Christopher Letchford

Professor & Department Head, Civil and Environmental Engineering Rensselaer Polytechnic Institute

  • Troy NY

Studies wind flows through, and loads upon, the built environment.

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3 min

Rensselaer Experts Available To Discuss Federal Infrastructure Proposal

Federal lawmakers are discussing sweeping infrastructure improvements to transportation, manufacturing, and digital infrastructure, among other projects. Researchers at Rensselaer Polytechnic Institute, the country’s first technological research university, are leaders in improving the sustainability, safety, and performance of transportation systems, energy systems, and wireless networks, among other areas. Experts in civil and environmental engineering, electrical engineering, and mechanical engineering are available to discuss what impact large-scale infrastructure projects could have on a multitude of systems that impact people across the country. Improving Transportation and Freight Systems: José Holguín-Veras, the director of the Center for Infrastructure, Transportation, and the Environment at Rensselaer, and Cara Wang, an associate professor of civil and environmental engineering at Rensselaer, are leading experts on the role of infrastructure on freight systems and transportation, and the environmental impacts of both. Their research focuses on improving transportation and freight systems in order to increase efficiency, reduce traffic congestion and, in turn, reduce vehicle emissions. Professors Holguín-Veras and Wang are available to discuss the ways in which improved roads, bridges, railways, and ports could affect shipping and delivery of goods, congestion in cities, and emissions in the environment. They can also discuss what their research has uncovered that could guide policymakers as new projects are planned. Expanding Broadband: Alhussein Abouzeid, a professor of electrical, computer, and systems engineering, is an expert in networked systems, the smart grid, and the Internet of Things. Some of his research focuses on modeling wireless networks, as well as wireless spectrum and policies to optimize its use. Koushik Kar, also a professor of electrical, computer, and systems engineering, researches communication networks, particularly modeling, analysis, and optimization of the internet and wireless networks. Both researchers are available to discuss the ways in which digital infrastructure can meet future needs. Next-Generation Manufacturing: Part of the President’s infrastructure plan would allocate $300 billion to manufacturing. Next-generation manufacturing is a central area of expertise at Rensselaer, with the Institute’s Manufacturing Innovation Center and the Rensselaer Manufacturing Innovation Learning Lab. Faculty and staff from both state-of-the-art centers, including John Wen, the head of the Department of Electrical, Computer, and Systems Engineering, who is an expert in robotics, are available to discuss the role that Rensselaer research plays in preparing the manufacturing sector for the nation’s current and future needs. Upgrading Electric Grid, Investing in Clean Energy: Joe Chow, Jian Sun, and Luigi Vanfretti, all professors in the Department of Electrical, Computer, and Systems Engineering, hold extensive expertise in modeling, monitoring, and optimizing the electric power grid. Their work will be integral to the development of a cleaner, more resilient power grid, especially as clean energy sources are increasingly integrated. Christopher Letchford, the head of the Department of Civil and Environmental Engineering, is a global expert in wind engineering. His expertise includes wind power modeling, wind climatology, and the impacts of climate change on infrastructure, transportation, and energy production. Each of these experts is available to discuss the importance of upgrading the nation’s electric grid, and the move toward clean and renewable energy. Boosting Electric Vehicle Numbers: Part of President Biden’s plan focuses on increasing the number of electric vehicles on the road. A key component of improved and more cost-efficient electric vehicles is greener, cheaper, more efficient, and longer-lasting batteries. Nikhil Koratkar, an endowed chair professor of mechanical engineering, is a leading expert in energy storage technologies. He has dedicated his research to improving the batteries that society already uses, while also developing batteries of the future. He can discuss current battery technology and how advancements in energy storage research could help put more electric vehicles on United States roads. Upgrading Water, Wastewater, and Stormwater Systems: Chip Kilduff, an associate professor of civil and environmental engineering, is an expert in managing water quality and water treatment. He has a particular focus on water treatment approaches like membrane and adsorption-separation processes. Kilduff is available to discuss the importance of upgrading water and wastewater systems and what his research has uncovered about the best methods for managing water quality.

Christopher  LetchfordJosé Holguín-VerasLuigi VanfrettiNikhil Koratkar

1 min

How Can Structures Resist the Damaging Power of Wind During Hurricane Season?

Experts are forecasting an active hurricane season, which has the potential to wreak havoc on communities if they are not adequately prepared. Chris Letchford, an expert in wind engineering and the head of the Department of Civil and Environmental Engineering at Rensselaer Polytechnic Institute, studies how wind and ocean waves interact and how structures withstand wind. Letchford is available to speak about the destructive power of extreme wind and how structures can be built or augmented to mitigate damage.

Christopher  Letchford

Areas of Expertise

Wind Climatology
Wind-Structure Interaction
Environmental Wind Flows
Bluff-Body Aerodynamics
Climate Impacts on Wind Loads

Biography

Christopher Letchford is a global expert in wind engineering and bluff-body aerodynamics. His many research projects have included wind power siting studies, studying how wind and ocean waves interact, and investigating the long-term impacts of climate change on infrastructure, transportation, and energy production. Letchford's research interests have also focused on wind loads on structures, vortex-induced vibrations, wind climatology, and debris flight mechanics.

