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Messages - Jared

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31
PyroSim / Re: Model a grille in a wall
« on: May 19, 2016, 10:31:19 am »
You can add a louver in the HVAC vent properties if you want to direct airflow in a specific direction.  I am sure that you could simply create obstructions to resemble your grating, but that is likely not an efficient way to do this. 

What is your intent by not modeling this as an opening? 

Can you make the opening a smaller representation of the total area of the vent minus the area of the grating? 

I think that the velocity directly next to the vent will be slightly different with this approximation.

32
PyroSim / Re: ''New slab'' and ''New obstruction''
« on: May 13, 2016, 08:00:11 pm »
Right and that was the point - they are both treated the same in FDS.  The only difference in PyroSim is that an obstruction will give you Cartesian coordinates to determine the 3D size of the obstruction while a slab will allow you to determine a plane with a thickness.

33
PyroSim / Re: ''New slab'' and ''New obstruction''
« on: May 07, 2016, 08:12:04 pm »
Make one of each and then click the tab at the bottom of the screen which says, "Record View".  This will show you what the PyroSim inputs will look like for FDS.  You should see there that they are both input into FDS as simple obstructions.

34
PyroSim / Re: Rendering an image
« on: April 30, 2016, 08:08:42 pm »
I usually just hit the printscreen button on the keyboard. 

35
PyroSim / Re: hrrpua with sprinkler.
« on: April 25, 2016, 03:30:00 pm »
I agree.  A general assumption that can be made is when sprinklers activate, the HRR stays constant from that point forward - no additional fire growth.

36
PyroSim / Re: about Ramp_Q.
« on: March 21, 2016, 06:16:23 am »
When it stops, it produces an error.  What does the error say?  It should be something like, "numerical instability".

37
PyroSim / Re: about Ramp_Q.
« on: March 17, 2016, 06:02:02 pm »
What is the error you are receiving?  What happens in your model at the time that the error occurs?

38
PyroSim / Re: about Ramp_Q.
« on: March 12, 2016, 08:56:45 am »
Post your entire file.  I don't see anything regarding a mesh.  What is your intent with this model?

39
I can't tell much from the image, but I have a feeling that your very high vent flow from a relatively small vent is going to lead to a numerical stability if you don't ramp it appropriately. 

You should be able to assign a vent flow on a volume basis when creating a vent in pyrosim.  I am not sure what your question is.

40
PyroSim / Re: Extinguishing Coefficient
« on: March 03, 2016, 09:37:23 pm »
When you use a vent burner to control a fire, it is unaffected by any other parameters such as sprinklers.  FDS simply looks at the input HRR from your burner at each time step, and makes the burner output that prescribed HRR.  Sprinklers will not effect the fire size, but will effect other parameters such as fire spread and upper layer gas temperature.

41
PyroSim / Re: Ramp-Up Time
« on: February 26, 2016, 12:09:36 pm »
As we know, fires don't instantly go from nothing to maximum heat release rate.  By setting a ramp, you can gradually control this fire growth rate either by a custom ramp (a function of time vs. HRR output at that time) or t-squared which is a good approximation of how we expect fires to grow in reality.

42
PyroSim / Re: Ramp-Up Time
« on: February 26, 2016, 10:57:30 am »
I am not sure what you are asking.  Can you try to rephrase your question?

43
PyroSim / Re: Long extended run time errors
« on: February 24, 2016, 08:49:20 am »
I saw that response after I posted my response - my apologies. 

Have you considered posting this on the FDS forum?  You can let them know that this is an error received while running the simulation in PyroSim.. but you are unsure if that is the reason for the error.

44
PyroSim / Re: Long extended run time errors
« on: February 24, 2016, 07:07:37 am »
I have had similar problems in the past which I usually attributed to IT doing forced updates on the system.  Do you know if this could possibly be the cause?

45
PyroSim / Re: Case 34789 couldn't find a solution severe (157)
« on: February 19, 2016, 07:16:03 am »
I'm currently running a model or I would try to run yours on my computer.  Why do your meshes cover the exterior of the building?  Cut your mesh off right at the exterior, and put OPEN vents at all the areas where you would expect air flow like a door or window.  Decrease the size of the cells close to the fire to get more accurate results and possibly increase your cell size at areas further away from the fire.

Also, why are all of your objects inside the building modeled as INERT?  This means that these objects will always stay at ambient temperature.  Is this representative of what you are trying to model?

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