How Does the Adidas Jabulani Football's Design Affect Air Drag?

[adam7]

Drag On A Sphere... Confused...?

I've been looking at the Adidas Jabulani football from the recent soccer world cup and came across this issue. This ball has many grooves and ridges on it's surface, and also has less seams (as it is constructed from fewer panels), and these seams are shallower than on previous balls.

In my view it seems that the ball is not any lighter as some may say (it is actually on the heavier side of the strictly regulated limits for ball weight), but just moving faster through the air. I understand that this is due to all the dimples and ridges on the surface of the ball (tripping a turbulent boundary layer, less pressure drag), but would this not be negated by fewer seams (i.e. less seams, less places to trip turbulent boundary layer, more pressure drag) ?


If anyone can help me resolve the question at the end of my previous paragraph it would be greatly appreciated. Thanks, Adam

 

[eljose79]

Hello Adam,

Thank you for your question about the drag on a sphere. The Adidas Jabulani football is a great example to study when it comes to understanding the effects of surface texture on drag. Let's break down the different factors that contribute to the drag on a sphere and how they apply to this specific case.

First, let's talk about the dimples and ridges on the surface of the ball. These features create turbulence in the boundary layer, which is the layer of air that flows closest to the surface of the ball. This turbulence helps to reduce the overall drag force acting on the ball. This is known as the "drag crisis" and is why golf balls have dimples on their surface.

Next, let's consider the seams on the ball. You are correct in thinking that fewer seams would result in less turbulence and therefore less drag. However, the effect of the seams on the overall drag force is minimal compared to the dimples and ridges. Additionally, the seams on the Adidas Jabulani ball are designed to be shallower and smoother than previous balls, which helps to reduce their impact on the drag force.

So why does the Adidas Jabulani ball seem to move faster through the air? This is likely due to a combination of factors, including the reduced drag from the dimples and ridges, as well as the overall design and shape of the ball. The Adidas Jabulani was specifically designed to be rounder and smoother than previous balls, which can also contribute to its faster movement through the air.

In summary, the dimples and ridges on the surface of the Adidas Jabulani ball do help to reduce the drag force acting on the ball, and this effect is not negated by the fewer seams on the ball. I hope this helps to resolve your question. Keep exploring and asking questions, that's what science is all about!