Agitated tank with side entering mixer is commonly used in industrial processes. This study aims to determine the flow pattern and mixing time as function of impeller diameter, impeller rotation speed, and number of impeller blades. The single phase system with water as working fluid inside the stirred tank was modeled using the combination of multiple reference frame (MRF) and k-ϵ turbulence model and calculated using the computational fluid dynamics (CFD) method. The size of stirred tank is 0.4 m and 0.6 m for diameter and height, respectively. The agitated tank was equipped with 45° inclined blade turbine impeller. Four different impeller in diameter and number of blades have been elucidated under various operating condition of impeller rotation speed from l00 rpm until 400 rpm. The simulation results showed that the flow pattern formed is single-loop circulation and vortex, depended on stirred tank configuration and operating conditions. Besides, there were variations in flow patterns change over time for each simulation. This is also affected on mixing performance in term of mixing time to achieve homogenous mixture.