Evaluation of the Effects of Inlet Conditions on Particle-Laden Flows in Secondary Sedimentation Tanks
Publication: Journal of Environmental Engineering
Volume 146, Issue 3
Abstract
Sedimentation tanks are one of the most important and costly parts of the water treatment process in which particles remaining from previous stages settle down due to the force of gravity. In this research, particle-laden flows in secondary settling tanks are numerically investigated by considering the effect of the free surface using the volume of fluid (VOF) method. Comparison of the results of the current study with available experimental results shows the importance of size distribution and particle diameter deviation from the mean particle size . Moreover, examination of the effects of inlet position as well as inlet Froude number reveals that (1) a decrease in inlet Froude number exerts a positive effect by reducing the volume of the recirculation zone and a negative effect by increasing the maximum velocity. Therefore, an optimum Froude number can be obtained for each geometry that maximizes the tank efficiency. (2) The maximum efficiency occurs when the inlet position is close to the free surface; however, for this case, the recirculation zone is larger than that for cases in which the inlet is in the middle of the tank or close to the bed.
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Data Availability Statement
Some or all data, models, or code generated or used during the study are available from the corresponding author by request.
Available items are listed below:
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Main code (including the solver and numerical setup).
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Data used to generate figures and tables.
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Published In
Journal of Environmental Engineering
Volume 146 • Issue 3 • March 2020
Copyright
©2020 American Society of Civil Engineers.
History
Received: Nov 17, 2018
Accepted: Aug 16, 2019
Published online: Jan 13, 2020
Published in print: Mar 1, 2020
Discussion open until: Jun 13, 2020
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