Tail length influences swimming speed of helical swimmers in granular media

We experimentally investigate the effects of helical tail length on the swimming efficiency of artificial robots in granular matter. Using magnetically driven swimmers, we found that longer tails boost forward velocity, challenging the traditional behavior observed in Newtonian fluids. We reveal the crucial role of head size in these dynamics through a modified Resistive Force Theory model. Our results demonstrate the intricate relationship between head drag and tail morphology, showing long-range effects linked to force chain formation and buckling. This important discovery broadens our understanding of locomotion in granular systems, an area where current theories are limited.