Screen modelling

[Aurelien Thiry]

Dear all

I was trying to model a screen with fds6.1.2 (final aim : screens at the bottom of an electric cabinet).

I ran my own simplified geometries and encountered unexpected results concerning velocities normal to the screen ; running the cases from Issue Tracker led to simular results :

- negative velocities before the screen (kind of reflux)

- negative velocities after the screen (like a low pressure zone just behind the screen, which is not confirmed by Pressure slices files)

These results seems unphysical to me ; any of you would have an advice on this question ?

Regards,

Aurélien Thiry

[dr_jfloyd]

The screen drag correlation is intended for window screen materials.  In the first case you have given the diameter of the wire mesh as 1 cm.  This is far larger than any window screen.  Wire diameters for a typical window screen are under 1 mm.

In the second case your screen only occupies a portion of the domain cross section.  Flow can continue unimpeded around the screen and must slow down at the screen.  What you have defined is in essence flow around a bluff body where you create a re-circulation region immediately downstream.

[THIRY Aurelien PP-LABCENT MPI]

Thank you very much for your assistance, Dr Floyd.

Now my results are as expected.

Regards,

	Aurélien THIRY Ingénieur, Section Ingénierie du feu Pôle des mesures physiques et sciences de l’incendie Laboratoire central de la Préfecture de police mail : aurelie...@interieur.gouv.fr Tél. : 01.55.76.24.39 / Fax. : 01.55.76.27.18
www.prefecturedepolice.fr

 

-------- Message original --------
Sujet : [INTERNET] [fds-smv] Re: Screen modelling
De : dr_jfloyd <drjf...@gmail.com>
Pour : fds...@googlegroups.com
Date : 3/25/2015 1:57 PM

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