Many installations have 3D geometric models in file formats which can be directly used in FLACS. These existing CAD files can be imported into FLACS in two different ways: the first way is to import directly in CASD; the second way uses a command-line utility called geo2flacs. In this article we will discuss both methods, and list the geometry file formats that the FLACS tools can handle.
Geometry file formats for import
In general, the most suitable file types to import into FLACS are those which are volume-based, such as files from Microstation and PDMS. The import algorithms will not be able to interpret surface-based geometries properly.
You can import the following file formats:
- AVEVA RVM files (PDMS review / exchange file format),
- Microstation dgn versions 7 and 8,
- Prp files (Propagated steel, Frameworks format),
- AutoCAD (as DWG or when contained in a dgn file),
- StereoLithography file (STL).
Importing a geometry in CASD
The import GUI can be accessed from themenu in CASD:
Click on theoption in the menu to open the CASD Import window.
The graphical interface is divided into six sections as indicated in the above figure; these sections represent the following thematic clusters:
- In the first section, Input Geometry you locate the files to be imported.
- In the second section, you can transform the geometry: rotate it around the Z axis, translate it or scale it with a defined factor.
- In the third section, it is possible to filter out the small primitives based on the diameter of cylinders and the width of boxes (i.e. the second longest dimension). You can use this feature, for example, if you want to import objects of a defined size range, like cylinders above a certain diameter. This can be useful when the available CAD files are detailed down to bolts and nuts and these small objects are not considered valuable for FLACS simulations.
- In the fourth section, you define how you want to group the geometry objects. This can be done based on a combination of any of the following:
- the number primitives,
- the material (colour), and
- This feature is useful to organize the objects and limit the number of primitives in them. It allows you to group, for example, primary structure in separate objects from those of process equipment. A great example of the usefulness of this feature is a situation where you need to account for insulation material thickness around the piping. Having grouped the piping into one object, you can open this object and edit it, increasing pipe diameters to account for insulation material.
- In the fifth section, you choose how you would like to treat diagonal elements, i.e. those that are not aligned with the Cartesian axes. The two options are either to keep the elements diagonal (No Alignment) or align the element to the nearest axis (Align to Axis), which is the default.
Please read the Note about non-orthogonal elements and general Objects in the FLACS User’s Manual regarding the use of elements not aligned with the Cartesian grid.
- In the sixth section, you specify the location and the name of the new database or choose to connect to an existing database. Optionally, you may apply the Gexcon colour convention (cf. FLACS User’s Manual) to the geometry if it does not have any.
The button in the lower left corner of the window, gives access to advanced import options. You can use the advanced options, for example, in case you notice missing elements in the imported geometry. Please consult the FLACS User’s Manual for more information.
Importing a geometry with geo2flacs
To import a geometry my_geometry.dgn with geo2flacs and write it to a new geometry database called myDB run:
- on Linux:
run geo2flacs --database=myDB my_geometry.dgn
- on Windows:
geo2flacs --database=myDB my_geometry.dgn
The command line utility geo2flacs can be particularly useful for scripting and importing with special options. For additional advanced information, launch geo2flacs with its --help option or consult the FLACS User’s Manual.