Vorticity fluxes and secondary flow: Relevance for turbulence modeling

Vorticity fluxes are analyzed in fully developed turbulent flow through rectangular ducts with a width-to-height ratio of 3, and both straight and semicylindrical side walls, at a centerplane friction Reynolds number Reτ,c≃180. The transport of secondary Reynolds stresses by the secondary flow of Prandtl's second kind is analyzed from a vorticity-flux perspective. This analysis reveals that the in-plane transport of viscous stresses locally counteracts the inhomogeneous distribution of the turbulent shear-stress gradient in the spanwise direction. A relationship is established between the mean and fluctuating transport terms that can be useful to improve turbulence models and their ability to accurately predict the secondary flow. Finally, quadrant analysis is used to evaluate the contribution from the different types of bursting events to the fluctuating transport terms.Received 25 March 2018DOI:https://doi.org/10.1103/PhysRevFluids.3.072602©2018 American Physical SocietyPhysics Subject Headings (PhySH)