Engineer devises ways to improve g...( Last summer it was very expensive to...)

Last summer, it was very expensive to fill up a gas tank when the gasoline price hit close to four dollars a gallon. Transportation by road or air consumes fuel, which not only increases our vulnerability to foreign imports but also is a source of greenhouse gas emissions that will impact adverse change in climate and global warming. A mechanical engineer at Washington University in St. Louis is developing techniques that will lessen our monetary pain at the pump by reducing the drag of vehicles. Drag is an aerodynamic force that is the result of resistance a body encounters when it moves in a liquid or gaseous medium (such as air). Reduction in drag means less fuel would be required to overcome the fluid resistance encountered by the moving vehicle.

Working with undergraduate and graduate students, Ramesh K. Agarwal, Ph.D, the William Palm Professor of Engineering at Washington University in St. Louis, has successfully demonstrated that the drag of airplane wings and cars/trucks can be reduced by employing the active flow control (AFC) technology. The idea behind the AFC is to deploy actuators on the surface of these vehicles to modify the flow in a way that the overall resistance is reduced. Using computational fluid dynamics software, Agarwal has found that the actuators modify the flow, which results in drag reduction, which in turn reduces the fuel amount needed.

"The most promising actuators are the so called synthetic jet or oscillatory jet actuators which are embedded in the surface of the body (an airplane wing for example), and essentially perform injection and suction of the fluid from the surface in a periodic manner," said Agarwal. He has demonstrated that the transonic drag of an airplane wing can be reduced by 12 to 15 percent with the incorporation of three-ounce actuators, about 20 to 30 spaced optimally on the surface of the wing.

"We use the genetic algorithms and artificial neural net algorithms to optimize the placem
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