Importing FDS Validation Examples into PyroSim

The FDS validation suite compares FDS (Fire Dynamic Simulator) results with experimental data. These examples cover most of the features of available in FDS. When you want to use a new feature in FDS, you can speed your learning by reviewing how the feature was used in a validation example. This post shows how you can quickly import the FDS model into PyroSim.

Either watch the video or skip to the text below.


To download the NIST Validation Guide, go to Click Downloads and then click FDS Validation Guide. Read the guide and find a problem that you would like to run. Here is an image showing some of the content of the guide, as you can see these are useful examples.

Partial contents of NIST Validation Guide

Once you decide on a problem, download the FDS input file. To do this:

  • From an FDS-SMV page, click View on GitHub. This will open a new web page.

  • Click the Validation folder. This will display a list of validation problems.

  • Find the problem you want to use. The name typically is the name of the experiment used to obtain the results. For this example, we will select the first example ATF_Corridors
  • Click the FDS_Input_Files folder.
  • Click the specific case you want to run. We will select the ATF_Corridors_240_kW.fds case. This will open a listing of the input data. 
  • Click to select the Raw view.

  • Save the raw file as an FDS input file. In this case, we give the name ATF_Corridors_240_kW.fds.

Now start PyroSim.

  • On the File menu, click Import FDS/CAD File. Select ATF_Corridors_240_kW.fds. Select the FDS version, in this case FDS6, and click OK. This will start the import process.
  • PyroSim supports most FDS options directly in the user interface, however, there are some less frequently used options that must be input manually. Nearly all input dialogs include an Advanced tab, where the user can type the parameter name and value in the Additional Fields section. PyroSim then includes this data when writing the input record. During file import, a warning message will be given for any field that was not supported and what action was taken by PyroSim to resolve the issue. In this example, the fields SIG_FIGS, SIG_FIGS_EXP, NO_SLIP, and VELO_INDEX are not supported. PyroSim added the parameters to the Additional Fields section. Click OK to close the FDS Import Warnings dialog.

  • The gas velocity measuring device H-01 included the VELO_INDEX parameter. In the figure below, we see that the parameter was added to the Addition Fields section and is written as part of the FDS input record.

The model Record View displays highlighted records of the input file that will be sent to FDS.

Model Record View showing the input data written for FDS execution

Here is a picture of the imported model, ready for simulation. Since there are three meshes, we can speed the solution by using clicking Run FDS Parallel on the Analysis menu.

3D View of model

Cut/Paste option: In the raw view, you could copy the records then click on PyroSim and paste. You can also copy/paste between PyroSim models.

Comments or Questions

This post was written by Daniel Swenson. For comments or questions, send email to

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