Numerical Simulation of the Flow around the Wheel within Wheelhouse

Abstract

Increasing crude oil price and different legislation for vehicle emissions forced the vehicle manufacturer to produce more efficient vehicles. Road vehicle aerodynamics reaches its limits, in designing of optimal upper body shapes. It has been studied that about 25 percent of total aerodynamic resistance originates from the wheels. The effect of rotating wheels exposed to a free-stream, or being partially covered by the car wheelhouse, leads to a dramatic increase in drag and lift coefficients. Numerical simulation of flow around a generic vehicle is used to accurately predict the flow and also to study the development of the flow in time. Two cases are studied, The case of simplified bus shape vehicle and a modified rectangular box shape vehicle. The results of numerical simulations for the vehicle with wheels (bus shape vehicle) were compared with the basic form (modified rectangular box shape vehicle), the obtained result are compared with available experimental data of the flows around the wheels within the wheelhouse. The time-averaged computed flow is examined to reveal both flow structure and new details of flow structures known from previous experiments. The mechanism of formation of the flow structures are explained. A general schematic picture of flow structure is presented. Surface pressures and forces including lift and drag forces are computed and their comparison with experimental results shows reliability of numerical method. This project will try to establish accurate picture of the flow structure around vehicle wheels and also try to provide reasonable explanations for the flow mechanisms. iv