The two images above represent two tools for two very different sports. The image on the left, DragSox®, is a power training tool for swimmers. The image on the right is a suit for the 2014 Olympics speed skaters. The purpose of these tools is diametric—DragSox are designed to slow the swimmer down while the speedskating suit is supposed to make the skater go faster. What they have in common is that they both use mesh. DragSox are entirely made out of mesh; the speedskating suit has a strip of mesh on the back for a “cooling effect.”
In order for us to understand the similarities between DragSox and the speedskating suit depicted on the image above, we have to quickly refresh our memory of fluid dynamics.
Fluid dynamics is an area of physics that studies how fluids behave when they are in motion. Both liquids and gases are considered fluids. The laws that apply to fluids apply to both, liquids and gases.
Now, let’s look at what happens when DragSox are used in the water:
One reason DragSox are so effective at creating drag in the water is due to the properties of mesh. As the swimmer moves through the water, mesh greatly disturbs the laminar movement of water, causes turbulence, and creates an area of low pressure directly behind the swimmer. This area of low pressure essentially sucks the swimmer backward. To overcome this suction, the swimmer has to exert more energy, which is the intended purpose of DragSox.
Since we already know that the physical laws that apply to liquids also apply to gases, we can predict that what happens to the moving swimmer with DragSox in the water will happen to the moving skater with a mesh suit in the air—the mesh on the back of the suit will disturb the laminar movement of air, cause turbulence, and create an area of low pressure which will create drag. In fact, this is exactly what happened during the last winter Olympics in Sochi: “it seemed that the vents on rear of the suit, put in to allow heat to escape, actually allow air to enter - in turn creating drag.”
There were probably other reasons that would explain the slow times of the US Speedskaters in Sochi, but having a mesh strip on the back of the speed suit definitely contributed. All the designers needed was a quick review of fluid dynamics and this could have been prevented. Maybe now they can recycle those speedy speedskating suits and use them for drag-creating training tools!