Dynamic Moving Mesh CFD Study of Semi-truck Passing a Stationary Vehicle with Hood Open

This paper examines the aerodynamic forces on the open hood of a stationary vehicle when another large vehicle, such as an 18-wheel semi-truck, passes by at high speed.

The problem of semi-truck passing a parked car with hood open is solved as a transient two-vehicle aerodynamics problem with a Dynamic Moving Mesh (DMM) capability in commercial CFD software package FLUENT. To assess the computational feasibility, a simplified compact car / semi-truck geometry and CFD meshes are used in the first trial example. At 70 mph semi-truck speed, the CFD results indicate a peak aerodynamic force level of 20N to 30N on the hood of the car, and the direction of the net forces and moments on the hood change multiple times during the passing event. Then another example based on a more realistic semi-truck geometry and a stationary pick-up vehicle with open hood, is used to study the effects of critical dimensional and computational parameters, and, more importantly, to compare with available vehicle test data. The CFD model approach and result are presented, and the computational challenges and future work are discussed.