Jakub Broniszewski, ZA, MEiL, PW, Sprzężona analiza mechaniczno-przepływowa nieustalonego ruchu samochodu - hamowanie

The purpose of this work is to study car dynamics in the presence of unsteady aerodynamics loads. Co-simulation approach was used during research. A unique connection between CFD solver (Fluent), control system (Matlab/Simulink) and multi body dynamics (MSC. Adams) was created.

Car body is a rigid object connected in flexible way with the road. Due to flexibility of tires and suspension system position and inclination of the car body varies in time. Variable position of the car in relation to the road, and especially its inclination, influence aerodynamic forces generated on the car body during fast drive. Aerodynamic forces generation is coupled with different modes of car body motion. Simulation of car dynamics considering aerodynamic forces forms a typical problem of Fluid Structure Interaction (FSI). For solution, different types of solvers had to be used in synchronized way. To allow movement of car body and active aerodynamics surfaces during CFD solution, overset mesh technique was applied. Because velocity was vary in time, the classical reference frame with an observer at rest (stationary model and moving air), was replaced with a moving observer. The problem was further complicated by the presence of movable aerodynamic elements. The main advantages of the proposed methodology over existing solutions are flexibility and robustness. It can be applied to almost any kind of structure without modification. Obtained results show importance of unsteady aerodynamics effects on vehicle behaviour.

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