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Messages - Cade_Foster

Pages: [1]
PyroSim / Relaxation factor
« on: October 28, 2017, 09:49:46 am »
Hello everybody,

I want to reduce the relaxation factor to 0.3 in a simulation with pyrosim (the default value is 0.5). I have tried to do it in FDS/Simulation parameters/Misc.

After that, I have written:

Record: MISC
Name: Relaxation factor
Value: 0.3

After that, the simulation doesn't go off. It appears a problem which doesn't allow Pyrosim to run the calculation.

Does anybody know how to reduce the relaxation factor in Pyrosim?

Thabk you very much.

PyroSim / CO concentration in ppm
« on: March 08, 2017, 10:15:36 am »
Hello everybody,

Is it possible to configurate a Pyrosim file so that it provides the Plot3D data files for CO concentration in ppm, instead of mol/mol?

Thank you, cheers.

PyroSim / Friction factor of a wall
« on: March 08, 2017, 07:07:26 am »
Hello everybody,

I have tried to modify the friction factor of a wall in a simulation that I'm carrying out, but I haven't been able to find the place where to do it.

Could anybody help me, please?

Thank you.

PyroSim / Re: Problem with instability
« on: February 19, 2017, 01:38:14 pm »
Hello Jared,

Thank you for your response. According to the FDS User's Guide (section 16.7 Plot3D Static Data Dumps), the plot3d file has a .q extension.

I have tried to visualise the last file with .q extension, unsuccessfully. Which is the file that you are talking about?

Besides, there is a file with a .out extension that outlines the development of the simulation, that I attach to this message. I have seen that there is a huge increase in the maximum velocity error in the last time step before the calculation collapsing, as you will see.

Can I extract useful information from this file?

The fire growth is: t=0 (0 MW), t=5min (60 MW), t=12 min (100 MW), maintaining 100 MW during 1 hour. I also have a supply vent in one of the tunnel's entries.

Thank you for your aid, cheers.

PyroSim / Problem with instability
« on: February 19, 2017, 08:36:18 am »
Hello everybody,

I have tried to carry out a simulation of a 100MW fire in a tunnel, unsuccessfully.

I have found two types of errors by pyrosim:

- First error: numerical instability.
- Second error that says "12.6 MB loaded in 0.11 s - rate: 918.2 Mb/s (overhead 0.01 s). Initializing 3D smoke/hrrpuv blanking array - complete".
- Third error that says "forrt1 severe (157): Program Exception - access violation".

My case is a 700m long tunnel, with a 100MW fire in a train car (in the outside surface). In order to overcome all those errors, I have tried these measures:

- Modify the mesh. I have modified the cells' size, from 0,5x0,5x0,25 to 0,5x0,5x0,5m (x, y, z).
- Before, I had 5 meshes in my pyrosim model. Now, I have unified all of them in a single mesh.
- I have increased the length of the tunnel that I am studying, in order to increase the distance between the fire vent and the entry and exit of the tunnel (having open, exhaust or supply vents close to a fire can create instability).

After all, all my efforts have been in vain, since I haven't been able to make my simulation converge.

I don't know what else to try. Does anyone have any idea that may help me?

I attach two images of the errors that I've found.

Thank you in advance. Cheers.

PyroSim / Re: .xyz and .q files
« on: January 02, 2017, 10:50:43 am »
Thank you very much for your response, Mr Thornton.

Best regards.

PyroSim / .xyz and .q files
« on: December 28, 2016, 06:34:51 am »
Hello everybody,

I have seen that when you run an FDS simulation, it is possible to get files with .xyz and .q extension.

However, when you run the simulation using Pyrosim, you are not given those files.

The question is: is it possible to force Pyrosim to give those files when you run a simulation using it?

Thank you in advance, cheers.

PyroSim / Very low levels of CO concentration
« on: December 16, 2016, 04:08:35 am »
Hello everybody,

I am carrying out a simulation of a fire in a tunnel, and one of my goals is to assess the levels of CO concentration.

The fire definition is the one contained in the attached images.

- Reaction of polyurethane
- Same reaction as default, but reducing the soot yield to 0,1.
- Fire of 15MW, in the external top surface of a train car (20 m2).

The tunnel has the following features:

- Cross - sectional area: 50 m2.
- Height: 7,5m
- Ventilation around 1-2,5 m/s.

As you will see in the pictures that I attach to this email, the levels obtained for CO concentration are always below 700 ppm and they are placed only in the upper part of the tunnel.

These values seem too low to me. Have i made any mistake?

Thank you for your support.

Best regards.

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