Numerical evaluation of turbulent flow in a circular conduit along a side weir

Abstract

Side weir is used as a slot in the side wall of the main channel to direct excess water that is above the weir crest. Such structures are used in control of flow level in irrigation, drainage networks and urban sewage disposal systems. Furthermore, circular channels are pretty important because considerable length of sewage disposal and transmission pipeline system is made of circular channels. In this study, changes inflow free surface, turbulence and flow field passing through a circular channel along a side weir are simulated. This means that for modeling the variations in flow free surface and the flow field turbulence, the volume-of-fluid scheme and RNG k-ε turbulence model are used, respectively. In order to validate the accuracy of the numerical model, the flow free surface changes along the side weir, the discharge coefficient of side weir, discharge of side weir, Froude number at upstream of the side weir and specific energy are compared with the experimental measurements. Comparison of simulation results with the experimental measurements shows high accuracy of CFD model. In other words, the root-mean-square error percent and the mean absolute error for flow free surface are, respectively, obtained to be 0.554% and 0.547%. Moreover, average difference between the specific energy at upstream and downstream of the side weir is calculated about 2.1%. The main purpose of this simulation is gaining an understanding of behavior of the passing flow through circular channels with side weir for subcritical flow regime.

Hydrodynamic Behavior Simulation of Flow Performance over Labyrinth Side Weir

“…The water profile can be viewed more clearly along the side weir bank. In which the water level along the side weir demonstrates a sudden fall at In addition, the Volume of fluid scheme (VOF) can be used which is one of the identical methods for solving the applications involving the free surface flow [24,[45][46][47][48]. In this method the volume fraction of every fluid is defined in the whole domain.…”

3d Numerical Simulation of Lateral Overtopping Flows in Curved Channel Using Boundary Fitted Coordinate System

“…Kimura et al 13) applied the 3D RANS model with 2nd and 3rd order non-linear k- models to validate the reproductivity of secondary flows near the outer bank cell using rigid grids. For the 3D simulation of side weir flow, Bagherifar et al 14) predicted the discharge rate, water surface profiles, specific energy, and surface velocities in a straight channel with a circular cross-section using FLOW-3D software. Though their model can predict characteristics of side weir flows with reasonable accuracy, their rectangular grids cannot fit the circular boundary completely, making them use more grids to fit the boundary shape as closely as possible.…”