IJE TRANSACTIONS B: Applications..Vol. 28, No. 11, (November 2015) 1564-1570 Please cite this article as:H. Bonakdari, I. Ebtehaj, H. Azimi, Numerical Analysis of Sediment Transport in Sewer Pipe,International Journal of Engineering (IJE), TRANSACTIONS B: Applications..Vol. 28, No. 11, (November 2015) 1564-1570 International Journal of Engineering Journal Homepage: www.ije.ir Numerical Analysis of Sediment Transport in Sewer Pipe H. Bonakdari * , I. Ebtehaj, H. Azimi Department of Civil Engineering, Razi University, Kermanshah, Iran PAPER INFO Paper history: Received 12 October 2015 Received in revised form 14 November 2015 Accepted 19 November 2015 Keywords: Sediment Transport Non-deposition Numerical Analysis ANSYS-CFX ABSTRACT The efficiency and economical performance of sewer systems is an essential issue in urban drainage. The need for sewers to carry sediment has been recognized for many years. One of the main problems in designing sewerage systems is the sediment deposition. Sedimentation in sewers occurs regularly according to the alternating natural flow. The present study investigates the hydraulic characteristics of flow in channels with a circular cross section with different bed slope and their effects on sediment transport capacity by use of 3D numerical simulation of flow field with ANSYS-CFX software. It studies hydraulic features of the flow passing through a circular channel in a two or three phase conditions. Self-cleansing velocity and volumetric sediment concentration in various Froude numbers were compared by lab outcomes to validate the results of numerical model. Results of numerical simulation indicate a proper adaptation of numerical and experimental models. Longitudinal velocity counters obtained by numerical simulation are compared in two or three phase flows. doi: 10.5829/idosi.ije.2015.28.11b.03 1. INTRODUCTION 1 One of the most important issues to be considered in designing sewer channels is sedimentation of suspended particles. In wastewater channels, sedimentation occurs regularly based on normal flow conditions. Combined sewers, which create the main part of the wastewater conveyance channel, face variety of flow rates in different times of the operation periods. These different ranges and various sediments in many combined sewers results in the repetition of sedimentation, erosion, and transfer in different time durations. Generally, both storm and sanitary flows carry different kinds of particles into the sewer system. If the velocity of passing flow through the sewer channel was not enough or conduit slope was not much to prevent the transfer of suspended particles in flow, they settle down. If the sediments remain long in the wastewater channel, a change in sediments, especially during the absence of precipitation; permanent sedimentation on pipe bottom creates the changes in velocity and shear stress. Therefore, it affects sediment carrying capacity and hydraulic resistance of wastewater channel. * Corresponding Author’s Email: Bonakdari@gmail.com (H. Bonakdari) One of the easiest ways to prevent sediment deposition is using the constant velocity values, but due to the lack consideration of flow conditions and sediment propoerties, using this method, accompanies with no optimal and effective design [1]. Therefore, considering the efficient conditions on sediment transport, sewer system design using the self cleaning concept was performed. Self-cleansing is an important aspect of sanitary sewer design and is desired to minimize the deposition of silt, sediment, and debris. It is generally defined in two ways: First, limit of deposition (Ota and Nalluri [2], Almedeij and Almohsen [3], Ota and Perrusquia [4]) and second is bed deposited (Nalluri et al. [5] Ota and Nalluri [6]). May [7] developed a design method on sediment movement in horizontal or nearly horizontal pipes. Enfinger et al. [8] used the tractive force method to design sewers with self-cleansing conditions based on a critical shear stress. This method can be extended from the design of new sewers to the evaluation of existing sewers under actual conditions. Almedeij [9] suggested a self-cleansing design procedure for rectangular sewers based on the sediment transmit. Ebtehaj and Bonakdari [10] predicted sediment transport in sewer circular conduit by artificial neural network (ANN). Ebtehaj and Bonakdari [11] investigated performance evaluation of adaptive neural