Superpropulsion of Droplets and Soft Elastic Solids

Phys Rev Lett. 2017 Sep 8;119(10):108001. doi: 10.1103/PhysRevLett.119.108001. Epub 2017 Sep 8.

Abstract

We investigate the behavior of droplets and soft elastic objects propelled with a catapult. Experiments show that the ejection velocity depends on both the projectile deformation and the catapult acceleration dynamics. With a subtle matching given by a peculiar value of the projectile/catapult frequency ratio, a 250% kinetic energy gain is obtained as compared to the propulsion of a rigid projectile with the same engine. This superpropulsion has strong potentialities: actuation of droplets, sorting of objects according to their elastic properties, and energy saving for propulsion engines.