New to FDS

[MechAustin]

For the past two weeks, I've been learning FDS for research purposes. I have looked at several YouTube videos and other tools, but I still can't figure out how to model prairies on terrain or model a wind profile (vector fields).

Specifically, I am stuck on:

Grasslands: Is there a standard way to apply grass properties to terrain surfaces (using &SURF)?

Wind: Is there a way to import GIS vector fields directly, or do I need to convert them into &WIND ramps manually?

If anyone knows about these or can point me to a good example file, please help!

[mcgratta]

There are two very different approaches to modeling wildfire in FDS. The first involves using particles to represent vegetation over domains that are hundreds of meters on a side. The second involves empirical spread models for domains that are tens of kilometers on a side. Which is your preference?

In any case, you can look at simple examples called CSIRO_Grassland_Fires whose input files are here. These cases are discussed in the FDS Validation Guide.

[mcgratta]

If you want to set up files like this for yourself, you need to install QGIS, install the qgis2fds plug-in, and then load the file QGIS_Files/Level_Set_Demo.qgs that lies in the folder parallel to FDS_Files.

[mcgratta]

I will add to the README with more details.

[mcgratta]

I added a few additional links to that README file. The short answer to your question is that there is a separate program called qgis2fds that is a plug-in to QGIS. So you need to install QGIS, then the plug-in, then import the .qgs file that I used to create the FDS input file you ran. Those two files, Landfire.gov_F13.csv and Level_Set_Demo_Wind.csv are located in the QGIS_Files folder. They are needed to generate the FDS input file, but once the input file is made, you do not need them to run FDS.

[MechAustin]

I just reviewed the windsmv file and noticed it is formatted as a table. Could you explain the process for generating one of these files?

[mcgratta]

I am not sure what you mean by the "windsmv file". In any event, most supplementary text files are .csv or comma-delimited text files. They appear on your computer, probably, as an Excel file because that is a common way to read them. .csv is a common format and easy for any program to parse.

[MechAustin]

Hello Mr. McGratta,

I have been able to use the QGIS software to simulate fires, but I am confused about a few things. For example, the image at the bottom shows the elevation raster layer and the fuel raster layer. My main question is: when I set the texture layer to the satellite image in QGIS, why does it not appear in the simulation?

Another question I have is about the fire layers. They only display the fire within the defined layer and do not show the fire spreading to the surrounding area outside of that layer. I thought the purpose of the simulation was to model how the fire would spread beyond the initial fire layer.

[emanuelegissi]

If your question regards qgis2fds , maybe it's better to continue this discussion on the dedicated forum:
https://github.com/firetools/qgis2fds/discussions

Please, open a new discussion there and attach a simple case that describes your issue so that I can reproduce it on my computer.

Thank you

[mcgratta]

The satellite texture map is not shown by default in FDS/Smokeview. You need to ask for it via Show/Hide. The reason is that the texture map makes the scene move more slowly.

As for the fire not spreading, I do not understand the question.

[MechAustin]

Hello Dr. McGrattan,

I am currently working on reproducing the level_set_demo from scratch. However, I have noticed that my generated FDS input file is significantly larger and contains much more code than the original example file.

Could you provide some insight into why my generated file is so much more verbose, and do you have any advice on how I can streamline it to better match the original?

Thank you for your time.

ARTest1.txt

Level_Set_Demo_1.txt

[mcgratta]

You are representing the terrain using OBSTructions. The Demo uses the GEOM complex geometry feature.

[MechAustin]

I see the difference now. Since I'm using QGIS to handle the terrain, I've been getting a long list of obstructions. To match the demo, should I be using the plugin to produce a single GEOM entry, or is the GEOM feature usually handled by referencing an external CAD/triangulated surface file?

[mcgratta]

qgis2fds provides an option to render the terrain using OBST or GEOM