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 tractortrailer 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 tractortrailer passes by it, taking into consideration various speeds of the tractortrailer 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 tractortrailer 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 tractortrailer. In addition, a single equation that relates the tractortrailer 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 (Cd): Cd = 1.298 x 10-7 Re.