Tag: ink images

The fish and the propeller

Karman vortex street - fully developed
Kármán vortex street, generated by a paddle and captured on paper with dye. The inrolling motion, clockwise at left, counter-clockwise at right, has developed more fully, and the alternating vortexes are clearly discernible. Paddle movement is downwards. From a workshop with Nigel Wells. Archives of Institute of Ecological Technology.

Flip, flap, flip, flap, the tail fin of the trout swishes to and fro, thrusting the fish forward in the still water. Silently it speeds away under the surface. Seemingly without effort it moves, leaving a series of wakes behind. As a contrast, our propeller thrusts water backwards indiscriminately, creating a white foam of turbulent water behind the boat. How can the fish swim so fast and elegant, almost effortlessly? Continue reading The fish and the propeller

Ink droplets falling in water

Umbrella shaped ink droplet
Slowly sinking umbrella shaped ink droplet, like a primitive octopus. Photo(s): Lasse Johansson

Water’s inherent tendency to form patterns can be observed as simple as with ink droplets falling into water (preferably in a container with flat walls). The impact of the droplet creates vaulting toroidal forms, vortexes resembling jellyfish, and finally, when the motion slows down, settles into sinking octopus-like forms.

Studying and looking at the flow patterns can be really captivating. I once tried this experiment with children in kindergarten, who were amazed, and would stand dripping ink into the water for more than half an hour. Continue reading Ink droplets falling in water