A simple model of a turbulent Couette flow, and its application to drag reduction scaling

An accurate model of a turbulent flow in a Couette device, where an effect of secondary flows induced by centripetal forces on a flow field is negligibly small, is developed and validated by experimental data found in open literature. An applicability of a laboratory Couette device for scaling turbulent drag reduction in a pipe flow is analysed. A method of drag reduction scaling, based on using only flow parameters on a solid wall, is suggested and illustrated by calculation examples. A drag reduction effect on the dimensionless torque, applied to the Couette device rotor, is illustrated by a computational example. An approach to scaling the drag reduction effect in hydraulically smooth as well as in rough wall pipes by using experimental data obtained in a Couette device is formulated.