Certain short-stemmed plant species have evolved to utilizing falling rain drops to disperse their seeds. The unique, conical shape of the fruit bodies allows for the conversion of downward momentum to useful, radial momentum. Following a splash, the seeds are expelled at speeds reaching up to five times greater than the impact velocity of the drops, which results in dispersal distances of upwards of one meter (roughly twenty times their stem height).

The cause of this velocity amplification was studied by using conical shape mimics fabricated by a 3D printer. It was observed that the greatest velocity amplification and dispersal distance is caused when the centers of the droplet and splash cup differ by more than 40%. This creates a unique splash which concentrates the momentum of the exiting film in one direction (shown in the two short videos below).

Below is our video submission for the APS Gallery of Fluid Motion. It is a 3-minute video providing a short summary of our work thus far.