Locomotion within granular media like sand, soil and debris that
display both solid and fluid-like behavior is challenging and not well
understood. Here I summarize my modeling efforts to understand the
swimming of the sandfish lizard in sand. High speed x-ray imaging
showed that the 10 cm-long sandfish swims at 2 body-lengths/sec within
sand by propagating an undulatory traveling wave down the body. To
predict the sandfish swimming speed in sand, we developed an empirical
resistive force model by measuring drag force on a small cylinder
oriented at different angles relative to the displacement direction
and summing these forces over the animal movement profile. The model
correctly predicts the animal's wave efficiency (ratio of forward
speed to wave speed) as approximately 0.5. The model also explains the
muscle activation pattern observed on sandfish and solved a
long-standing puzzle of undulatory swimmers. The empirical model
agrees with a more detailed numerical simulation: a multi-segment
model of the sandfish coupled to a multi-particle discrete element
method (DEM) simulation of the granular medium.

个人简介：

丁阳，本科毕业于中国科技大学，2011年在佐治亚理工学院(Georgia Tech)
获得物理博士学位，现于美国南加州大学(University of Southern
California)做博士后。丁阳的研究方向为动物运动和复杂物质。