Verification Study toward the Strategic Drag Reduction Control of Practical Bluff Boies

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The six research topics we have involved in this project are as follows: (1)Vortex structures and the mechanisms of the aerodynamic drag acting on simplified vehicle models, (2) Mathematical models for the dynamic flow control, (3) Instability of trailing edge vortices, (4) Proposal of the drag reduction control, (5) Effect of the drag reduction control on the on-road conditions, (6) Strategic technology for the drag reduction of real vehicles. First, by imposing dynamic pitching, yawing and lane-change motions on simplified vehicle models, we have revealed how these transient aerodynamic forces are caused by unsteady flow structures around the vehicle models. Applying this knowledge acquired by the simplified models to real sedan-type vehicle shapes, we have clarified the mechanisms of how drag and lift forces changes through the boundary layer and vortex structures on and around the vehicles, then examined possibility of reducing the drag by controlling eddy structures.