DATA FORMATS
This article introduces common data file formats, describes appropriate map file usage and explains ways of exporting model data of different types.
FEFLOW file formats
FEFLOW utilizes three data formats:
1) .smhx or .smh3D for supermesh files
2) .fem for complete model data files including all imported map data
3) .dac files for simulation records
Supermesh files determine the model geometry and internal features such as model subdomains, surface water bodies, tectonic or anthropogenic structures. These can be defined as polygons, polylines or singular points. The supermesh file is an xml based data format and can store 2D data (.smhx) or 3D data (.smh3D).
Once the finite element mesh is created, the .fem data format is used. It contains mesh data, imported map data, parameter distributions, observation and time-series data for transient simulations. The .fem file is a comprehensive file type, comprising all relevant model data. It can be shared or copied without dependence on secondary parameter files. The .fem file is either ASCII or binary formatted.
In order to record the results and intermittent steps of simulation runs, the .dac file format is used. This file type is meant for any time-variant results analysis. It contains chart data, budget calculations and parameter distributions of any process variable and any or predefined time-steps.
All FEFLOW file types can be opened with either FEFLOW or the FEFLOW Viewer, while the latter does not require a license, no changes can be made to files.
Supermesh import
To start a supermesh project the user chooses to either import an existing mesh file or to import separate geometric features as points, polylines or polygons. Mesh files must contain a valid mesh description and can be imported for example from MIKE products (.mesh, .smesh), Leapfrog (.lfm), Geomodeller 3D (.gmod) or any object-based or stereolithographic files (.obj, .stl) - see Fig. 1. Please note that for unstructured meshing, file formats are limited to Kitware formats (.vtu, .vtk) and Geomodeller 3D (.gmod).
Fig. 1 – Data formats for import of meshing files or geometric data to build a FEFLOW supermesh.
Any other geometric data can be loaded as either triplet or tabular data containing X,Y,Z coordinates (.trp, .dat, .pnt, .xlsx, etc.), as 3D model or surface data from AutoCAD or GOCAD (.dwg, .dxf, .ts) or vector-based polygon, polyline or point shapefiles (.shp). Such data have to be converted into supermesh items before discretizing with one of the internal meshing algorithms. It is recommended to work with vector data (.shp), due to best performance regarding data interpretability and meshing stability.
CAD data in .dxf format often contain diverse geometrical data types that may lead to inconsistent meshing operations. Please make sure to filter .dxf files for information that is required to represent relevant geometries before importing them into FEFLOW. Be aware of using arcs instead of chains of polylines to represent curvilinear features and avoid overlapping polygons.
Data import as maps and time-series
Maps can be used to assign spatially distributed parameters or boundary conditions. The maps panel allows to import any of the above mentioned geometric data formats (Fig 1) at any stage of the modeling process. The coordinate information needs to be complemented with the respective parameter data such as hydraulic heads, pump rates or concentration data. Most datasets are either rasterized or sampled data and need to be interpolated for the nodes in between the data points. It it best practice to prepare datasets as distributed point datasets (triplet data or point shapefiles) and use IDW or Kriging regionalization to assign parameter data to all model nodes or elements.
In FEFLOW no raster data formats can be read, processed or used for parameter assignments. They are only meant to visualize data like topographic maps or orthophotos.
Time-series are formatted as power files with the ending .pow. Please refer to this article how to format it correctly KA-01155 - FEFLOW - Generation of Power Time-Series File. They can be imported or exported via the time-series editor - see Fig. 2.
Fig. 2 – Time-series editor with import and export functionality for power formatted files.
Export of parameters and process variables
Parameter distributions can be exported for the entire domain or a nodal/elemental selection. Process variables (hydraulic head or concentration) or boundary conditions are node-based and can be exported as point shapefiles (.shp), drawing data formats (.dwg, .dxf) or as tabular triplet data denoting X,Y,Z coordinates of each node (.trp, .dat, .pnt, .xlsx). Elemental data like material properties are exported as either patches, polygons, lines or center data - see Fig. 3. Such data are typically stored as drawing data formats (.dwg, .dxf) or shapefiles (.shp).
- Patches: one value per element as filled shape
- Polygons: zones with the same parameter value as filled shape
- Lines: edges of the mesh skeleton, for geometrical displays
- Center: Point data, one parameter value in the center of the element
Fig. 3 – Export of a time-variant material property (here: In-/outflow top/bottom) as patches for all elements and multiple time-steps.
In addition, FEFLOW allows to directly export fringes or isolines with pre-defined intervals from the 'View Components' panel. Fringes are saved as either Patches, Triangles or Points:
- Patches: see patches above
- Triangles: value per element
- Points: : raw results, value per node
Export of budget calculations
From the 'Rate Budget' panel the budget components can be exported with a right-click for the current time-step. If the user wants to export the budget for various time-steps, only the Period Budget can be exported; the .dac file needs to be used. Open the 'Period Budget' panel and define the final time-step for the calculation and add the checkmark on the Export option - see Fig. 4. FEFLOW will write all budget components for all time-steps in a separate ASCII formatted text file. This workflow can be applied for the entire domain or for any nodal selection which is saved in the 'Selections' panel.
Fig. 4 – Budget Period panel to export budget components for all time-steps from a .dac file.
An alternative to export budget time-series is the Budget History Charting accessible from the 'Selections' panel. For any given nodal selection the budget can be plotted and exported as charts showing either the entire rate budget or the individual budget components. Please refer to the following documentation pages how to correctly setup and use the Budget History Charting FEFLOW 10.0 - Budget History Charting.
Export of charts and curve data
FEFLOW offers a variety of charts to plot time-variant process variables like hydraulic head, concentration, heat budgets or budget history charts. The modeled curve data can be exported from the 'Chart Properties' window. The easiest way is to select the curves and copy them as Text as shown in Fig. 5. The data will be copied to the clipboard as text.
Fig. 5 – Data export of curve data from the Chart Property window.
Another option is to click the save button and choose from a selection of file formats. It is possible to export the data both, as vector data in .dwg, .dxf or .shp format or to use regular ASCII formatted tabular or text formats such as .txt, .dat, .xlsx or .pow.
FURTHER INFORMATION AND USEFUL LINKS
Manuals and Guidelines
FEFLOW 10.0 Documentation - Import of a 3D mesh
FEFLOW 10.0 Documentation - Maps Panel
FEFLOW 10.0 Documentation - Results Export
FEFLOW 10.0 - Budget History Charting