Getting Qideal from Bernouli and continuity

[Sheogoroth]

So, I found a paper relating to a lab report that I've been working on that says that I can get
Qideal=(pi*d^2)/4) √((2ΔP/(ρ(1-D/D')^4 ))
From Bernouli which my book has as:
P₁/ρ₁+1/2v₁^2+gh₁=P₂/ρ₂+(1/2)v2^2+gh₂

and Continuity which my book has as:
ρ1A1V1 = ρ2A2V2

I'm able to get kind of in that direction applying this,
ΔP = -ρgΔh

And the area portion makes sense logically

But I'm wondering what I'm missing.
Thanks!

 

[Chestermiller]

The OP seems to be citing a relationship for calculating the volumetric flow rate across a resistance in the flow, such as an orifice plate based on the pressure difference across the resistance.