Question

A triangular open channel has a vortex angle of ${90}^{\circ }$ and carries flow at a critical depth of 0.3 m. The discharge in the channel is

• A. $0.41m^3/s$
• B. $0.11m^3/s$
• C. $0.31m^3/s$
• D. $0.21m^3/s$

Answer 1

The correct option is B $0.11m^3/s$


For critical flow,
$\frac{Q^{2}T}{g{A}^3}=1So,\frac{Q^2\times 2y}{g{(2\times \frac{1}{2}\times y\times y)}^3}=1$

$(\because Topwidth,T=2y)$

$\Rightarrow Q=\sqrt{\frac{g{y}^5}{2}}=\sqrt{\frac{9.81\times (0.3{)}^5}{2}}$

$\Rightarrow Q=0.11m^3/sec.$