Numerical Investigation of the Effect Dimensions of Rectangular Sedimentation Tanks on Its Hydraulic Efficiency Using Flow-3D Software

Abstract

Settling basins are among the essential units built to separate sediment suspended and within the inlet flow particles in water and wastewater treatment plants and irrigation canals. These basins' high efficiency requires proper design, creating a smooth and uniform flow along the basin, and reducing circulation zone as a factor in disrupting the sedimentation process. The present study investigates basin dimensions' effect on its flow pattern. Hence In the current study, the primary rectangular sedimentation basin was modelled three-dimensionally using Flow-3D software. This software takes advantage of two new advanced technique of VOF and FAVOR to model the free surface of the flow and the geometry, respectively. The dimensions of the basin were examined in two scenarios. In the first set-up, the length-to-width ratio was evaluated by increasing length and decreasing width simultaneously and the second part examined the length to depth ratio by decreasing depth and increasing width. In both situations, the volume and location of the inlet and outlet of the basin were constant and unchanged. The outcomes indicate that increasing the ratio of length-to-width and length to depth reduces the volume of the circulation zone significantly. The volume of these zones decreased from 53% for the L/W ratio of one (square basin) to 22% associated with the L/W ratio of eight. Likewise, the volume of these zones decreased by 38% as a result of increasing the L/d ratio from five to ten.