Experimental Investigation of Bae E ect on the Flow in a Rectangular Primary Sedimentation Tank


Department of Mechanical Engineering,Sharif University of Technology


In primary sedimentation tanks, short-circuiting enlargement of dead zones and high

ow mixing problems are caused by circulation regions (dead zones), which can reduce the optimal
sedimentation of particles. For proper design of such tanks, the formation of recirculation zones should be
avoided. The provision of a bae as a geometrical modi cation of a tank may in
uence the
ow eld for
better sedimentation. Thus, in this study, velocity measurements were performed by a three-dimensional
Acoustic Doppler Velocimeter (ADV) to investigate bae e ects on the velocity distribution in a primary
rectangular sedimentation tank, quantitatively. E ects of bae positioning were also determined. Mean

ow analysis shows how a bae can alter the hydrodynamics of the
ow eld. It was quantitatively found
that the intermediate bae not only in
uences the
ow eld in its downstream, but also a ects the
pattern in its upstream. It was found that the bae setting and its position relative to the inlet and
outlet in
uences the
ow eld and the development of
ow. Baed
ow may provide better conditions for
sedimentation by in
uencing velocity pro les. However, further detailed experimental study is necessary
to fully capture the bae e ect and obtain further insight into the complex
ow eld in a sedimentation