In this video, we will explain how we teamed up with Bioracer to develop the next step in individual performance clothing for athletes. Golf ball dimples: First, let’s talk about why golf balls have dimples. Euh wait, wasn’t this about athletes? Patience, we’ll get to that in a minute! Golf balls without dimples feature a laminar flow. As the air moves over the surface, a boundary layer of slower moving air grows thicker as it sticks to this surface. As soon as the flow goes beyond the halfway point and needs to contract, it becomes more & more difficult for the flow to stay attached to the surface and eventually separates. This creates a large wake behind the golf ball, which increases drag and slows it down. When you apply dimples to the surface, or another way of increasing the roughness, the boundary layer becomes turbulent. It will mix with the surrounding air and retain more kinetic energy. This energy allows the airflow to stay attached further down the back of the golf ball, reducing the wake created in its path. These dimples may increase the friction drag a little but reduce the pressure drag so much that the golf flies roughly twice as far! So does this mean we should cover every surface with dimples to make it more aerodynamic? Hm, not quite. Increasing surface roughness to create a turbulent boundary layer only makes sense in locations upstream of a location with separation. Otherwise, you’re only increasing the friction drag! Cyclist flow That being said, it’s time to move on to athletes. The flow around a cyclist, for example, is a complex combination of laminar & turbulent flows, that are attached in some regions and separated in others. So the location of where increase the surface roughness is critical. Bioracer, a Belgian company that is well known for its high-tech sports clothing, already offers clothing that features a smooth surface in some areas and a rough one in others. Like increased roughness at the upper arms for example, which are comparable to cylinders in shape and where it pays off to have the flow stay attached further down the back to reduce drag. Individual This is not where it ends though: every athlete is different in terms of body shape and position on the bike. This means that the locations where the flow separates are different as well! To offer a highly individual approach to drag reduction, Bioracer and AirShaper went to the Bike Valley wind tunnel to experiment with roughness increasing materials in different locations. The test specimen of the day was Ismaël Ben-Al-Lal, triathlete, and winner of the Taiwan Iron Man in his age group in 2018 and now prepping for the one in Hawaïi. After computing Ismaël’s aerodynamics using a 3D scanned model we uploaded to the AirShaper platform, we analyzed the results together with Bioracer. We sat down to define suitable locations for increased surface roughness. For example, we didn’t make the entire surface of the upper arms rough, as is done on existing professional jerseys. Instead, we applied rough patches tailored to specific locations on Ismaëls arms & legs and the flow around them. Over a series of wind tunnel tests, we indeed measured drops in aerodynamic resistance and we discussed possible layouts for Ismaëls next personal outfit. This simulation-based aerodynamics approach is our path towards highly individual performance equipment. So that was it for this episode of custom aerodynamics! I hope you liked the video and if you have any questions, just leave them in the comments or get in touch with us directly to discuss your own project. Thanks for watching, see you soon, bye bye! ----------------------------------------------------------------------------------------------------------- Wouter Remmerie Wouter is the Founder of AirShaper, an online, virtual wind tunnel. With this tool and these videos, we want to make aerodynamics accessible to everyone! Interested in more content like this on the field of aerodynamics? Make sure to click that subscribe button, we post new videos every week! Looking for a way to test your Aerodynamics projects without all the hassle and the huge costs coming with it? Check out https://www.AirShaper.com and see how easy it can be!