Science and Math For Technology

Friction drag of a moving object is found all along the surface of the object. Molecules of air slow near the surface of the object because of surface friction. Molecules of air slow near the surface of the object because of surface friction. These molecules effect other molecules nearby and form a boundary layer around the surface of the moving object. Two basic patterns of air flow develop in this boundary layer. One is called laminar because of the layered pattern of the molecules that form.

The other pattern is named turbulent because of the uneven air flow. Turbulent air mixes and swirls different layers of air and at the same time increases the boundary layer. This increases the drag as the object travels through the air.

The shape of the rear of an object is another area that should be carefully designed. A straight shape will cause turbulent air and increased drag. The best shape is a gentle reduction in size. This is referred to as boat tailing. Boat tailing is not always possible. The effect of the lack of boat tailing can be easily seen on tractor trailer trucks or minivans. The rears of the vehicles get covered with dirt because of the turbulent air formed there.