Distinction

Make vortices not war

A group of high school students looks at a vortex ring shot from a homemade vortex cannon by two PhD candidates studying unsteady vortex dominated flows. Vortex rings are remarkably stable and their self-propelling properties give the impression that they defy the laws of friction. They are ubiquitous in nature, but often remain invisible like a gust of wind. In this picture, White smoke is used to visualise the vortex ring, which exemplifies how complex flow phenomena can be simply and elegantly visualised.

Vorticious

A vortex ring is created behind a previously immobile cone that is pulled up in water. Vortex rings are ubiquitous in nature and engineering, but mostly they remain invisible. Here, small seeding particles were added to the water and were illuminated by a sheet of light that crossed the cone right in the middle. Images of the particles were recorded with a high speed camera. By playing these images back at reduced speed, we get a unique view of the birth and initial growth of a vortex ring. The movie is two dimensional, but thanks to the particles and diffused light, we can see the three dimensional ring structure form when the cone starts to move. At the edges of the cone, small blobs of particles shed and roll into the vortical structure to make it grow. Every small blob contributes to create the beautiful and powerful large vortex ring. In our research, we strive to create little blobs that contribute to the bigger picture and can help us unfold the fascinating process of vortex formation.