Numerical Investigations of Transient Wind Shear from Passing Vehicles Near a Road Structure (Part I: Unsteady Reynolds-Averaged Navier-Stokes Simulations)

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Numerical Investigations of Transient Wind Shear from Passing Vehicles Near a Road Structure  (Part I: Unsteady Reynolds-Averaged Navier-Stokes Simulations)


In this research, the authors performed unsteady numerical simulations of a moving Ahmed body under a freeway overpass at different distances from the bridge columns in order to evaluate transient wind shear and the wind load on these columns. Results have shown that when the vehicle is at 0.75W distance from the bridge columns, an unsteady wind speed of up to 24 m/s is observed at the columns with a pressure coefficient difference of 0.9. Here W is the width of the vehicle. These results indicate with an appropriate system for harnessing these wind energy potentials, significant renewable electric power could be generated with zero carbon footprint.


Hamid Rahai, PhD 
Dr. Hamid Rahai is a professor in the Departments of Mechanical and Aerospace Engineering & Biomedical Engineering and Associate Dean for Research and Graduate Studies in the College of Engineering at CSULB. He has taught various classes at the undergraduate and graduate levels in fluid dynamics, thermodynamics, heat transfer, instrumentation, numerical methods, and turbulence, supervised over 65 M.S. theses and projects and PhD dissertations, and published more than 90 technical papers. He has received over $8 million in grants and contracts from the National Science Foundation, Federal Highway Administration, California Energy Commission, California Air Resources Board, Port of Los Angeles, Caltrans, Boeing Company, Southern California Edison, Long Beach Airport, and Long Beach Transit, among others. He was granted a patent for the development of a high-efficiency vertical axis wind turbine (VAWT) and another with Via Verde Company on wind turbine apparatuses. He also has pending patents related to a new diagnostic system for lung diseases using CFD, a new conformal vortex generator tape for reducing wing-tip vortices, and pending patents based on previous MTI-funded research into reducing drag of trailer trucks with rotating cylinders as well as the current study, reducing NOx emissions of gas-powered engines using a humid air system. For the past 26 years, he has been a consultant to local energy and aerospace industries. Dr. Rahai is the recipient of several scholarly and creative activities awards (RSCA), including the 2012 CSULB Impact Accomplishment of the Year in RSCA Award, the 2002–2003 CSULB Distinguished Faculty RSCA Award, and the 2004 Northrop Grumman Excellence in Teaching Award. Dr. Rahai received the Outstanding Engineering Educator Award from the Orange County Engineering Council in California in 2014, and in 2019 he was inducted as a senior member of the National Academy of Inventors (NAI). 

Assma Begum, MS 
Ms. Assma Begum is a graduate student in the joint PhD program between CSULB College of Engineering and the Claremont Graduate University (CGU) and a research assistant at the Center for Energy and Environmental Research & Services (CEERS) in the College of Engineering at California State University, Long Beach. She has been involved in various projects at CEERS related aerodynamics of rotating cylinders and is author and co-author of two technical conference papers. 

January 2021
Vehicle aerodynamics
Wind load
Ahmed body
Wind shear



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