Here’s what is underway … Once completed the clip will be added to the concepts of tracking page.
Concept Illustrated: The Wave Created by the Fast Walk of a Human Foot …
The Idea: Illustrate the movements of the substrate (in this case sand) during formation of a wave from start to finish.
A wave is a fundamental part of a track …
A wave has at least two phases …
The first-phase wave begins at the point where the heel contacts the ground, as the substrate begins responding to the movement of the incoming foot. This phase continues surging forwards just ahead of the descending foot until the ball lands, and the toes have reached the ground. At this point the first-phase wave is complete.
The second-phase wave begins after the foot has fully landed, as the step changes to the push against the ground used to maintain forward motion. This push starts the foot and body moving forwards and the new wave moving rearwards.
After the foot leaves and everything settles down, the final form of the wave remains. This final form is an indicator of how much energy was exerted to keep the body moving and where that push aimed the body.
Following is a link to a clip illustrating measurements of the timing and amounts of pressure created by a human foot during a walking step. This is not a simulation. If you watch it, notice there is an overall increase in pressure from heel towards toe, with the highest pressure generated at the big toe.
https://www.uni-due.de/~qpd800/animwf.html (From the University of Essen, Essen, Germany. Prof. Ewald M. Hennig, Ph.D.)
It is not made clear whether this illustration also includes pressures applied horizontally towards the heel impact area to propel the body forwards.
Stacking Sand 