Pool fire Geometry

[Salah Benkorichi]

Dear colleagues, 

Has any one of you worked on pool fire using FDS through a third party like Blender or other tools which helps in creating a geometry of a pool fire with radius rather than rectangular (as the case in FDS) because FDS can not do this geometry so far. I would be glad to hear some input from you if you have already tried to work on this before, and if there are tools that help. I started recently learning how to use Blender, but I dont know yet how to link it with FDS.

Best regards,

Salah

[Dave McGill]

Hi Salah,

See Circular Vents in section 7.3.2 of the FDS Users Guide. That will show you how to create a circular fire. I don't know if that can be implemented with Blender.

Dave

[Salah Benkorichi]

Hi Dave,

Many thanks, I will try to look at that and come back to you asap.

Kind regards,

Salah

[Salah Benkorichi]

Hi Dave, 

I have checked that section, and it looks like it's circular, but not sure of the shape of it. But I hope there is another way to make it circular.

Best regards

Salah

On Friday, July 8, 2016 at 3:44:41 PM UTC+1, Dave McGill wrote:

[Salah Benkorichi]

This is how it starts.

[Dave McGill]

Salah,

You still have to work within the constraints of the square cells. As the cell size decreases the appearance will be closer and closer to a true circle. However, I don't really see any functional advantage to that.

The difference between the two pictures is that the second picture is showing the vent with the fire beginning in the middle. The first picture shows the fire having spread from the center-point outward to involve the entire vent. You can control that with the spread-rate setting.

Dave

[Salah Benkorichi]

Hi Dave, 

Many thanks, they're the same one, I just want to show the geometry before the fire gets on. You are right about trying to decreasing the size of the cells, I've seen some people doing that too..

Best regards,

Salah

[Elmo Ferreira]

Hi Salah

Maybe the link below can help you so far. It is a pool fire tutorial performed with BlenderFDS.

https://www.youtube.com/watch?v=a-OsF8YisTk

You can ask some questions there and suggest tutorials videos as well.

[Salah Benkorichi]

Hi Elmo,

Many thanks for sharing that video with me, it's very helpful.

Kind regards,

Salah

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[Salah Benkorichi]

Hi Elmo, 

I've left a question there, and I would like to get a feedback on this case. Here is my question

I still have problem when I try to put a circle as a burn instead of the plane. I get an error WARNING: Two VENTs overlap in MESH 1, Cell 50 50 101 . VENT 2 rejected for that cell., so when I run it, it finishes its 5 s but nothing happen as a reaction. Is there any way to correct this? Thanks in advance !

Regards,

Salah

[dr_jfloyd]

You can only assign one boundary condition to a wall cell.  If you have &VENT inputs that overlap XB such that a single wall cell sees more than one &VENT, FDS will use the first definition in the input file and ignore the other.  The warning message is letting you know this has occurred. Check your input file for overlapping VENT inputs for the wall cell indicated and make sure the correct boundary condition is being applied

[Salah Benkorichi]

Hi dr_jfloyd ,

Thanks for your reply. 

You are right. But when I make only one vent, then it would give another ERROR: VENT burn must be a plane. 

Kind regards,

Salah

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[dr_jfloyd]

The XB for a VENT must be a plane.  e.g. X1=X2 or Y1=Y2 or Z1=Z2.  Check your XB inputs for that VENT.

[Elmo Ferreira]

Hi Salah,

As far as you are using BlenderFDS to perform your case,  you can follow some steps to get your "circle" VENT:

- Insert the Cylinder object and define z direction as zero (the cylinder will be a circle - if you insert circle directly maybe it does not work)

- Define the CIRCLE as VENT and use XB as PIXELS instead of FACES.

- Choose your resolution ( maybe 0.01)

- Set your SURF and export your fds file.

Then your should get your "circle" pool fire.

I will post the above steps in the BlenderFDS Youtube channel as well. If it does not work to you I can make a simple tutorial video as soon as possible, just let me kown.

Thanks,

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Elmo Ferreira Jr

Doutorando em Eng. Química  - UNICAMP

Prof. substituto na Universidade Federal do Maranhão

Tel: +55 (98) 3272-9238 / (98) 8229-8038

[Salah Benkorichi]

Hi,

I have received a reply from video maker that Elmo shared with me. And I sucessed in running it.

BlenderFDS

Hi Salah, Thanks for your feedback. As far as you are using BlenderFDS to perform your case,  see the BlenderFDS pool fire video and follow the steps to get your "circle" VENT: 1) In the tutorial we inserted a plane. You should insert a cylinder object and define z direction as zero (the cylinder will be a "CIRCLE" - if you insert circle directly maybe it does not work). 2) Define the created "CIRCLE" as VENT and use XB as PIXELS instead of FACES (here is the point for you). 3) Choose your resolution ( maybe 0.01) 4) Set your SURF and export your fds file. Then you should get your "circle" pool fire.

Many thanks for all your help.

Kind regards,

Salah

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