Elusive vortices and patterning bubbles

One of my projects during my residency at Exeter University will be to create an artistic collection of flow visualization, inspired by Milton Van Dyke’s ‘An Album of Fluid Motion’. This week, thanks to my colleagues, I’m closer to understanding how vortices are created with flow around a cylinder – something I wanted to photograph. Depth of water, speed of flow, size of cylinder – all these play a part. I am hoping to make a 3D image which combines the flow at the bottom of the tank with the vortices forming above – still haven’t quite got there, but here are the results so far:

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ink forming patterns at the bottom

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3D patterning: swirling red ink beginning to do the vortex thing

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My work with ink and glycerol travelling within perspex sheets continues to reveal interesting features. I’m always keen to find new sources of tracks and trails, and air bubbles can create streaks like comet tails as they course through the ink. The bubbles may also form small islands around which the ink flows. Here are a couple of examples:

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Comets coming down from the top

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Diversions around bubble islands

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Instability in the sink

Yesterday at the lab I was intrigued to find regular patterning of ink in the most unexpected places – at the sink, whilst cleaning up between experiments using perspex sheets. Luckily my camera was still close by .. here are a couple of examples:

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‘Making tiny waves’ – I think this patterning is called Kelvin-Helmholtz Instability – will check with those who know later on this week!

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Ink dropping from a height and forming regular patterning

These striped patterns seemed remarkably well-defined and stable, like marbling.

Below are some natural textures formed using perspex:

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Treescape

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Ferns and fronds

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A slice of agate

Tracking the ghosts and the slow transformations

I have been using a method of flow visualization where a slow release of ink along the bottom of the channel allows patterns to build up over time. These patterns are remarkably stable, and even remain for several seconds after the source of the patterning, such as the aerofoil shape, is removed. We then have a ghostly reminder of what was there. The pattern then begins to transform as the steady stream of regular ink pulls the curves into long thin lines. I have taken sequences of this process.

This kind of flow visualization buys me some time – it allows me to make ‘time-rich’ images, which I think are the most interesting of all. The example below, called ‘Cosmic impressions’, is a sequence following the path of ink around a shape which is then removed in the second frame; its patterning becomes supplanted by that of the regular stream of ink (third frame). For me, this sequences has echoes of human existence, where a physical, tangible presence may leave an impression after its removal (or death), which gradually becomes transformed by the new patterning brought by the passing of time. We see this process on a larger scale too – cosmic events involving planets or asteroids leave their impression or pattern long after the object itself has passed through, and these patterns are then modified by subsequent sets of patterning … indeed, the appearance of the whole universe can be explained as a sequence of superimposed patterns.

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‘Cosmic impressions I’ Life, colour, tangible presence

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‘Cosmic impressions II’ The ghost of a tangible form

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‘Cosmic impressions III’ Integration with surroundings