Titles and Abstracts

Titles and abstracts for “A Day of Locomotion” are listed below:

Swimming on Small Scales
Eric Lauga, UCSD

Microorganisms that are swimming in viscous fluids inhabit a world quite different from the one we are used to experiencing. In this talk, we will discuss some properties and recent results of fluid-based locomotion on very small scales. We will first briefly review the basic properties of swimming without inertia, with an emphasis on the resulting mechanical and physical constraints. We will then present recent experimental and theoretical results on the hydrodynamic attraction of swimming cells by solid surfaces. Finally, we will outline some topics of future research.

Bipedal locomotion
Andy Ruina, Cornell University

The coordination of robotic and natural walking and running is often treated as a complex control problem. In contrast, I will mention some things that can be inferred from simple mechanical analysis. As promoted early on by Tom McMahon and then Tad McGeer, walking gaits can be generated by machines with no control. These machines use relatively little energy and, like many bicycles, can have a measure of self-stability. However, the hypothesis that natural gaits might be largely passive is close in some ways, but not identical to, the stronger hypothesis that natural gaits minimize energy use. The talk will include videos of robots, some heuristic explanations, and few equations.

Bioballistics: An Exercise in Scaling
Steve Vogel, Duke University

Biological projectiles range from a 10-micrometer spore to a 1-meter leaping mammal. Pre-launch accelerations scale inversely with length, with that of the smallest projectile approaching a million times gravity. These projectiles
follow Borelli’s rule, that all jumpers should jump to the same height. Nonetheless, his rationale is wrong on at least two accounts. For one thing, it presumes a muscular engine operating with no energy storage, often far from the case. For another, it ignores drag, critical for small projectiles, which operate in an overwhelmingly drag-dominated rather than gravity-dominated domain and whose optimal trajectories look decidedly unfamiliar. But the rule can be given quite a different and more general basis. And a simple dimensionless index helps us anticipate best launch angles and path lengths, these latter illustrated with a simple computer simulation.

Insect Flight: Aerodynamics, Optimization, and Evolution
Jane Wang, Cornell University

Insects, like birds and fish, locomote via interactions between fluids and flapping wings and fins. Their motion is governed by the Navier-Stokes equation coupled to moving boundaries. In this talk, I will first describe how dragonflies fly: their wing motions and the flows and forces they generate. I will then consider insects in several species and discuss three questions: 1) Is insect flight optimal? 2) How does the efficiency of flapping flight compare to classical fixed-wing flight? 3) How might aerodynamic effects have influenced the evolution of insect flight?

Posting to the eForum

We encourage members of the community to post all locomotion related news here including links to pictures, movies, seminar announcements, etc.

First time users:

1. Go to wordpress.com and click “Sign Up Now!”
2. Select a username and password, fill in email address and select “Just a username, please.” Click next.
3. Send your email address to Peko Hosoi at peko@mit.edu (please put “Locomotion eForum” in the subject line) who will activate your author privileges.
4. Post away!

The above steps are only necessary the first time you login. After your author privileges have been activated, you can simply login using your username to post to the eForum.

Updates

For the latest news on the workshop, click on “A Day of Locomotion” in the menu bar above.