Micro-FEM is the original DOS version of MicroFEM for Windows. It is an integrated large-capacity finite-element microcomputer program for multiple-aquifer steady-state and transient groundwater flow modeling
The DOS package of Micro-Fem is a set
of several programs which takes you through the whole process of
groundwater modeling, from the generation of a mesh through the stages of
preprocessing, calculation, postprocessing, graphical interpretation and
Confined, semi-confined, phreatic and leaky
multiple-aquifer systems can be simulated with a maximum of 16 aquifers.
The maximum number of nodes is 12.500 nodes.
No limitations are set to the
number of wells. One of the outstanding features of Micro-Fem is the
user-friendly interface. Full graphics control makes the otherwise
time-consuming and error-prone process of model parameter input easier.
The same is true for the interpretation of the results; the visualization
of contours, flowlines, flow vectors, etc. is achieved with just a few
keystrokes. Results can be saved in the HPGL and DXF format.
Its capacity, flexibility and ease of use have made Micro-Fem the most widely used groundwater modeling package in the Netherlands. Its users comprise government agencies,consultants and universities.
To allow the largest possible models to run on a microcomputer, making full use of the computer's memory, the modeling procedure has been split up into several well-defined parts and related programs. The core of Micro-Fem consists of FeModel, a fully interactive graphics input/output program with a built-in calculation module.
MicroFEM modeling features
|saturated flow, single density|
|multiple-aquifer systems and stratified aquifers|
|confined, leaky and unconfined conditions|
|steady-state and transient flow|
|heterogeneous aquifers and aquitards|
|spatially and temporally varying wells and boundary conditions|
|spatially varying anisotropic aquifers|
|hydraulic heads and water balances|
|2-D and 3-D flowlines with travel times|
DOS System Requirements
|DOS operating system|
|VGA, EGA screen|
|color monitor recommended|
|extended memory recommended||
Program Features and Capabilities
|graphical user interface|
|easy data manipulation|
|interactive assignment of spatially varying properties|
|interactive visual error checking|
|up to 16 aquifers or sublayers|
|up to 12.500 nodes for each layer|
|mesh generator for regional flow models|
|high contrast mesh generator for civil engineering models|
|interactive mesh design and adjustment|
|user assigned names for all nodes|
|any number of wells|
|flow vectors and flowlines, 3-D particle tracking|
|water balances for each aquifer, subarea and time step|
|transferring existing model properties to a new mesh|
|transient flow modeling in batch or command mode|
Inner workings of the modeling procedures
|FemGrid||The program FemGrid is a mesh-generating program within Micro-Fem. It generates a triangular irregular network with variable spacing, based on a subdivision of the area into irregular polygons with uniform internal node-spacing. FemGrid is suitable for irregular geometries which are often encountered in regional studies (e.g. meandering rivers).|
|FemMesh||The program FemMesh is an alternative mesh-generating program within Micro-Fem. Like FemGrid it also generates triangular irregular networks with variable spacing. FemMesh is based on a subdivision into triangular and quadrangular areas with gradually changing nodespacing. FemMesh is useful for problems which require high contrasts in spacing (for example, sheet piling or excavations).|
|FeModel||The core of Micro-Fem consists of FeModel, a fully interactive graphics input/output program with a built-in calculation module. As a preprocessor it offers the possibility to add and (re)move nodes at any time and it allows the graphical, interactive input of model-parameters. |
The postprocessing capabilities include all kinds of contour maps, flow-vectors, flowlines and water budgets
|FemInvs||The program FemInvs was developed to automatically calibrate steady-state models (inverse modeling). The program adjusts the selected model input data to reduce the differences between observed and computed heads. The model may consist of 16 aquifers and EM version can handle up to 12500 nodes. Anisoptropy in all layers is allowed.|
|FemCat & FemCurv||The program FemCat handles transient calculations. A FeModel-file with the initial conditions and files with the storativities for each aquifer must be prepared. One or more time periods and the number of time steps can be specified. |
The program FemCurv visualizes the time-head files written by FemCat. Time-head or drawdown curves and time-distance profiles with various drawing options are among the possibilities. It also writes HPGL-files that can be plotted or imported by wordprocessors.
|FemPath & FemProf||The program FemPath is a three-dimensional particle tracking program which interprets a FeModel-file using additional aquifer and aquitard thickness data. Flowlines run forward or backward, starting at any node, in any aquifer and at any depth. The number of flowlines is unlimited. Fempath can be activated from FemCat to create coupled steady-state and transient pathlines. The program FemProf draws isohypses and flowlines in a vertical cross-section. |
|FemPlot||The program FemPlot plots map views, generated by FeModel and by FemPath, and writes HPGL and DXF-files. |
The modeling procedure consists of the following parts:
Finite element grid generation
Plotting and interfacing
Finite element grid generationFemGrid and FemMesh are
the mesh generating programs of Micro-Fem. Both make triangular irregular
networks with variable spacing.
