[aerohead]

Originally Posted by bondo

In May of 2007, a friend of mine and I made a video of the first Aerolid with tufts of yarn on it. Here is a snapshot of the yarn tufts showing attached air on the sufraces of the Aerolid. I somehow lost the video but at least had kept this snapshot.

The air is attached on the top and sides. At the rear corners it starts to separate. What is really wild is how the air splits on the rear edge of the lid, dead center, and the yarn on the left points left and the yarn on the right points right. I always wondered why this happened.

At the wind tunnel at Allen Park the aero guys spent alot of time with the smoke at the back lip of the Aerolid. They told me the air was separating cleanly off of the roof and that two large counter-rotating vortices, with the one on the left side spinning counter-clockwise and the one on the right side spinning clockwise, created as the air blends off of the sides of the bed into the low pressure air at the rear of the truck, was causing the yarn (or smoke) to go right or left along the rear lip from dead center.

Flow visualization with yarn is easy and fun and can tell us alot about what air does over a surface as most of you know.

Bondo

Looks good to me! Kamm couldn't do better.