Regarding use of D43 and D32 in a test case, BRE_Spray_ .fds.

[Iqbal]

Hi,

I was exploring a test case BRE_Spray_ .fds. In the present version of
this input file, PDPA_D43 (i.e. PDPA_M = 4, PDPA_N = 3) is used.
However, in the earlier version of this file, PDPA_D32 was used. I
know about D43 and D32.

However, I am wondering why D43 is used instead of D32 in the present
test case. In case of determining sprinkler spray particle mean
diameter, should i use D43 or D32?

I would be glad if anyone could give explanation regarding this mater.

Regards

Iqbal

[shostikk]

When overhauling these files some time ago, I took a closer look at
the paper (Murrel et al.) describing the tests, and noticed that the
measured droplet diameters were median values, not Sauter means. I
assume they were volumetric median Dv50.

As the PDPA DEVC in FDS cannot measure the median diameter, I have
chosen to measure D43, which is usually quite close to median value
with the spray distribution shapes used.