title: Wind-drag estimation in a traffic accident involving a motor scooter and a tractor-trailer.
abstract: This case report describes a noncontact traffic accident involving a motor scooter and a tractor-trailer with a focus on the wind-drag effect. We used load cells to measure the drag force acting on a substantially similar motor scooter when a substantially similar tractor-trailer passes by it, taking into consideration various speeds of the tractor-trailer and distances between the two vehicles. A three-dimensional steady-state flow analysis was also performed by using the CFX program for computational fluid dynamics to examine the streamlines and the pressure distribution around the tractor-trailer at various speeds. From the experiment, for a separation distance of 1.0 m (3.28 ft) and a speed of 90 km/h (55.9 mph), the maximum resultant drag force is 124.5 N (28 lb); this constitutes a degree of force that could abruptly disrupt the stability in maneuvering by an operator who is unaware of the approaching tractor-trailer. In addition, a single equation that relates the tractor-trailer speed to the drag force that acts on the motor scooter was derived on the basis of the Reynolds number (Re) and the wind-drag coefficient (C(d)): C(d) = 1.298 × 10(-7) Re.
authors.affiliation: Department of Physical Engineering, Central District Office of National Institute of Scientific Investigation, Yusung Ku, Daejeon, Korea. color@korea.kr
authors.forename: Chan-Seong
authors.initials: CS
authors.lastname: Park
authors.forename: Seung-Won
authors.initials: SW
authors.lastname: Jeon
authors.forename: Kyu-Jung
authors.initials: KJ
authors.lastname: Lee
authors.forename: Jun-Suk
authors.initials: JS
authors.lastname: Kim
authors.forename: Jae-Geun
authors.initials: JG
authors.lastname: Oh
authors.forename: Jong-Chan
authors.initials: JC
authors.lastname: Park
authors.forename: Hong-Seok
authors.initials: HS
authors.lastname: Lee
authors.forename: Young-Shik
authors.initials: YS
authors.lastname: Choi