A numerical study of entrance region in a curved annulus with an inward and outward eccentricity

In this article, developing incompressible fluid flow in a curved annulus with inward and outward eccentricities is studied numerically. To do so, a second order finite difference method based on the projection algorithm is employed to solve the governing equations written in a general bipolar-toroidal coordinate system using a three-dimensional staggered uniform grid. The effects of the governing dimensionless parameters such as the Dean number, Reynolds number, curvature ratio, aspect ratio, and eccentricity on the flow field pattern and friction factor are studied in the entrance region. The numerical results obtained indicate that the outward eccentricity significantly deforms the secondary flows and axial velocity profiles. Furthermore, as the eccentricity increases, the friction factor decreases due to the reduction of secondary flow intensity.