Conversion FDS files

[Fabia Schirinzi]

Good morning, I need help regarding the conversion of fds output files. In particular I would need to transform the file containing the surface deposition data (.bnd or .bf?) into a text file (ASCII) to be used on the Fluka software. I tried looking at github, but I'm having a hard time understanding what I need to do. Thank you!

[Kevin McGrattan]

You can try using fds2ascii. Search the User's Guide for details.

[Fabia Schirinzi]

Good morning, I tried to convert a test file using fds2ascii. The file is divided into two meshes and is the one attached. Assuming I wanted to know only the WALL TEMPERATURE, I followed this procedure:

 Enter Job ID string (CHID):
prova5
 What type of file to parse?
 PL3D file? Enter 1
 SLCF file? Enter 2
 BNDF file? Enter 3
3
 Enter Sampling Factor for Data?
 (1 for all data, 2 for every other point, etc.)
1
 Domain selection:
   y - domain size is limited
   n - domain size is not limited
   z - domain size is not limited and z levels are offset
   ya, na or za - slice files are selected based on type and location.
       The y, n, z prefix are defined as before.
y
 Enter min/max x, y and z
0 12 0 19 0 4
 1   MESH  1,  WALL TEMPERATURE
 2   MESH  1,  TOTAL HEAT FLUX
 3   MESH  1,  RADIATIVE HEAT FLUX
 4   MESH  1,  HEAT TRANSFER COEFFICIENT
 5   MESH  2,  WALL TEMPERATURE
 6   MESH  2,  TOTAL HEAT FLUX
 7   MESH  2,  RADIATIVE HEAT FLUX
 8   MESH  2,  HEAT TRANSFER COEFFICIENT
 Enter starting and ending time for averaging (s)
0 900
 Enter orientation: (plus or minus 1, 2 or 3)
1
 Enter number of variables
1
Enter boundary file index for variable 1
1
Enter output file name:
prova5ascii2.csv
 Writing to file...      prova5ascii2.csv
Stop - Program terminated.

I can't understand the organization of the .csv file obtained. What are "patches"? How are they organised?

[dr_jfloyd]

The bf file format is discussed in 26.11 of the User's Guide. A patch is a rectangular group of wall cells in a single orientation. If you had a domain that had a single OBST inside the domain, then there would be 12 patches total in the bf file -- one patch for each of the six faces of the OBST and one patch for each exterior boundary.  fds2ascii writes a csv file for one orientation at a time which means the csv file would have two patches.  FDS builds the list of patches inside the domain by looping over the OBST in the order they are defined in the input file.

[Fabia Schirinzi]

Ok, I think I understand. But does this mean that, if I have to recreate this scenario in 3D on another software by reporting the data obtained, I have to create an ascii file for each orientation? Or would only what I obtained in this case be enough for me?

[dr_jfloyd]

You would need to run fds2ascii for each orientation you plan to make use of in the other software program.

[Jonathan Hodges]

You could try using pyfdstools to streamline this process. The example linked below will query an axis and location value from the binary files and return a 3-D array of the data (axis1, axis2, time). What is the format of the ASCII file that your software is expecting?

https://github.com/johodges/pyfdstools/blob/master/pyfdstools/examples.py#L136

[Fabia Schirinzi]

A specific format is not necessary, I would only need a numerical value (specifically it would be the surface deposition, the file I sent you was a test) for each cell of the space. For this reason I would like to be able to understand if it is necessary to create an ASCII file for each orientation or if, to reconstruct my scenario, I just need to consider a single orientation and orient myself based on that to enter the data.

[Jonathan Hodges]

Take a look at the two boundary examples in pyfdstools. You should be able to use one of them to accomplish your goal.

exampleImportBndf - This one will import the boundary data at a specific axis location. By default it will time average it and plot it, but once you have it in memory you can dump the data to a csv. This function can be a bit of a pain to work with since it is looking for an exact axis position. You will need to know the axis position that the OBST snapped to on the FDS grid rather than what you specified in the input file.

exampleExtractBndfMax - This one will extract the max value on an obstruction with time and save it to a csv. You can limit to only specific orientations as well, so you could run it 6 times to get the max value with time on each orientation independently.