Flow Characteristics Over the Weir with Semi-Circular Crest in Normal and Oblique Plane

Abstract

This paper studies the effect of geometrical characteristics on coefficient of discharge for weirs with semicircular crest in normal and oblique plane as for the purpose of calculating flood discharge passing
over the flood embankments. Experimental program consists of four sizes of weirs used at normal plane and
at deviation from the wall of channel. Four models comprised of crest height (15 cm, 17.5 cm, 20 cm, 22.5
cm,) with radius of circular crest (6 cm, 8 cm, 10.0 cm, 12.0 cm) respectively. Two angle of inclinations (60°,
30°) were used for experimental setup and 90° angle was used for normal weir for each of the weir size.
Results shows that the coefficient of discharge is affected by the geometrical parameters like radius of
circular crest, height of crest and angle of inclination. It was noted that larger the radius of circular crest leads to lower the coefficient of discharge for circular crested weir. As well as greater the crest height leads to lower
the discharge coefficient (Cd). On the other hand the coefficient of discharge for oblique circular crested
weir is higher than normal circular crested weir and increases as the inclination with the wall of channel
increases.