Acceleration is the key to drag reduction in turbulent flow Article Swipe

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Drag Reynolds number Turbulence Mechanics Drag coefficient Acceleration Physics Flow (mathematics) Aerodynamic drag Pipe flow Parasitic drag Drag divergence Mach number Range (aeronautics) Reduction (mathematics) Oscillation (cell signaling) Classical mechanics Aerospace engineering Mathematics Engineering Geometry Biology Genetics

Liuyang Ding , Lena Sabidussi , Brian C. Holloway , Marcus Hultmark , Alexander J. Smits ·

YOU? · · 2024 · Open Access · · DOI: https://doi.org/10.1073/pnas.2403968121 · OA: W4403511667

A turbulent pipe flow experiment was conducted where the surface of the pipe was oscillated azimuthally over a wide range of frequencies, amplitudes, and Reynolds numbers. The drag was reduced by as much as 35%. Past work has suggested that the drag reduction scales with the velocity amplitude of the motion, its period, and/or the Reynolds number. Here, we find that the key parameter is the acceleration, which greatly simplifies the complexity of the phenomenon. This result is shown to apply to channel flows with spanwise surface oscillation as well. This insight opens potential avenues for reducing fuel consumption by large vehicles and for reducing energy costs in large piping systems.