FemGrid generates a mesh based
on a subdivision of the area into irregular polygons with uniform internal
node-spacing. FemGrid is suitable for irregular geometries which are often
encountered in regional studies (for example, meandering rivers).
FemMesh is based on a subdivision into triangular and quadrangular
areas with gradually changing node-spacing. FemMesh is useful for problems
which require high contrasts in spacing (e.g. sheet piling or
PreprocessingFeModel is both the pre- and the
postprocessor of Micro-Fem. As a preprocessor it offers the possibility to
add, move and remove nodes at any time and it allows the graphical,
interactive input of model-parameters. You "walk" from node to node with
the arrow keys and enter or change model parameters on the fly. You can
also define an area by "walking and marking" along its boundary. It is
possible to enter labels and parameters for a node, a group of nodes, an
area or the whole model at once. FeModel is able to assign values to the
model parameters by evaluating functions and expressions; a wide variety
of variables and standard functions is incorporated. Interesting
possibilities arise by making values a function of distance or position.
To check the entered data FeModel draws colored maps of the model
parameters and shows the minimum and maximum values on the screen.
Steady-state modelingBoth FeModel and the stand-alone
finite-element program FemCalc can calculate the steady-state heads and
prepare results for postprocessing by FeModel or FemPath. Generally
calculation times are short: a steady-state model of moderate size (e.g.,
three aquifers and 4000 nodes) takes less than 1 minute on a 66 MHz
PostprocessingFeModel's postprocessing capabilities
include fast and easy construction of maps of flow-vectors, heads,
drawdowns and the vertical flow components for every aquifer. Flowlines
can be drawn up- and downstream, indicating travel times. Water balances
can be computed for any selected node or area of the model. The FeModel
options will be adequate for those occasions where only the distribution
of heads and water balances are the objective of the modeling study.
Transient modelingTransient calculations are handled by
A FeModel file with the initial conditions and files
with the storativities for each aquifer must be prepared. One or more time
periods and the number of time steps for each period can be specified. At
each timestep FemCat allows changes in pumping, boundary heads and all
other parameters. The number of time periods is unlimited. For selected
nodes heads can be saved in a special file for each time step. FemCat also
offers the user other features: in phreatic aquifers seepage to surface
water can be modeled, and after each time step transmissivities can be
adjusted to the calculated height of the water table.
Anisotropic transmissivities can be incorporated for each node and
FemCurv is the program that visualizes the
time-head and flux data written by FemCat. Time-head or drawdown curves
and time-distance profiles with various drawing options are among the
possibilities. It also writes HPGL-files that can be plotted or imported
by word processors.
Plotting and interfacingGraphical output from all
Micro-Fem programs can be plotted on a HP-compatible plotter or translated
to HPGL or DXF graphics files by FemPlot. FeModel and FemPath save
different types of ASCII-files with model data for easy interfacing with
geographic information systems (GIS) and database programs. FemCat files
can also be loaded by a spreadsheet program.
Automated calibrationFemInvs was developed to
automatically calibrate steady-state models (inverse modeling). The
program adjusts the selected model input data to reduce the differences
between observed and computed heads. The model may consist of 16 aquifers
and can handle up to 12.500 nodes. Anisotropy in all layers is allowed.
Since hydraulic properties usually vary from node to node and since the
number of parameters to be optimized is limited to 40, it is not the
hydraulic properties themselves that are calculated, but rather the
corrections to these properties. For each parameter a subarea has to be
selected for which the correction will be computed. When referring to a
transmissivity, a hydraulic resistance or a discharge, the correction is a
multiplication factor that is applied to all values in the selected area;
when fixed heads are optimized, the correction is added to the original