What is the MOFAT Pre-processor?
The MOFAT pre-processor was designed to write data files and store data for MOFAT numerical model runs. The pre-processor works in concert with the Mesh Editor and with the post-processor to make a complete graphical interface to the US EPA's Multiphase Organic Flow and Transport simulator. There are four distinct programs in MOFAT: the MOFAT numerical model, the MOFAT Pre-processor, the Mesh Editor, and the Post-processor. Each rely on one another for data input and output. For instance, the Mesh Editor is a dumb program that doesn't care whether it is working with MOFAT, or with BIOF&T, MOVER or MARS. It simply reads in a template file that lets it know what associations (for example, soil types, boundary conditions, etc.) are legal for MOFAT and what associations have been entered in the pre-processor for that mesh file. This arrangement allows for development of the Mesh Editor to include more features in the future without disturbing the main MOFAT program.
The MOFAT Pre-processor allows for entry of Control Parameters (for example, whether or not transport will be solved for in the run), Initial Conditions (initial heads of water and oil), Species Properties for up to five species, Fluid Properties, Transport Properties, Boundary Conditions, and Material Properties for up to ten soils. Many values entered in the pre-processor are used in the Mesh Editor. Values like non-uniform water heads are defined in the pre-processor, then later assigned to nodes in the Mesh Editor. Material Properties, Boundary Conditions, non-uniform oil heads, and individual node printouts are all assigned to nodes or edges in the Mesh Editor.
The MOFAT Pre-processor also has a run module for writing input data files and executing the MOFAT numerical model. It is important to understand that the pre-processor does not read MOFAT numerical model data files, it only writes them. The pre-processor and Mesh Editor use text files to save project data to disk and to open projects. After a data file for the numerical models has been written, you can change individual control parameters but these changes will not be reflected in the pre-processor.
The MOFAT Pre-processor Interface
After clicking on the MOFAT pre-processor for the first time, a setup notebook will appear on the screen. This notebook acts as a binder for all MOFAT data files, for links to the Mesh Editor and a project mesh, for writing input files and running the numerical model, and for cue cards and additional help. This notebook is available at any time by selecting Tools|Setup from the main menu or Tools|Runner. To prevent this notebook from automatically displaying every time the pre-processor is run, click off the Show Again check box on the Cue Cards page.
Note: all variable names like ITRN are in capital letters and match exactly the names used in the MOFAT FORTRAN source code.
The MOFAT pre-processor runs under Windows 3.X, Windows 95 and Windows NT. Currently all MOFAT programs are 16-bit, so there is no speed or multitasking advantage to running the programs under a 32-bit operating system. For most problems, the pre-processor will run well under 4 MB of RAM. When dealing with large finite element meshes, you will find that reading and writing files, and working with the Mesh Editor will greatly slow down under 4 MB of RAM. Also, the numerical model will not run under 4 MB of RAM for larger problems.
The MOFAT pre-processor uses a commonly-used tabbed notebook interface to allow quick editing of input files. The main program has two sets of tabs, one along the bottom which separates major sections of the interface, and, on some of the large notebook pages, tabs along the top that separate subsections to make the most use of available screen space. For example, clicking on the bottom tab "Boundary Schedules" takes you to the boundary schedule notebook. Here there is a tabbed notebook for editing type 1 and type 2 boundary schedules.
MOFAT for Windows does not have a pre-processor checklist or linear approach for a user to step through each necessary data input value. MOFAT starts up with default values selected for logic switches (for example, ITRN - solve for transport is default set to off), but data values are set to zero (for example, TH - time weighting factor). The MOFAT numerical model will not run if these data values are not input by the user. While the pre-processor will check to be sure that at least one soil type has been entered before running the numerical model, it will not check control parameter data values. While this method may lead to some misunderstanding for the beginning modeler, most who use the preprocessor more than a few times will appreciate not having dialog boxes pop up every time they don't want to enter a value for a variable.
Opening and Saving Projects in MOFAT
A MOFAT project is similar to a multi-table database. Data for the pre-processor is stored in ASCII text files as is data for the Mesh Editor and Post-processor. When a new project is created and saved to file, the pre-processor prompts you for a project name (an .mfp file extension is the default type). The pre-processor will then create sub-data files for species data and materials data.
What is the MOFAT Mesh Editor?
The Mesh Editor in MOFAT was designed to work with these numerical models to create and edit finite element meshes. The Mesh Editor allows designing irregular quadrilateral meshes in two dimensions and hexahedral meshes in three dimensions. MOFAT version 2.2 only uses 2D rectangular elements. Working with a numerical model pre-processor, the Mesh Editor provides a graphical interface for assigning properties to a mesh such as initial concentrations of contaminants, soil properties, boundary conditions, etc.
Panning allows the mesh to be moved in the Mesh Editor window. This puts the Mesh Editor into its pan state. You can then hold down the left mouse button and move the mesh on the screen. Letting go of the left mouse button "drops" the mesh in place. Nodes cannot be selected individually in this state.
The rotate button is the leftmost red button on the tool bar. It puts the Mesh Editor into a rotate state where the mouse can be used to rotate the mesh in three dimensions. The mouse will rotate the mesh on the XYZ axis intersection. Rotating the Mesh Editor takes a little getting used to, but if you ever get lost the handy X-Y, Y-Z, and Z-X buttons will snap the mesh back into place.
The rightmost red button called Node Control puts the Mesh Editor in its editing state. Now a node or group of nodes can be selected to have values assigned to them or be moved in the X, Y and/or Z direction. To edit associations (i.e., soil type, recharge zones, type-1 boundary conditions, etc.) for a node, select the node, then right-click the mouse. This will bring up a list of available associations. Clicking on an association will bring up a secondary list of associations that can be assigned to the node.