How to creat a circular geometry?

[Pradeep]

Hi all,

I am struggling to creat a circular geometry in FDS to model big oil
storage tanks involved in tank fire.
Kindly can anyone of you help me.
Is there any option to creat circular geometry in the upcoming
version?

Thank you
Pradeep
Firepro systems

[Roger]

You can make it in a simple way, but the work will be a complex
process,it depends on how you define the cells.The more numbers of
cells you define,the better model you will get.

111
11111
1111111
11111
111
you can define the cells as the above structure. here '1' represent a
single cell.
hope it helps

[mohamed assal]

Hello Pradeep,

Realy with script( FDS code ) i'ts difficult to creat a circular
geometry may be with FDS6 as Dr kevin Mc GRATTEN said in his last
message , it would be nice to use a Pyrosim http://www.thunderheadeng.com/pyrosim/
you will find an example in the website (image; curved 2.psm) about
what you are looking for
I wish you good luck.

[Kevin]

Either buy third party software (like PyroSim) or write a simple
little program to automatically generate text lines like:

&OBST XB=..., SURF_ID='...' /

These small rectangular obstructions should approximate your circular
geometry.

There are many different ways that I have seen people do this. Use
whatever programming or scripting language you like.

[Tony Bova]

As Kevin said, there are a variety of ways to do this, including the
use of spreadsheet software. If you use Matlab, or Octave freeware,
you can use the script titled fds_cylinder_v2.m at
http://sites.google.com/site/bovaprojects/ . When run in Matlab, it
will prompt you for coordinates of a center point, radius, length and
parallel axis around which to build a cylinder. You can also make
hollow cylinders. The script will output a text file, in whatever
directory that you run Matlab, that can be pasted into your FDS input
file. Cylinders, are built by rotating obstructions (and/or holes,
for hollow cylinders) through 180 degrees. I believe this is how
Pyrosim creates (or at least used to create) cylindrical geometries.
~tony

[Paul Hart]

FYI - SFPE offers an Advanced FDS course that covers this topic.

On Feb 25, 7:30 am, Tony Bova <tony271...@earthlink.net> wrote:
> As Kevin said, there are a variety of ways to do this, including the
> use of spreadsheet software. If you use Matlab, or Octave freeware,

> you can use the script titled fds_cylinder_v2.m athttp://sites.google.com/site/bovaprojects/. When run in Matlab, it

> > > Firepro systems- Hide quoted text -
>
> - Show quoted text -

[Brian Cohan]

Here is an excel workbook that I created a while back. A friend had to model a circular atrium and the stairs were rounded as well.

At the top, you have to set up the dimensions of the 'graph paper' to match what you have in your grid. From there, you can click the button that says "Blank Graph Paper" or you can continue down with one of the other three options.

You can create an ellipse (or circle if you set the radii to the same distance) The outer ellipse will create a shape while the inner ellipse will hallow out part of the inner ellipse. To see the default example, just click the "Draw Ellipse" button. Then you can go back and edit the center points, radii, and angle of rotation (if it's an ellipse) to get what you want. I believe the angle is from the positive x axis towards the positive y axis.

The other two option allow you to draw a line as a function of X or a function of Y.

Only edit the orange cells, but when you edit the F(X), F(Y), and F(x,y) cells, make them a function of the respective yellow cells.

How this works is that it will create a sheet and label the axis on the top row and first column with values as prescribed in the top of the setup sheet. It will then loop through each cell in the domain and check if it fits along the line. If it is a point on the line, then it will insert a value equal to what is in the F(x,y) cell. (this allows you to do sloped ceilings)

It will take you to the sheet where the shape is drawn (you may have to zoom out to see the full shape)

On the sheet with shape, there are three options and a button. I do not believe I ever got the X-Shift and Y-Shift functions working, but the Z-thickness should be set to the size of one grid cell by default. The "Get Datapoints" button will then loop through and pull off the X and Y position of a cell that has a value in it (if you remove values, it will ignore the cell) It will take the value in the cell as Z1 and use the Z-thickness to get Z2. It will give you the coordinates for each cell in a new sheet.

On the new sheet you can use the formula
="&OBST  XB="&A2&","&B2&","&C2&","&D2&","&E2&","&F2&" /"
to generate your lines. If need be, you can do some shifting of data in the spread sheet if the object wasn't placed exactly where you need to be.

I hope this explanation is sufficient, but if you need more instruction, you can always email me for more clarification.

--
Brian D. Cohan

[Bryan Klein]

Here is a short YouTube video demonstrating the creation of geometry in the free version of Google SketchUp, then Exporting to DXF or STL file, then importing the file to PyroSim. The video ends with a demonstration of rasterizing the complex geometry into FDS obstructions with a couple of clicks.

http://www.youtube.com/watch?v=PhpzlYuVV5Y

-Bryan

[Tony Bova]

While we're piling on options, don't forget Emanuele Gissi's Blender
interface:
http://www.blenderfds.org/
~t