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10.9.14 Denison

TURBULENT DRAG REDUCTION BY SWEPT SURFACE WAVINESS

Marie Denison, NIA Visiting Researcher
October 9, 2014, 10:00 am, NIA, Rm 141
Host: Mujeeb Malik (NASA Langley)

Abstract:
A long-term goal for the next generation of aircrafts is a lowering of their energy requirements and of the emission levels due to their operation. While new aerodynamic design solutions and active flow control are often first considered, passive techniques such as riblets and more generally engineered surface roughness offer the possibility to harvest some of the benefits of turbulent drag reduction at lower infrastructure costs. Swept surface waviness has been suggested as a passive method to create shear stress oscillations that would interfere with the streak formation process leading to a reduction in the viscous drag. The nature of said interactions and their scaling with geometry and Reynolds number have yet to be clarified to assess the applicability of the approach. The presentation will provide an update on the drag reduction effectiveness and turbulent boundary layer mechanisms associated with swept wall waves, based on wind tunnel experiments and Direct Numerical Simulations (DNS) conducted in the Flow Physics and Control branch at the NASA Langley Research Center. The drag of different flat and wavy plate configurations measured in a 7”x11” wind tunnel at a flow velocity up to 45m/s will be reported. The computational analysis, based on a fifth order Weighted Essentially Non-Oscillatory (WENO) code for spatial discretization with third order Total-Variation-Diminishing (TVD) scheme for temporal integration, will compare the effects of wall geometry and span-wise velocity forcing on channel drag at different Reynolds numbers. The talk will conclude with a discussion on the prospects of the swept surface wave technique and an outline of future evaluation plans.

Biography:
Marie Denison is an engineer in computational physics at Texas Instruments, Dallas, TX. Her research interests are focused on flow control, turbulence modeling and high performance computing. Her main contributions relate to the areas of flow receptivity to DBD actuation and power semiconductor modeling. She authored 14 journal papers, 31 conference papers and 33 patents. She received her M.S. Degree in Aerospace Eng. from the University of Texas at Arlington, TX, Ph.D. in Electrical Eng. from the Univ. of Bremen, Germany and M.S. in Applied Physics from the University of Liege, Belgium.

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