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  • [October 11, 2017]

    Coherent Structure of Turbulent Boundary Layers: Part I: Observations and Mechanisms

  • Speaker:
    Charles R. Smith
    Wednesday, October 11, 2017
    Room 210, COE building No.1
    Cunbiao Lee
  • Abstract
  • A variety of flow structures have been suggested as important in the development and regeneration of turbulent boundary layers.  The majority of these suggested flow structures are associated with some form of vortex structure, from streamwise and transverse vortices to multiple hairpin-like vortices.  However, most of the flow structures and their hypothesized behavior are based on inferences from measurements or simulations of fully-turbulent flows, often revolving around a discussion of kinematics, but with little dynamic support.  
    The two presentations will be given on the present topic.  The first (Part I, today’s talk) will review some of the past studies of turbulent boundary layers, with particular attention to those studies attempting to visualize the flow structure of the boundary layer, including the author’s own studies using hydrogen bubble visualization in water. Comparisons will be made, including with the patterns created by synthesized hairpin vortex structures created in an otherwise laminar environment.

  • Biography
  • Dr. Smith is an Emeritus Professor and past Chairman of Mechanical Engineering at Lehigh University, Bethlehem, Pennsylvania, and is internationally  recognized for his research in fluid mechanics, particularly the areas of turbulent flow, unsteady flow effects, flow visualization techniques, fluid dynamic image processing,  flow mixing and conditioning, and fluid dynamic use of "smart" materials.  
    Dr. Smith received his Ph.D. from Stanford University, Palo Alto, California, in 1971.  His doctoral work, under the direction of Professor Stephen J. Kline, was completed under a National Science Foundation traineeship, and dealt with unsteady, separated flow behavior in diffusers.
    From 1971 to 1978 Dr. Smith was Assistant and Associate Professor of Mechanical Engineering at Purdue University, W. Lafayette, Indiana.  During his seven years at Purdue he was a staff member at the Purdue University Thermal Sciences and Propulsion Center, and designed and developed a graduate fluid dynamics research laboratory at the Center.        At Lehigh, Dr. Smith developed an internationally recognized facility for the study of the structure of turbulent boundary layers.  His research is directed toward unraveling and explaining the complexities of turbulent flows such that more efficient methods for the prediction and control of turbulence may be developed.  In addition, Dr. Smith researched the use of computer-aided image processing and assessment techniques in fluid mechanics and heat transfer using video image acquisition and digital analysis.  Dr. Smith has also done extensive work on flow conditioning and mixing, which led to the development of the first passive flow conditioning and mixing device based on concepts of coherent turbulent flow structure.  
    In addition to his research activities at Lehigh, Dr. Smith taught graduate and undergraduate courses and is the past Chair of the department.  He also served as the Director of the Industry Liaison Consulting Program in the Lehigh Institute of Thermal Engineering and Sciences, is past Chairman of the Division of Thermosciences (10 faculty members) within the Department of Mechanical Engineering and Mechanics, and served on and chaired numerous university committees.  Dr. Smith also organized and coordinated an International Workshop on Coherent Structure of Turbulent Boundary Layers held at Lehigh University in 1978.  In 1974 he received a NASA-ASEE Faculty Fellowship at NASA-Ames Research Center, Sunnyvale, California.  He served as Papers Chairman and as a Member of the Executive Committee of the ASME Bioengineering Division.  From 1976 to 1979 he served as Associate Editor of the ASME Journal of Biomechanical Engineering; he presently is on the advisory board of Experiments in Fluids.  Dr. Smith is a member of ASME, Pi Tau Sigma, Tau Beta Pi, the American Physical Society, and AIAA.  
    Dr. Smith was also been broadly active in University service activities via committees and Presidential/Provostial/Dean appointments, and prior to retirement served as the University Ombudsperson.
    As an Engineering Consultant, Dr. Smith has worked with over twenty different organizations, providing consultation, design, and trouble shooting in areas such as unsteady flow, mixing, flow metering, industrial heat transfer, cyclone separators, pump effectiveness, energy systems, and mechanical-electrical systems.   In addition, Dr. Smith has provided expert testimony and forensic engineering expertise for thermal accident cases involving fires.  In 1987, Dr. Smith co-founded the VORTAB Corporation, a small start-up company that manufactured and marketed low-loss flow conditioners and fluid mixing devices for pipe flows. His patent for an inline mixer is currently marketed by Chemineer-Kenics.  From 1997 to 2006 he was a member of the Board of Directors of Penn Engineering & Manufacturing Company in Danboro, PA, a manufacturer of specialty fasteners.
    Dr. Smith has published an electronic, public domain e-textbook, “Introduction to Graduate Fluid Mechanics,” for entry-level engineering graduate students, and has co-authored an electronic book “Introduction to C++, Excel, MATLAB, and Engineering Computations” with Harvey Stenger, President of SUNY Binghamton, and published by Prentice-Hall. He presently teaches online courses on graduate fluid mechanics, and introduction to engineering.