In this study, the effect of different numbers of baffles is investigated using computational
simulation. Laboratory measurements using different numbers of constant height baffles in
a rectangular primary sedimentation tank are conducted. The velocity fields measured by
an Acoustic Doppler Velocimeter (ADV) are used to verify the results of the computational
model. The effects of the number of baffles arrangement on the hydraulic performance of
primary settling tanks are studied by using two different ways: the parameters of flow pattern
and the Flow Through Curves (FTCs) method. The results of both the experimental and
computational investigations indicate that increasing the number of baffles in suitable
positions provides minimum volume of the recirculation region, dissipates the kinetic
energy, creates a uniform flow field in the tank and finally the hydraulic efficiency of the
sedimentation tank will be improved.