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Proceedings Paper

Accurate simulation of near-wall turbulence over a compliant tensegrity fabric
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Paper Abstract

This paper presents a new class of compliant surfaces, dubbed tensegrity fabrics, for the problem of reducing the drag induced by near-wall turbulent flows. The substructure upon which this compliant surface is built is based on the "tensegrity" structural paradigm, and is formed as a stable pretensioned network of compressive members ("bars") interconnected by tensile members ("tendons"). Compared with existing compliant surface studies, most of which are based on spring-supported plates or membranes, tensegrity fabrics appear to be better configured to respond to the shear stress fluctuations (in addition to the pressure fluctuations) generated by near-wall turbulence. As a result, once the several parameters affecting the compliance characteristics of the structure are tuned appropriately, the tensegrity fabric might exhibit an improved capacity for dampening the fluctuations of near-wall turbulence, thereby reducing drag. This paper improves our previous work (SPIE Paper 5049-57) and uses a 3D time-dependent coordinate transformation in the flow simulations to account for the motion of the channel walls, and the Cartesian components of the velocity are used as the flow variables. For the spatial discretization, a dealiased pseudospectral scheme is used in the homogeneous directions and a second-order finite difference scheme is used in the wall-normal direction. The code is first validated with several benchmark results that are available in the published literature for flows past both stationary and nonstationary walls. Direct numerical simulations of turbulent flows at Re_tau=150 over the compliant tensegrity fabric are then presented. It is found that, when the stiffness, mass, damping, and orientation of the members of the the unit cell defining the tensegrity fabric are selected appropriately, the near-wall statistics of the turbulence are altered significantly. The flow/structure interface is found to form streamwise-travelling waves reminiscent of those found at air-water interfaces, but traveling at a faster phase velocity. Under certain conditions, the coupled flow/structure system is found to resonate, exhibiting a synchronized, almost sinusoidal interfacial motion with relatively long streamwise correlation.

Paper Details

Date Published: 19 May 2005
PDF: 14 pages
Proc. SPIE 5757, Smart Structures and Materials 2005: Modeling, Signal Processing, and Control, (19 May 2005); doi: 10.1117/12.600582
Show Author Affiliations
Haoxiang Luo, Univ. of California/San Diego (United States)
Thomas R. Bewley, Univ. of California/San Diego (United States)

Published in SPIE Proceedings Vol. 5757:
Smart Structures and Materials 2005: Modeling, Signal Processing, and Control
Ralph C. Smith, Editor(s)

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