Numerical study of three-dimensional viscous flows with system rotation

A numerical study of three-dimensional viscous subsonic laminar and turbulent flows with system rotation is conducted using a small scalar-potential approximation suggested by Briley and McDonald. The physical approximations are based on identification of primary and secondary flows and lead to a non-elliptic system of governing equations which is solved by a highly economical forward-marching algorithm. In the present study, this approach is extended and applied to compute three-dimensional viscous flow in simple confined rotating geometries. The approximations made were tested in numerical calculations and proved adequate in all of the test cases considered. These test cases include laminar and turbulent flows in rotating straight pipes and ducts, and flow in a rotating 90 degree bend. The creation and evolution of secondary flows due to Coriolis forces associated with system rotation are described, and distortion of the primary flow by the secondary flow is discussed. Modification of the turbulent model for the effects of system rotation on the turbulence structure is also considered. Good agreement is obtained between computed results and available experimental measurements.