A General Approach for Flow Optimization and Drag Reduction in Turbulent Pipe Flows

Flow optimization and drag reduction are of great importance in industrial applications. However, most of the structural optimization and drag reduction in pipe flows are based on industrial experience or a large number of experiments, and there is a lack of general theoretical guidance. In the present work, a general approach for flow optimization and drag reduction in turbulent pipe flows is developed based on the irreversibility of flow process and the principle of minimum mechanical energy dissipation. Considering that the effective viscosity coefficient is related to the space coordinates, the field synergy equation of turbulent flow is derived. The reliability and performance of the field synergy principle of turbulent flow as well as the general approach are then evaluated and validated in a turbulent parallel flow conduit, and finally applied to industrial pipe flows. It demonstrates that the present approach is able to optimize flow field for different purposes by adding speed splitter or deflector as an interface at proper locations to alter the interactions between fluid and wall. It is robust and easy to implement, which provides general theoretical guidance for flow optimization and drag reduction in turbulent pipe flows.