A. Tamayol - School of Mechanical Engineering, Sharif University of Technology, Tehran, ۱۱۳۶۵-۸۶۳۹, Iran
B. Firoozabadi - School of Mechanical Engineering, Sharif University of Technology, Tehran, ۱۱۳۶۵-۸۶۳۹, Iran
G. Ahmadi - Department of Mechanical and aeronautical Engineering, Clarkson University, Potsdam, NY ۱۳۶۹۹, USA

Circulation regions always exist in settling tanks. These regions reduce the tank’s performance and decrease its effective volume. The recirculation zones would result in short-circuiting and high flow mixing problems. The inlet position would also affect the size and location of the recirculation region. Using a proper baffle configuration could substantially increase the performance of the settling tanks. A common procedure for the comparison of the performances of different tanks has been using the Flow Through Curves (FTC) method. FTC, however, neglects tendencies for particles sedimentation. In this work, a new method for evaluation of the settling tanks performance is presented. The new method which is referred to as the particle Tracking Method (PTM) is based on an Eulerian-Lagrangian approach. In this paper, by using FTC and PTM the effects of the inlet position and the baffle configuration on the hydraulic performance of the primary settling tanks were studied and results were compared. Then, shortcomings of the FTC approach were stated. The optimal positioning of the baffles was also determined though a series of computer simulations.

Settling Tanks, Particle Tracking Method (PTM), Flow Through Curve (FTC), Baffle configuration