GATE 2016 CE (CE2) – Question 57
A 3 m wide rectangular channel carries 6 m$^3$/s at depth 0.5 m at P. A flat-topped hump is placed downstream. With negligible energy loss and $g=9.81$ m/s$^2$, the maximum hump height that does not change depth at P is ______ m.
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Correct answer: 0.19 to 0.21
Explanation
Unit discharge is6/3=2m²/s. Initial specific energy is0.5+2²/(2·9.81·0.5²)=1.31549m. Critical depth is(4/9.81)^(1/3)=0.74153m and minimum specific energy is1.5yc=1.11230m. Available rise is their difference, **0.2032m**; a higher hump would alter upstream conditions.