Section 4: Soil and Water Conservation Engineering
Open Channel Flow
Subtopic: Open Channel Flow
Question Statement:
For the most economical triangular channel section, the included semi-apex angle $\theta/2$ and total apex angle $\theta$ are:
Options:
(A) Semi-apex angle $45^\circ$ and total apex angle $90^\circ$
(B) Semi-apex angle $30^\circ$ and total apex angle $60^\circ$
(C) Semi-apex angle $60^\circ$ and total apex angle $120^\circ$
(D) Total apex angle $45^\circ$
Answer Key:
A
Step-by-Step Solution & Explanation
A right-angled triangular channel ($90^\circ$ total vertex angle, $45^\circ$ side slope) minimizes wetted perimeter for a given area, yielding $R = y / (2\sqrt{2})$.