how to deifne parameters of Baker-strehlow model in PHAST 6.54?

[safetyuser]

i don't know weathe the parameter of flame expansion and obstacle density is right?
my core question:
1. when we define the obstacle density,is it the obstacle density engulfed by dispersion flammable cloud(between LFL and LFH) or the obstacle density of the area(seprated area by fire walls)

should be the onstruction factor i.e. "the ratio of the volume of the obstructed area occupied by the obstacles and the total volume of the obstructed area itself"

cfr CPR14E "Yellow Book" by TNO and FIRES, EXPLOSIONS, AND TOXIC GAS DISPERSIONS - Effects Calculation and Risk Analysis by CRC press

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