DES of the Flow Around a Realistic Bus Model Subjected to a Side Wind with 30 Degree Yaw Angle

Paper i proceeding, 2007

Detached-Eddy Simulation (DES) was made for the flow around a 1/10 model of a double-deck bus of the type Scania K112 TL. The bus was subjected to a side wind with 30 degree yaw angle. The Reynolds number of the flow, based on the speed of the side wind and a reference length of sqrt(0.1) m, was 1300000. Detailed flow structures and global quantities such as lift, drag, side force, yaw moment and pressure coefficients were computed. Visualizations of time-averaged and instantaneous flow structures showed that the flow separates on the top and the lee-side faces of the bus. The flow separations on the lee-side face of the bus was found to be unsteady yielding large vortices that shed to the wake flow leaving disturbances on the surface pressure and hence the side force. The flow separation on the top-side face was found to be more stable in the first two third of the bus length. It became unsteady three-dimensional vortex shedding in the last one third of the length of the bus. The flow under the neath of the bus was found to be very complex and was dominated with small vortices shedding from the beams and the wheels of the bus. Good agreement was found between the DES results and the available experimental data.