Turbulence Generated Secondary Flows in Ducts of Non-Circular Cross-Section:

The use of algebraic stress models in the prediction of secondary flows in straight ducts of non-circular cross-section is found to be unsatisfactory and to give inconsistent results in the sub-channels within a rod bundle. An algebraic expression is presented which allows the source of axial vorticity to be calculated directly and without iteration. The expression is shown to reproduce secondary velocities in square and triangular ducts, and in a duct consisting of two inter-connected subchannels.