search

firemodels / cfast

Consolidated Model of Fire and Smoke Transport
Other
68 stars 65 forks source link

Extremely High Target Heat FED #2055

Closed omarroq closed 7 months ago

omarroq commented 1 year ago

Hello!

I am currently running simulations with the goal of conducting tenability assessments at different compartments. An issue I have been encountering is that the Target Heat FED quickly increases and eventually reaches around 9000. I would appreciate any guidance and/or clarification on why this occurs.

I have attached the input file below.

Thank you.

HighFED.zip

preneke commented 1 year ago

I can verify that 187.3 s into the simulation, for no apparent reason, increases massively. I will take a look into this.

Paul

rpeacoc commented 1 year ago

Try running with a very small time step. Because the target flux is an explicit solution, the model can it too large a time step in rare instances and lose a good solution.

preneke commented 1 year ago

Your values for the "Human" target do not seem correct. I can't provide you with correct values but you should check them. I would also strongly suggest you use a much thicker target. I am assuming you are interested in the impact of the heat on a living being and people are not 0.1 mm thick and that extra thickness has impacts even on the surface. It definitely can have an impact on the numerics in CFAST.

preneke commented 7 months ago

This seems to run fine in CFAST 7.7.4. There was a bit of confirmation bias on my part. At 180 s into the simulation the upper layer in the compartment is 150 C and increasing. FED is not calibrated after 1 since that is when the heat, in this case, is deadly. I am going to close this and if there are any other problems please go to the discussion or start a new issue.