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ISBN : 978-1-56700-478-6

Proceedings of the 24th National and 2nd International ISHMT-ASTFE Heat and Mass Transfer Conference (IHMTC-2017)
2017, December 27-30 , BITS Pilani, Hyderabad, India

DRAG REDUCTION BY INTRODUCTION OF SHEAR-FREE SURFACES IN A TURBULENT CHANNEL FLOW

DOI: 10.1615/IHMTC-2017.3280
pages 2351-2355

Abstract

Drag reduction in internal turbulent flows is feasible by altering the large-scale flow structures by making use of shear-free surfaces (SFSes) (Sood, Cholemari and Srinivasan [1]). Kinematic wall blocking by these surfaces attenuates the wall normal transport of momentum and hence reduces the drag. In this paper the optimization of the process is done with the size, placement and number of the shear-free surfaces as parameters. 3-D RANS simulations using ANSYS CFX 15.0 have been done with Stress Transport (SST) RANS model. It is seen that the location of SFSes in the cross-section is critical; placement in regions where turbulent shear-production is large, greatly reduces the transport. The shear-free surfaces need not be solid; even for a solidity ratio of 0.2 significant drag reduction occurs. The effect of the Reynolds number is also investigated.