College of Engineering

A master’s thesis was discussed in Department of Dams and Water Resources Engineering / College of Engineering at University of Mosul entitled “The Effect of Entrance Edge Shape of the Diversion Channel on the Bed Morphology at the Junction Region” on Monday, Nov. 01, 2021 submitted by postgraduate student (Ahmed Yahya Abdalhafedh) and Supervised By Dr. Nashwan Kamal Aldeen Mohammed.The thesis included investigation the effect of changing the edge shape of the diversion channel entrance from sharp to round (one edge or both) on the bed morphology and dividing streamlines. The investigation considered five different diversion discharge ratios (Qr) (between 7.5% and 30%) and five different rounded edge diameters (between 6 cm and 18 cm).The results indicated that is a direct relationship between the scour depth to diversion channel bed width (ds/Bb) and (Qr). In general, changing one edge shape or both from sharp to round shows a reduction in scouring when Qr is more than about 20%. In all cases, the largest decrease value of (ds/Bb) was (22%). The entrance shape model with a rounded edge at the upstream recorded outperforming other models in scour reduction. This model shows a reduction in the volume of a scour hole in all cases of Qr and rounded edge diameter with reduction values up to 53.25%. The results also indicate an inverse relationship between (ds/Bb) and the Froude number of the downstream main channel and a direct relationship to the Froude number of the diversion channel. Empirical equations were derived to estimate (ds/Bb) with mean absolute percentage error (MAPE) not exceeded 7.737% for different models.The entrance shape model with rounded edges recorded outperforming other models in a diversion channel sedimentation reduction and in the enhancement of dividing streamlines behavior. However, the entrance shape model with a rounded edge at the downstream recorded outperforming other models in a main channel sedimentation reduction with a reduction value up to 68.3%. The outcomes from this study indicate that is the entrance shape of the diversion channel can be enhanced by modifying the edge or edges of the entrance from sharp to round. This modification contributes to improved bed morphology and uniformity of the dividing streamlines in the junction region.