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DNS OF TURBULENT FLOW IN AN ELLIPTICAL DUCT

Nikolay V. Nikitin
Institute of Mechanics, Moscow State University, 1 Michurinski prospekt, 119899 Moscow, Russia

Alexander Yakhot
Mechanical and Aerospace Engineering Princeton University; Department of Mechanical Engineering, Ben-Gurion University, Beersheva 84105, Israel

Abstrakt

Direct numerical simulation (DNS) of fully-developed turbulent flow in elliptical ducts is performed. The mean cross-stream secondary flows exhibited by two counter-rotating vortices which are symmetrical about the major ellipse's axis. The mean flow characteristics and turbulence statistics have been obtained. The variation of the statistical quantities such as the Reynolds stresses and turbulence intensities along the minor axis of the elliptical cross-section were found to be similar to plane channel data. The turbulent statistics along the major axis was found to be inhibited by the secondary flow transferring high-momentum fluid from the duct's center towards the wall. The instantaneous velocity fields in the near-wall region revealed structures similar to the "streaks" except in the vicinity of the major axis endpoints where significant reduction of the turbulent activity due to the wall transverse curvature effect was found.