FLUID MECHANICS QUESTION: Froude's Number

[KAISER91]

Homework Statement

A model spillway has a flow of 100 L/s per m of width. What is the actual flow for the
prototype spillway if the model scale is 1:20?

Homework Equations

qr = qp/qm

The Attempt at a Solution

My attempt;


qm = 100 L/s per m = 0.1 m^3/s per m


Using the length scale ratio: Lr = Lp/Lm = 20/1 = 20




q = Q/b = VA/b = byV/b = yV

therefore, q = yV
hence, qr = yr Vr

yr = Lr which is 20

So how do I get Vr?

 

[KAISER91]

Once I know Vr, I will get qr

Then I can resolve the flow for the prototype using this;

qr = qp/qm

qp = qr x qm


with qm given as 0.1