pop-up windows.
We call such texts the "hint" of a button. One button is much larger than the others. It shows the hint: "Next generation step (F8)".
I call this button "F5". Clicking on this button has the same effect as pressing the F5-key on the keyboard.
Toolbar: [F5] / [OK]
Toolbar: [F8] / [F8] / [F8] / [F8] / [F8] / [F8]
Note that each time we click on the F8 button (or press the F8 key), the text on this button changes. A simple finite element grid has been built on the map.
Click on the cells in the table and look at the corresponding nodes in the map.
How large is the grid from West to East? And from North to South?
This saves all information of the generated grid to a Finite Element Network data file (a "fen-file"). We have finished with the grid in "Grid generation mode" and now can move on.
Toolbar: [F10] / [OK]
During this step we have to choose the number of aquifers of our model and accept the suggested number of aquifers = 1.
Intermission: Stop, save and start
This is the end of Lesson 1A. Suppose you would like to stop for today.
Menu bar: Files / Exit
A pop-up window appears with the question: "Do you want to save changes to Base model?".
This allows you to save a file "Lesson 1.fem". After that, a similar pop-up window will ask: "Do you want to save changes to Project? (Lesson 1.fpr)".
When you want to start again, there are different possible ways to continue:
In all cases MicroFEM will be started.
The fpr-file (project file) tells MicroFEM to open all model files: in this case it is only the Base-model: "Lesson 1.fem".
Many MicroFEM models also require additional information, saved in additional files.
The fen-file (network file) only contains grid information. When you start with a fen-file you are asked to enter the number of aquifers of the model. A fen-file can also be used to repeat the grid generating process with modified data. In the latter case, the file must be loaded from the Menu bar:
Menu bar: Files / New grid ... / Open existing network file with / Appropriate generator / [OK] / Open