ENME Webcast Archives

LEADERS IN MECHANICAL ENGINEERING LECTURE SERIES - SPRING 2008

Structural Features of the High Reynolds Number Turbulent Boundary Layer

Lecturer: Joe Klewicki - University of New Hampshire

Original Air Date: Friday, April 18th at 2:00pm

Abstract: The behavior of the turbulent boundary layer at high Reynolds number is of considerable technological interest. The scientific exploration of the high Reynolds number boundary layer is, however, quite difficult owing to a number of substantive technical challenges. These challenges are briefly discussed. The present approach seeks to largely overcome these challenges by exploring the turbulence in the atmospheric surface layer that flows over the salt playa of Utah¡?s west desert. The data presentation in this talk begins with an overview of statistical results from experiments conducted at the Surface Layer Turbulence and Environmental Science Test (SLTEST) Facility. These are compared and contrasted with existing low Reynolds number results, and provide a context for specifically exploring the behavior of the fluctuating wall pressure and its in-plane gradients. All of the measurements were acquired under the condition of near-neutral thermal stability to best mimic the canonical zero pressure gradient boundary layer flow. The Reynolds number (based on surface layer thickness, ƒÔƒz was generally estimated to be between 8 x 105 and 1.2 x 106, and the equivalent sandgrain surface roughness was generally estimated to be in the transitionally rough regime. The measurements presented include velocity and vorticity fluctuation statistics, statistical measures of viscous sublayer structure derived from flow visualizations, and surface pressure and pressure gradient measurements acquired simultaneously from an array of up to ten microphones.