Case Studies

simulation@rand.com | RandSIM.com | 888.483.0674 D2H Advanced Technologies: Olympic Success Through Simulation Establishing an Accurate Simulation Model The team started with foundational test cases using smooth and rough cylinders, where published experimental results were available for comparison. By evaluating different cylinder sizes, airflow speeds, turbulence conditions, and simulation models, D2H could determine which approaches most accurately reproduced real-world aerodynamic behavior. The team found that traditional turbulence models, such as k-ω SST, were unable to consistently predict the drag crisis. Accurately capturing this phenomenon required high-resolution computational meshes and the advanced transition turbulence models available in Ansys Fluent. Using these capabilities, D2H successfully reproduced the drag crisis and achieved results that closely matched published experimental data. This provided a validated foundation for exploring more complex skinsuit designs. Simulating the Fine Details of Skinsuit Fabrics With the foundational model established, D2H began investigating the surface features found on actual skinsuit fabrics. Many competitive cycling skinsuits incorporate small ridges or wavy stitched patterns designed to influence airflow. These features, often measuring approximately 1 mm in height, can significantly affect aerodynamic performance. Accurately representing such small details required even finer computational meshes and more sophisticated simulations. As the team evaluated different surface configurations, the simulations revealed valuable insights into how airflow behaves during and after the drag crisis. According to Aidan: "The fascinating thing we found was that after the drag crisis the flow is dominated by vortex shedding. The depth of the crisis is determined by the boundary layers transitioning to turbulent, but after that the shedding behavior changes which affects how much the drag increases after the crisis." These findings helped D2H better understand how specific surface features influence drag and provided direction for further design improvements. Exploring Multi-Layer Fabric Designs Building on these insights, D2H advanced its simulations to investigate more complex, multi-layer fabric configurations. Karman vortex sheet from transient runs with transition modelling of turbulators. Separation is beyond 90 deg on cylinder.

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