Controllable superposed flow fields based on eccentric cylinder flow

Abstract To investigate the dynamics of droplets in a complex flow, controlling the characteristics of different components is valuable; however, quantitative control methods are currently lacking. In this research, a method was developed to control different components in eccentric cylinder flow, which is considered to be a combination of steady shear flow, oscillatory shear flow, and extensional flow. When the inner and outer cylinders counter-rotate at a critical angular velocity ratio, the extensional rate along a particular streamline can be ignored; thus, eccentric cylinder flow can be simplified to the superposed flow of oscillatory and steady shear flows. The flow field was generated by a custom-built apparatus and validated using particle image velocimetry (PIV). A detailed analysis of the superposed flow and its characteristics was performed. The results reveal the quantitative relationship between these characteristics and both the eccentric and radius ratios, indicating the controllability of the flow field. This superposed flow is promising for investigating the morphological evolution in complex flows during polymer processing.