Letchford joined Rensselaer Polytechnic Institute in 2011 as the head of the Department of Civil and Environmental Engineering. Before that he served as professor and head of the School of Engineering at the University of Tasmania, Australia; a professor, senior associate dean, and associate director of the Wind Science and Engineering Research Center at Texas Tech University; and a faculty member at the University of Queensland in Australia. Before his career in academia, Letchford was a structural engineer.

He is a fellow of the American Society of Civil Engineers, a fellow of the Structural Engineering Institute, a fellow of the Institution of Engineers in Australia, past chair of the American Association for Wind Engineering and the Australasian Wind Engineering Society, a member of ASCE 7 Wind Load subcommittee and ASCE 49 Wind Tunnel Testing committee, and is a Chartered Professional Engineer.

Media

Education

University of Queensland

B.E. (Hons)

Civil Engineering

1980

University of Oxford

DPhil

Wind Engineering

1987

Media Appearances

London Is Changing Its Skyscraper Designs—to Favor Cyclists

Wired  online

2019-09-02

Of the many things to consider when putting up a skyscraper, wind is among the most basic: A building’s not much good if it can’t stand up to a stormy day, or sways so much its occupants might as well be on a boat. But now, structural engineers, architects, and developers in the historic heart of London have to consider how wind affects not just their structures but the pedestrians and cyclists below.

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'Expertise Project' aims to bridge gap between schoolwork, workplace skills

The Times Union  print

2019-02-15

Students trudging through calculus equations, geometry homework or chemistry exams can't be blamed for sometimes wondering — when will I ever need to use this in the real world?

One Capital Region man is tackling that question by hoping to strengthen the link between classroom teachings and the skills students will need in the workplace.

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Hurricane Scientists Aren’t Afraid to Make Eye Contact

The Wall Street Journal  print

2017-09-15

As Floridians fled Hurricane Irma in droves last week, scientists raced toward the storm to clock its wind speed.

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Articles

Energetic scales in a bluff body shear layer

Journal of Fluid Mechanics

Moore, D., Letchford, C., Amitay, M.

2019-07-22

A detailed experimental campaign into separated shear layers stemming from rectangular sections (having aspect ratios of 5 : 1, 3 : 1 and 1 : 1) was carried out at Reynolds numbers range between $1.34\times 10^{4}$ and $1.18\times 10^{5}$ based on the body thickness. Particle image velocimetry was used to locate the highest concentration of fluctuations in the velocity field and subsequent hot-wire measurements at those locations provided adequate spectral resolution to follow the evolution of various instabilities that are active within the separated shear layer. Similar to recent findings by this same group, the shear layer behavior is observed to contain a combination of Reynolds invariant characteristics, including its time-averaged position, while other properties demonstrate clear Reynolds number dependency, including the spatial amplification of turbulent kinetic energy. Additional results here show that the ratio of side lengths of the body is a key parameter in revealing these effects. One reason for this is the level of coupling between modes of instability, which is evaluated using two-point correlation methods. These findings indicate that the separated shear layer on a bluff body is highly nonlinear. A specific set of scales responsible for these unique behaviors is identified and discussed, along with their relationship to other scales in the flow.

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Multivariate simulation for assessing the joint wind and ice hazard in the United States

Journal of Wind Engineering and Industrial Aerodynamics

Sinh, H.N., Lombardo, F., Letchford, C.

2019-01-01

Multi-hazard assessment is receiving increasing attention as often commonly occurring hazards may contain a second or even a third associated hazard. Generally, multi-hazards could be joint hazards (i.e. these hazards occur at the same time), for example, a hurricane usually comes with strong wind, storm surge, and heavy rainfall. They can also be one hazard preceding another, for example, an earthquake generating a tsunami. The jointly occurring hazards in some cases can be more devastating than a single hazard. This paper will describe the assessment of two jointly occurring hazards, wind and ice formation by using an advance numerical simulation. First, multivariate (hourly wind, temperature and precipitation) simulation for many years in the Midwestern US is undertaken. By setting a condition for freezing rain, these parameters were input into a simple ice-accretion model to estimate ice-thickness. A joint hazard curve for wind and ice was then constructed and compared to the existing prescribed treatment of these two hazards in design loading guidelines, such as ASCE 7 in the United States, ISO 12494 (International Standard); and the results from our previous model.

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Transitional Shear Layers on Rectangular Sections: IN-VENTO 2018

Proceedings of the XV Conference of the Italian Association for Wind Engineering

Moore, D., Letchford, C., Amitay, M.

2019-03-13

The present work implements 2D Particle Image Velocimetry measurements in an effort to study the transition process of the separated shear layer on rectangular sections. Inspection of the average and fluctuating vector fields enable quantitative definitions of important length scales such as transition lengths and reattachment lengths. The effect of free stream Reynolds number is examined in detail which, among other points, show clear trends of increasingly rapid transitions lengths over the wind speeds investigated. Additionally, transitional shear layer dynamics are discussed for sections exposed to inclined winds. It is shown that under small angles of attack, relatively large changes in shear layer trajectory result in significant alterations to the global loads felt by the body.

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