Design News for Mechanical and Design Engineers

Rose McCallen, an expert in computational fluid dynamics, is a driving force behind the DOE's goal to improve the aerodynamics of heavy trucks.

Present position: Group Leader, Applied Math Group, Center for Applied Scientific Computing, Lawrence Livermore National Laboratory (LLNL), Livermore CA

Degrees: B.S. Math, St. Mary's College; BSME, California State University; MSME and PhD in Mechanical Engineering, University of California, Davis

Area of research: My group at LLNL is leading a consortium made up of universities and national labs in a DOE project to reduce aerodynamic drag of heavy trucks. My research interests include large-eddy simulation of turbulent separating flow, thermal convection of high Rayleigh numbers, and computational modeling.

How you describe your what you do at cocktail parties: I don't go to that many parties.

Why the focus on drag? Actually minimizing aerodynamic drag is just one of the DOE initiatives. But it's important, since it's estimated that 65% of a truck's engine output goes into overcoming drag when traveling at high speeds.

Most recent breakthrough? Through large-eddy simulation and detailed experiments to understand the complex turbulent flow phenomenon of tractor-trailers, we've determined that mounting 2-ft-wide flaps at a 20° angle on the four sides of a trailer's back end are effective in reducing the wake size. This in turn works out to a 15% reduction in drag, which results in a decrease of approximately 7% in fuel use. (To see the plates and their flow field, go to http://en-env.llnl.gov/aerodrag/pdf/ucrlid1518123.pdf.)

What now? We are doing very detailed flow measurements using a method called particle image velocimetry, an imaging technology that allows us to map the entire flow field.

Contact McCallen at mccallen1@llnl.gov or www.llnl.gov/str/May03/McCallen.html. For info on the DOE's research, go to www.trucks.doe.gov.