A CFD methodology is used to study the performance of several commercial bicycle wheels over a range of speeds and yaw angles. The wheels studied in this work include the Rolf Sestriere, HED H3 TriSpoke, the Zipp 404, 808 and 1080 deep rim wheels and the Zipp Sub9 disc wheel. Wheels are modeled at speeds of 20mph and 30mph, in contact with the ground, using Reynolds-Averaged Navier Stokes (RANS). Drag, vertical and side (or lift) forces are reported for each wheel. Turning moments are also calculated using the resolved side forces to examine aspects of stability and maneuverability. Drag and side forces over the range of yaw angles studied compare favorably to experimental wind tunnel results. The previously reported unique transition from downward to upward acting vertical force on the Zipp 404 wheel for increasing yaw angles is observed for all deep rim wheels and the disc wheel studied here. Wheels were also modeled at a critical yaw angle of 10 degrees using Delayed Detached Eddy Simulation (DDES) to examine the transient aspects of flows around moving bicycle wheels. It is hoped that a more complete comprehension of these results will lead to improvements in performance, safety and control of bicycle racing wheels used by amateur and professional cyclists and triathletes.

A methodology is presented to apply CFD to study air flow around a rotating bicycle wheel in contact with the ground. The bicycle wheel studied here is an accurate geometrical representation of a commercial racing wheel (Zipp 404). Reynolds-Averaged Navier Stokes (RANS) and Delayed Detached Eddy Simulation (DDES) results are computed at a range of speeds and yaw angles commonly encountered by cyclists. Drag and side (or lift) forces are resolved and compare favorably to experimental results obtained from wind tunnel tests. Vertical forces acting on a rotating bicycle wheel are presented for the first time. A unique transition from downward to upward acting force is observed as the yaw angle is increased. Flow structures are identified and compared for different yaw angles. It is expected that a more complete comprehension of these results will lead to improvements in the performance and handling characteristics of bicycle racing wheels used by professional cyclists and triathletes.

No abstract

No abstract

_____________________________________________________________________________________________This paper represents an entry to the SC|05 Analytics Challenge and describes a new scientific visualization tool designed to allow investigators to more effectively interrogate large unsteady datasets. By utilizing techniques such as data extracts and programmable graphics processing units, this new capability allows users to more freely interrogate time accurate Computational Fluid Dynamics (CFD) solutions in excess of 10 8 grid points. This tool known as the Advanced Technology Viewer (ATViewer) has been incorporated into Intelligent Light's FIELDVIEW 11 product and applied here to interrogate two large unsteady datasets on the order of 60 gigabytes in size. The first is an unsteady Reynolds Averaged Navier-Stokes simulation of a wind turbine operating at a high yawed position. The other is a hybrid Large-Eddy simulation of an elastic helicopter rotor in forward flight.