Curvature Gradient Induced Droplet Motion —John McCarthy (University of Oxford)

Droplets of water (blue) and water-glycerol mixture (red) are propelled along the surface of a brass cone due to pressure gradients induced by the curvature gradient of the cone with larger droplets moving faster. The surface of the cone is lubricated with silicone oil allowing easy motion.

https://downloads.sms.cam.ac.uk/3116271/3116279.mp4