Numerical Assessment of Side-Wind Effects on a Bus in Urban Conditions

Abstract

The drag coefficient is usually considered to be a constant value, which allows us to calculate the aerodynamic losses. However, at lower speeds and wind, this value could be distorted. This also applies to buses in urban environments where due to traffic, the speed is relatively low. Since the schedule of the buses is fixed, based on the driving cycle, they travel at a nominal cruising speed. This makes it possible to examine the drag losses in a quasi-steady condition. To find the magnitude of this distortion in losses, a large-eddy simulation method was used with the help of commercially available software. Symmetrical and asymmetrical flows were induced into the digital wind tunnel to assess the distribution of the forces in the cruising direction and examine the flow patterns. It was discovered that the drag forces behave differently due to the low speeds, and calculations should be performed differently compared to high-speed drag evaluations.