Session: 03-09-02 Turbulent Flows (2/3)

Paper Number: 87441

87441 - Surface Roughness and Trip Effects for a Circular Cylinder at Subcritical Reynolds Numbers 

Aerodynamic drag is the major source of resistive force on elite and amateur athletes in sports such as road cycling for steady travel along a level surface. Over bluff bodies, which is how an athlete is typically modelled, passive flow control methods have been effective toward reducing aerodynamic drag. Given the moderate Reynolds numbers experienced by cyclists, surface roughness and boundary layer trips appear particularly relevant for reducing aerodynamic drag by transitioning the local boundary layer at the surfaces to turbulence, resulting in a drag crisis.

Experiments are conducted using a model cylindrical geometry connected to a custom force balance. The test cylinder is within a closed loop wind tunnel that provides a low turbulence freestream. Measurements of the wake produced by the cylinder is made using particle image velocimetry and hotwire anemometry. The model cylinder can be equipped with textile sleeves that are made of materials typical of the speed suits worn by cyclists and surface trips. In the related paper to be presented, the results will include discussion of the effect of surface roughness and boundary layer trips on the drag force, wake parameter and initiation of the drag crisis leading to reduced drag that is typical of higher Reynolds numbers.

Presenting Author: Vidushan Rajavarothayam Department of Mechanical Engineering, York University