Turbulent flow and heat transfer in eccentric annulus

Abstract

A detailed statistical analysis of turbulent flow and heat transfer in eccentric annular duct was performed via direct numerical simulations (DNS) with particular emphasis on the needs of turbulence closure models. A large number of flow characteristics such as components of the Reynolds stress tensor, temperature-velocity correlations and some others were obtained for the first time for such kind of a flow. The results of the paper will serve as a benchmark test case for turbulence modelling, specifically for models intended to be used for flows with partly turbulent regimes.

Turbulent secondary flows in channels with no-slip and shear-free boundaries

“…With the disappearance of the flat section on the lower wall, the region of reduced pressure there also disappears. Accordingly, the flow along the wall in the direction of the vertical line of symmetry disappears as well, and instead of the four-vortex picture of the secondary flow, a two-vortex one arises. Annular eccentric tube (Nikitin 2006 c ; Nikitin, Wang & Chernyshenko 2009), figure 9. The prediction of the shape of the secondary flow in the eccentric annular tube is not so obvious.…”

Boundary layer formulations in orthogonal curvilinear coordinates for flow over wind-generated surface waves

“…The formulation of the Navier-Stokes equations in terms of velocity and vorticity is an interesting alternative form for numerical studies (e.g. Nikitin, Wang & Chernyshenko 2009;Nikitin 2011). Using the summation notation introduced in § 2.1, the momentum equation in an orthogonal curvilinear coordinate system can be expressed in velocity-vorticity formulation as…”

A Comparative Study of Laminar-Turbulent Displacement in an Eccentric Annulus under Imposed Flow Rate and Imposed Pressure Drop Conditions

“…In this and similar flows with slow streamwise variation, the unyielded plug regions also contain significant normal stresses, which means that yielding/removal by secondary flows may be more effective than expected. Secondary flows in eccentric annuli have been studied to some depth [21,22] and show the appearance of two counter-rotating vortices on each side of the plane of symmetry, which transfer high velocity fluid from the wide gap to the narrow gap and return low momentum fluid. In the displacement context, our recent study [23] suggested that these secondary flows do indeed positively affect the displacement of unyielded fluid on the narrow side of strongly eccentric annuli.…”