How They Work

Our products are made with porous materials that interact with the wind to reduce its velocity / turbulence intensity.  Porous materials have benefits for flow-control by introducing a fluid permeable medium that modifies the boundary layer, shear layer, and wake characteristics.  In addition, surface interaction with the soft pile fibers reduces wind velocity and the intensity of rotational flows - further reducing air pressure fluctuations.

Our products reduce wind velocity and turbulence intensity.

And move the modified / weaker flow away from the outer ear.

Academic Analogies

Academic research supports the use of porous pile materials to reduce wind turbulence / aerodynamic noise.  As shown in the graphic below (5 m/s wind speed):  "It is remarkable that the near-wall flow is very calm for the case of pile-fabric.  We see that the separated shear layer is thicker and weaker for the pile-fabric compared with the smooth case.  In fact, the streamwise position where the shear fluctuations become maximum is located at about x/d=2.5 for the pile-fabric while it is about x/d=0.4 for the smooth surface." - a)

Flow visualization at 20 mph to verify the above turbulence distribution.

As demonstrated above, pile material significantly modifies downstream flow.

Related Research / References

  • (a- Kudo, T., Nishimura, M., Nishioka, M., Aerodynamic Noise Reducing Techniques by Using Pile-Fabrics., 5th AIAA/CEAS Aeroaoustics Conference., AIAA-Paper. (1999)

  • (a- Nishioka, M., Vorticity Manipulation as an Effective Means for Aerodynamic Noise Reduction., The Eighth Asian Congress for Fluid Mechanics., Shenzhen, China. (1999)

  • Nishioka, M., Aerodynamic Noise Suppression Technique Using Fur., Japan Society of Aeroacoustics and Astroautics, Osaka Prefecture University, Faculty of Engineering Dept. (2000)

  • Nishimura, M., Goto, T., Kobayashi, K., Effect of Several Kinds of Pile-Fabrics on Reducing Aerodynamic Noise., Aeroacoustics Conference Presentation., Monterrey, California. (2005)

  • Massaharu, N., Nishimura, M., Goto, T., Aerodynamic Noise Reduction by Pile Fabrics., Fluid Dynamics Research., Department of Mechanical / Aerospace Engineering, Tottori U.,  Japan. (2010)

Aeroacoustic engineering helps us develop the most effective products.

Cat-Ears / AirStreamz is a leading manufacturer of aero-acoustically designed passive wind noise reduction products.  Tested and recommended by respected publications and professionals, Cat-Ears / AirStreamz are the highest-rated and best-selling products designed for serious cyclists / outdoor sports enthusiasts.  Our products are 100% Satisfaction Guaranteed and Made in the USA.

Aeroacoustic Engineering Research and Product Development | Cedaredge, Colorado

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