... To develop correlations for prediction of friction factor and Nusselt number. 4 To evaluate the performance of the combined use of transverse ribs and twisted tapes. Figure 1c shows the duct cross section having ribs in opposite walls and twisted tapes centrally placed in the duct cross section...

...Debashis Pramanik; Sujoy K. Saha The heat transfer and the pressure drop characteristics of laminar flow of viscous oil through rectangular and square ducts with internal transverse rib turbulators on two opposite surfaces of the ducts and fitted with twisted tapes have been studied experimentally...