Abstract
The secondary flow of the second kind exists in turbulent flow through a straight duct with a non-circular cross section. This secondary flow driven by gradients of the Reynolds stresses makes the flow field complex very much, although its velocity is at most 1 or 2% of the primary flow velocity. Therefore heat transfer in such a duct are also influenced by this secondary flow. In this paper various characteristics on temperature field measured in a square duct with one rib-roughened wall are compared with those in a smooth-walled duct. The distributions of the turbulent Prandtl number obtained from those of the turbulent heat flux are also shown.
