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 1 
 on: September 13, 2018, 02:05:49 pm 
Started by huyquangbkvnf - Last post by Charlie Thornton
The current version of Pathfinder includes additional support for monte carlo simulation. More information here:

https://www.thunderheadeng.com/2018/06/monte-carlo-simulations-in-pathfinder/

 2 
 on: September 11, 2018, 10:16:37 am 
Started by llammar - Last post by llammar
In our simulations of natural smoke and heat exhaust ventilation, we are regularly confronted to the question what we should indicate in our report as aerodynamic or geometric surface for the exhaust vents on the roof. What can be considered as a reasonable ratio between the surface of the exhaust modeled in FDS and the geometric and aerodynamic surface of an exhaust product. We are in general modelling the roof as a thick obstruction, and the exhaust as a hole in the roof with open boundary conditions over the roof.
What is generally considered to be the link between the size of the exhaust introduced in the FDS model and the aerodynamic surface or geometric surface? I assume that the effect of the "vena contracta" can be regarded as taken into account by an FDS simulation. What mesh size should here be considered?

 3 
 on: September 11, 2018, 03:27:00 am 
Started by UNDI - Last post by UNDI
Hello,

I ran a simulation about a burning chair ignite another chair.

According to the User guide, the mass flux was used for burner, but mass flux tab was in surfaces dialogue, can I use the ramp of mass flux and ignition temperature together to simulate the product after chair was ignited?

I tested the mass flux ramp, and if there is no heating source around, there won't be any species.

So my question is how to couple the ignition temperature and mass flux?



 4 
 on: September 08, 2018, 08:45:10 am 
Started by faker - Last post by jharbold
Perhaps look into justifying the use of a straight tunnel as opposed to incorporating the use of a non-straight model.

 5 
 on: September 04, 2018, 03:24:52 pm 
Started by faker - Last post by Jon Albrecht
Based on the question in your other thread, you are working with a version of PyroSim no newer than PyroSim 2012. That version of PyroSim supports FDS5. Over the last six years, FDS has continued to evolve as a simulator, adding to and improving upon the simulation tools offered six years ago. Simply put, you will not have much look trying to import an FDS file designed for the current simulator into a preprocessor designed for a six year old version of the simulator. You will need to either get the latest version of PyroSim or become comfortable working with FDS files without the convenience of a preprocessor.

 6 
 on: September 04, 2018, 03:12:15 pm 
Started by faker - Last post by Jon Albrecht
faker,

I am able to import and run your FDS model while working with our internal, nightly build. I'm afraid you will need to provide some more information about the versions you are working with, and what the expectation is.

On a very basic level, your MISC line is as follows:

&MISC Y_O2_INFTY=0.23/

Is the variable Y_O2_INFTY supported in the FDS version you are working with? Are any error messages or warnings provided when you import the FDS file? Each release of PyroSim only officially supports a single version of FDS, as the simulator continues to evolve side-by-side with PyroSim. While we attempt to simplify the use of FDS, it is ultimately the user's responsibility to understand the limitations of the simulator. Will look forward to a follow up.

Regards,

Jon

 7 
 on: September 03, 2018, 09:26:00 am 
Started by faker - Last post by faker
This is my source file.I came up with this problem when I imported the FDS file from the high version pyrosim and imported it into a low version.

 8 
 on: September 03, 2018, 08:56:16 am 
Started by faker - Last post by faker
When I run Pyrosim, it reminds me that "ERROR:Problem with MISC line",How to solve it?

 9 
 on: September 02, 2018, 06:38:49 am 
Started by faker - Last post by faker
When I used pyrosim to model curved tunnels, there were inevitably many zigzag obstacles due to grid size limitations, which made the simulation very slow.Do I have any way to simulate this model better?What is the use of "smooth" in obstruction properties?I hope I can get your help. Thank you.

 10 
 on: September 02, 2018, 06:35:37 am 
Started by faker - Last post by faker
The WIND namelist line was introduced in FDS 6.6.0 and is described in FDS User Guide Chapter 10. However, for modelling of tunnels I would suggest the method described in FDS User Guide Chapter 9.4. Using OPEN vents where you apply a dynamic pressure to the side where the wind enters the tunnel and on the opposite side you simply keep the OPEN vent as you described. This will create an airflow from one tunnel entrance to the other. This requires a little testing if you want to achieve a specific wind speed as it depends on how large the tunnel is and so on. I have achieved a wind speed of approximately 1 m/s with a dynamic pressure of 2,6 Pa, so I suggest using that as a very rough reference.
Thank you for your reply.I have another question I would like to ask you.When I used pyrosim to model curved tunnels, there were inevitably many zigzag obstacles due to grid size limitations, which made the simulation very slow.Do I have any way to simulate this model better?What is the use of "smooth" in obstruction properties?I hope I can get your help. Thank you.

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