Civil Engineering - Hydraulics - Discussion

The actual measured flow is about 40 per cent less than this, due to contraction similar to a thin-plate orifice.

In terms of an experimental discharge coefficient, the recommended formula is

& 20° < θ < 100° (for heads H > 50 mm.)

The angle of the triangular notch

For maximum discharge, θ should be 90° < 100°

so that, tan θ/2 = 1.

Note:

In a triangular notch, the angle varies between (20° < θ < 100°), so 120° mathematically cannot be the answer.

For triangle notch included angle is 90° and for half-hexagon or trapezoidal, it is 120°.

Answer should be 60°.

@Dileep.

If θ = 120 degree then tan(θ/2) = tan60.

And as we know tan60> tan45, then accordingly answer should be 120.

Thanks for the answer @Dileep.

For triangular notch Q = (8/15)Cd * 2gtan(θ/2)h^(5/2).
For Max discharge θ/2 should be Max.
And θ/2=45.
So θ =90