Model windbreak nets

[Marcel van Dijk]

Hi all,

I am currently working on modelling gas dispersion in a room (without fire). The gas dispersion is influenced by wind coming through open windows. However, some (not all) of these windows have windbreak nets that block 80-90% of the incoming and outgoing wind. 

Does anyone have an idea if it is possible to include a window that partially blocks wind in FDS?

Thanks in advance!

Best,

Marcel

[dr_jfloyd]

See the discussion on screen drag in the User's Guide. 

[Marcel van Dijk]

Thanks! That helped a lot.

I have been playing a bit with the settings and was wondering about the thickness. From what I gather from the user guide, specifying the thickness in the SURF line affects the thickness per layer. So, the higher the thickness, the fewer layers are required. Intuitively I expected that this would decrease the calculation time. However, when I increase the thickness, the calculation time increases drastically. Do I indeed understand the definition of the thickness correctly, or am I missing something here?

Also, is it an issue if the total thickness of the screen is smaller than the mesh allows? Or should I adjust the mesh such that the thickness of the screen can be captured by it?

Op vrijdag 26 mei 2023 om 18:02:36 UTC+2 schreef dr_jfloyd:

[dr_jfloyd]

The screen drag model is a subgrid model to account for the drag imposed by a window screen. The THICKNESS on SURF should be the actual thickness of the screen. This is a model that is meant for the case where the grid size is much larger than the wire dimension of the screen.