Abstract: Numerical modeling is performed to investigate the mixing effects of flow in pipes consisting of bends with same or different curvatures.The mixing at the transition area between different bends will cause disturb ance in fluid flow. Flow rate (case change of Reynolds number) and curvatures of the bends (case change of Dean number) will take different effects in the development of secondary flow. The results show that a change in Dean number created in varying curvature bends cause significant influence on the flow.