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Messages - Jared

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16
You posted this on the Pathfinder forum instead of the PyroSim one - you may get more responses if you repost it there.  From my understanding, Run FDS Parallel is going to take all available computer resources to run your model.  By running a second model simultaneously, you are splitting your resources further.  You are likely better off running one model in Run FDS Parallel and then running the second one the same way.  Others may have better advice on this topic though..

17
PyroSim / Re: Carbon Monoxide Device Not Registering
« on: December 08, 2016, 08:50:53 pm »
Is it possible that the fire in the first model was perfectly ventilated and resulted in no CO production?

18
PyroSim / Re: heat flux
« on: October 17, 2016, 08:07:29 pm »
PyroSim is a third party user interface for Fire Dynamics Simulator (FDS).  FDS has a full verification and validation guide that is free online - do a google search for it.

19
PyroSim / Re: resume parallel simulation error
« on: October 13, 2016, 07:40:52 pm »
The restart function is extremely tricky within FDS.  PyroSim's restart function helps significantly with that, but if it isn't working I do not know of a work around.  In the meantime, I would recommend restarting the simulation from 0s and save it as a different name if you do find a way to restart the 300 s simulation. 

20
PyroSim / Re: Block obstruction via wall obstructions
« on: October 08, 2016, 11:57:33 am »
FDS treats them the same.  I would recommend making 4 walls, ceiling, and floor.  If you don't care about the material properties of the wall (i.e. you are going to make them adiabatic) then don't bother with walls and just make the mesh boundaries at your wall locations.

21
Pathfinder / Re: SFPE Mode V Steering Mode
« on: October 02, 2016, 10:27:29 am »
So SFPE mode and Steering mode are very different ways to calculate the time to egress from a building.  If you look into the SFPE Handbook, they developed a hydraulic model for egress.  Basically, this hydraulic model says it takes X time to move from your location to a door, Y time per person to move through that door, etc.  In this model it will move all occupants to an exit and allow multiple persons to occupy the same space while waiting to egress through the egress component.  From that point it will utilize a rate to determine how many people can move through that egress component per time.

The steering model is (I believe...) a Thunderhead developed algorithm that accounts for space of persons.  If you run both models and look at the results, you will see that the Steering model results in bunching and more realistic movement while the SFPE model allows the people to move in a straight line and occupy the same space.

It is your decision to determine which model is best.  Obviously you need to be conservative and defend this position either way.

22
PyroSim / Re: Extending Simulation time
« on: September 19, 2016, 08:32:37 am »
Yes that is possible as long as you only change things that are programmed to happen in the "future" such as simulation time.  The restart file will take an extremely long time to get going, but is likely worth utilizing instead of restarting.

23
PyroSim / Re: forrtl severe (157) program exception - access violation fds
« on: September 09, 2016, 08:26:08 pm »
Are you using pyrosim?  If you are using FDS, you will have better luck asking this question on the FDS forum.

24
Pathfinder / Re: Pathfinder and pyrosim - fire simulation
« on: August 25, 2016, 03:15:57 pm »
I may be wrong since I haven't used Pathfinder much in the past year or so and there may be an update, but I don't believe that importing the PyroSim model into Pathfinder will include the FDS results.  I think all that is doing is importing the geometry.  What you are going to need to do is understand through FDS what your tenability criteria are and when they are exceeded.  For example, you will look at FDS and say, "Room 101's tenability criteria are exceeded at 600 seconds."  Then you will look at Pathfinder and see if occupants are in room 101 at 600 seconds.

There should be a better way to do this, and I would imagine Thunderhead is working on it.  For now, I am not sure that it exists.

25
Pathfinder / Re: Pathfinder and pyrosim - fire simulation
« on: August 25, 2016, 02:54:05 pm »
What exactly are you trying to do?  These are 2 separate programs used for different types of analysis.

26
PyroSim / Re: Mechanical ventilation to evacuate smoke
« on: July 31, 2016, 11:15:44 am »
Dar123 is correct.  If you want to collect the smoke, use the HVAC tools.  Note that when you do this, smoke will instantly transfer between vents.  If you have vents which are 100m away from each other or 1m away from each other, the instant smoke enters the vent, it will be expelled at the other vent.

27
PyroSim / Re: Temperature, HRR not correct?
« on: July 31, 2016, 11:13:08 am »
The sprinklers will not have an effect on the HRR of a prescribed fire.  Each timestep, FDS is looking at your code to say, for example, at 100s the fire will be 1 MW, at 100.2s the fire will be 1 MW.

A conservative assumption is to run the model like you did, and then edit your HRR to stop growing at the point when the sprinklers activated.

28
PyroSim / Re: Numerical Instability
« on: July 31, 2016, 11:10:39 am »
Sorry for the late response.  When you get a numerical instability, smokeview will output a plot3d file for that last time step to help you figure out where the problem might be. 

29
PyroSim / Re: Numerical Instability
« on: July 11, 2016, 03:51:15 pm »
Does the Plot 3D output show anything for that timestep?

30
PyroSim / Re: Model a grille in a wall
« on: May 20, 2016, 06:37:26 am »
I have never really looked into it, but would a filter reduce the airflow?  What if you increased the friction loss on part of the HVAC duct?  Just some ideas..

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