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Jim Brasseur
Research Professor, Smead Aerospace
Wednesday, Apr. 9 | 9:35 a.m. | AERO 114

Abstract: I shall discuss two programs of research that have occupied much of my time and the time of two PhD students with whom I am working: Samantha Sheppard and Jarred Kenworthy. Jarred and Samantha’s programs both involve the special turbulence structure created by the impacts of impermeable surfaces on the structure of energy-dominant wall-bounded turbulence eddies. It is in this “surface layer” region that wind turbines operate in the atmospheric boundary layer. I will present key new knowledge extracted from high-fidelity large-eddy simulations by Jarred Kenworthy to understand the nonsteady responses of the wind turbine rotor to the passage of atmospheric surface layer turbulence eddies, with consequent impacts on the wind turbine drivetrain. Jarred’s research shows that strong turbulence-generated nonsteady forcing of the main bearing may underlie the currently excessive levels of main bearing failure.

A key characteristic of surface layer turbulence is the linear growth of integral scale eddy size with distance from the impermeable surface, a key element in what is commonly referred to as “law-of-the-wall” (LOTW) in turbulent boundary layer scaling. I shall describe key elements in a far-reaching fundamental study of surface layer scaling carried out by Samantha Sheppard within a unique experimental program at the �鶹ӰԺ and the Laboratoire de Mécanique des Fluides de Lille in France. We learn that linear scaling of energy-dominant eddy size is generalizable to wider classes of wall-bounded turbulent flows than previously appreciated, extending key LOTW scaling arguments beyond the classical flat-plate turbulent boundary layer for they were developed.

Bio: James Brasseur (Jim) is Research Professor of Aerospace Engineering Sciences at the �鶹ӰԺ. Before, Dr. Brasseur spend 27 years as Professor of Mechanical Engineering, Biomedical Engineering and Mathematics at the Pennsylvania State University, where he retains Emeritus Professor status. Dr. Brasseur is a fluid dynamist with extensive expertise in two general areas of research: (1) turbulence physics and simulation, and modeling within the large-eddy simulation framework, with applications to atmospheric turbulence, wind turbine aerodynamics and turbulent combustion; (2) fluid and solid mechanics integrated within physiology and function of the gastro-intestinal (GI) tract, as well as related issues in drug delivery, including dissolution, transport and absorption in the GI tract and in vitro devices. Dr. Brasseur has served on governing boards of the American Physical Society (APS), the APS Division of Fluid Dynamics, and two medical societies. was president of a medical society and was founding chair of the APS Topical Group on the Physics of Climate. Dr. Brasseur is a member of the Johns Hopkins Society of Scholars and is Fellow of the American Physical Society through the Division of Fluid Dynamics.

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