Partha P. Sarkar (PI), William A. Gallus (Co-PI) and Fred L. Haan, Jr. (Co-PI)

Project Duration: 2002-2005

Sponsor: US National Science Foundation

This project uses a synergistic approach that involves use of field data, numerical simulation, and laboratory simulation to study tornado-induced wind loads on man-made or built structures. The primary objective of this project is to quantify tornado-induced wind loads on typical structures such as low-rise and high-rise buildings, dome-shaped and curved-roof structures, and slender chimneys and towers that comprise the majority of our built environment. In this project, a laboratory tornado simulator at Iowa State University (ISU) is used to realistically produce a variety of tornado-like vortices for testing their loading effects on geometrically-scaled models of built structures. Field measurement data from the University of Oklahoma’s "Doppler on Wheels" studies along with the data generated by numerical simulations of tornado vortex winds at ISU to extrapolate the field data (available for 50 ft and above) to ground level are used to validate the flow field generated by the laboratory tornado simulator. This laboratory simulator uses an innovative mechanism that allows it to produce a translating tornado-like vortex with different Swirl ratios, core diameters and Reynolds numbers suitable for geometrically-scaled model testing.

Partha P. Sarkar (PI)

Project Duration: 2002-2005

Sponsor: US National Science Foundation

This project is for the support of the third joint workshop of Task Committee D (Wind Engineering) of the U.S.-Japan Cooperative Program on Natural Resources (UJNR). This workshop is an ongoing effort of the UJNR Panel on Wind and Seismic Effects to bring together U.S. and Japanese researchers from academic institutions, government laboratories and industry to discuss the state-of-the-art of wind effects on civil engineering structures and develop strategies and collaborative efforts that will benefit both countries. The theme of this workshop is "Reducing Losses from Wind: Collaborative Opportunities for the 21^st Century" and it will be held in Seattle, U.S. on October 2-5, 2002. The purpose of this workshop is to (a) discuss previous collaborative research efforts, (b) continue mutual exchange of technical information on ongoing research, (c) identify collaborative opportunities for the 21^st century and develop strategic planning that will benefit both the countries, (d) identify specific projects for collaborative research, and (e) visit selected sites in the Seattle area related to wind effects on structures.

Partha P. Sarkar (PI) and Fred L. Haan, Jr. (Co-PI)

Project Duration: 2002-2004

Sponsor: US National Science Foundation

This project is to design and build a wind tunnel for aerodynamic and atmospheric boundary layer simulation and testing at Iowa State University. It addresses the need for investment in wind hazard research and education infrastructure by building a facility that represents a new generation of boundary layer wind tunnels designed for more realistic simulation of extreme winds. Extreme wind loads result from extreme weather events (gust fronts, thunderstorms, hurricanes) where non-stationary gusts, transitional flow structures and rapid wind directionality changes might play a significant role. The current state-of-the-art boundary layer wind tunnels cannot simulate such events. The usual assumption in current practice is that atmospheric wind is adequately simulated with stationary mean and turbulence flow properties. Adequate modeling of small-scale turbulence is important and requires a capability to generate high velocities in a relatively large test section. The wind tunnel design in this project incorporates two test sections (2.44 m x 1.83 m and 2.44 m x 2.21 m) with capabilities to generate gusts, active turbulence, and a high velocity of 50 m/s. It will be part of the Wind Simulation and Testing Laboratory that also includes a tornado simulator, a microburst simulator, and an open circuit wind tunnel.

Fred L. Haan, Jr. (PI)

Project Duration: 2003-2008

Sponsor: US National Science Foundation

Research and education activities in this project pursue the mitigation of wind-related natural hazards-the most costly natural hazards faced by the United States. The first objective is to establish a design and testing environment (DTE) in which a diverse collection of participants can learn, design, and test new concepts in wind-resistant design. Second, computational simulation tools will be developed based on discrete vortex methods (DVM). Third, experimental and computational tools will be integrated in such a way that as designs are tested, the models and tools are continuously being validated and improved. From a research standpoint, the DTE will facilitate interaction among researchers, students, and industry for conceiving novel concepts in wind-resistant design. These concepts will be tested using both experimental and computational tools. Research is therefore conducted to search for improved aerodynamic designs and to improve computational techniques. As an educational tool, the DTE will accommodate research and design participants from a wide range of backgrounds working at an appropriate level. All the activity of the DTE-submission of designs to be tested and reporting test results-will be accessible via the Internet. The project's intellectual merit derives from the integrated experimental and computational nature of the simulations and the foundation of discrete vortex methods. The project's broader impacts include new wind resistant design development, new computational tools for design, a database of aerodynamic loads accessible to anyone designing a structure, and a framework that fosters participation by people from a broad range of backgrounds.