Mohsen Monadi - PhD Candidate, Department of Civil Engineering, Faculty of Engineering, Urmia University,Urmia. Iran
Mirali Mohammadi - Associate professor, Department of Civil Engineering (Hydraulic Structures & River Mechanics),Faculty of Engineering, Urmia University, P O Box ۱۶۵, Urmia ۵۷۵۶۱۱۵۳۱۱, Iran.

To investigate the sedimentation through urban wastewater pipelines a semicircular polyethylene pipeline of diameter ۴۰۰ mm and length ۱۸ m in nearly horizontal orientation with a longitudinal slope of ۰.۰۱ for a discharge capacity of ۱۴.۷ L/s and a volumetric flow concentration of ۳۰% has been used. The solid phase consists of three different particle sizes i.e. ۰.۲۵ mm, ۰.۳۵ mm and ۰.۵۰ mm with the most frequency in the wastewater flow by a density of ۲۶۵۰ kg/m۳. The flow has been simulated by Ansys-Fluent ۲۰۲۰ software. The effect of particle size on volume concentration has been analyzed. The location of maximum deposition is also determined and it has been occurred at x/R=۷۷.۵. Finally, a relationship between the thickness of sedimentation and volume concentration has been proposed.