Question

The channel having cross section given below carries a discharge of 10 cumecs. The flow is :

• A. Subcritical
• B. Supercritical
• C. Critical
• D. Can't determine

Answer 1

The correct option is A Subcritical

Area of flow,
A=$(2\times 2.5)+\frac{1}{2}(0.577\times 1)+1\times (2.5-0.577)$
=7.21 $m^2$
Top width, T=3 m
$F_r=\frac{V}{\sqrt{g{L}_c}}=\frac{Q}{A\sqrt{g.\frac{A}{T}}}=\frac{10}{7.21\sqrt{9.81\times \frac{7.21}{3}}}=0.285<1$