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Sibley School of Mechanical and Aerospace Engineering at Cornell University

 

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Zellman Warhaft
Professor
Mechanical and Aerospace Engineering
Research Group Web Page: Fluid Dynamics Research Group
Address:    244 Upson Hall
Cornell University
Ithaca, NY 14853
Phone: 
Fax:    
E-mail:
(607) 255-3898
(607) 255-1222
zw16@cornell.edu

Professor Warhaft is interested in the subject of turbulence, and does experiments in wind tunnels to study its properties. Turbulence in fluids causes enhanced drag over surfaces (vehicles, buildings) and also greatly enhances mixing (a flick of your spoon in a coffee cup allows the cream to mix in seconds. Mixing by molecular diffusion alone would take days). Turbulence causes efficient transport of heat and moisture in the atmosphere and the clearing of pollution. The rate at which reactants are mixed in industrial processes is also determined by the turbulence levels. Using hot-wire anemometers and other techniques, he investigates turbulence mixing as well as fundamental aspects of the turbulence itself. Professor Warhaft is also concerned with the social and environmental aspects of engineering and teaches courses on these topics.

Current Projects
  • Studies of the relationship between turbulence structure and its mixing properties at high Reynolds numbers.
  • Small scale structure of turbulence and its relation to the large scales. Turbulence is a highly non-linear phenomenon, with long range intersection between different length scales. By altering the flow geometry we look at the effects of shear and strain on the small scale motion.
  • Using high speed cameras and laser light sheets we track small water droplets (order of 10 micron) in a highly turbulent flow. The Lagrangian trajectories will tell us how the drops move in relation to each other. Our objective is to understand cloud formation. The fast rate at which rain drops are formed still remains a mystery and the fluid dynamics plays a complex role.
Selected Publications

Z. Warhaft
"Passive scalars in turbulent flows," Annual Review of Fluid Mechanics, 32 203-240, 2000.

Z. Warhaft and X. Shen
"On the higher order mixed structure functions in laboratory shear flows," Phys. of Fluids, 14(7) 2002.

Z. Warhaft
"Turbulence in Nature and in the Laboratory," Proceedings of the National Academy of Science, 99(1) 2481-2486, 2002.

X. Shen and Z. Warhaft
"Longitudinal and transverse structure functions in sheared and unsheared wind-tunnel turbulence," Phys. of Fluids, 14(1) 370-381, 2002.

X. Shen and Z. Warhaft
"The anisotropy of the small scale structure in high Reynolds number     (Re ~ 1000) turbulent shear flow," Phys. of Fluids, 12 (11) 2976-2989, 2000.

A. Gylfason, S. Ayyalasomayajula and Z. Warhaft
"Intermittency, pressure and acceleration statistics from hot-wire measurements in wind-tunnel turbulence," J. Fluid Mech, 501 213-229, 2005.

A. Gylfason and Z. Warhaft
"On higher order passive structure functions in grid turbulence," Phys. of Fluids , 16(11) 4012-4029, 2004.

Biography

After completing his undergraduate education, Prof. Warhaft was an engineer at the Radio Progagation Research Division, Australian Post Office Research Laboratories, in Melbourne, where he conducted experiments on the effect of the weather on microwave radio propagation. Then, for six years through 1975, he was a research scientist at The Radio and Space Research Station, Science Research Council, United Kingdom (now The Appleton-Rutherford Laboratory). After earning his doctorate, he became a senior project associate for the Department of Aerospace Engineering at The Pennsylvania State University, where he also worked with the Meteorology Department. Since 1977 he has been at Cornell University.

Education
Ph.D. 1975  -  University College, London
B.E. 1967  -  Melbourne, Australia