Ripples (no nipples)

Washboard road is familiar to drivers of back country roads the world over but also appears in some other surprising places in nature and technology. Just about any time a malleable surface is acted upon by a sideways force, you will get ripples. Washboard road is analogous to the little ripples that form on wind- or water-driven sand at the beach, and to the moguls which develop on ski hills. Motocross bikes and snowmobiles also make ripples. Washboard can also cause tiny bumps on steel railway tracks and even the read head in a hard disk can sometimes hop along the surface of the disk to make a washboard pattern.
A team of physicists from Canada, France and the United Kingdom have recreated this "washboard" phenomenon in the lab with surprising results: ripples appear even when the springy suspension of the car and the rolling shape of the wheel are eliminated. The discovery may smooth the way to designing improved suspension systems that eliminate the bumpy ride.(read more...)