Dancing Fluid

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Dancing fluid demo

An example of a "Shear thickening fluid".

Ideal for open days

This refers to a post placed on the UCLAN Scitech-l discussion list regarding the above. It is a simple demonstration that can be put together with little effort.
Requirements:

  • Signal Generator
  • Speaker of about 2" diameter and cables
  • Cling film
  • Cornflour
  • Water
  • Elastic bands


Method

Place the cling film over the cone of the speaker and secure with elastic bands. Connect speaker to signal generator set at about 50Hz. Mix Cornflour and water to make a stiff paste (it should pull from the sides of a beaker as stirred). Pour enough cornflour paste onto the cling film so as to make a puddle about 30mm in diameter). Apply a signal and increase signal strength, varying frequency and amplitude to get best resonance in "liquid". Watch as strange things happen...


Notes

The Cornflour is an anti-thixotropic fluid (it gets thicker when stirred). The "shear" in the fluid caused by vibration generates areas of stiff fluid. The puddle will dry out (if left) but can easily be reconstituted.
Research "Faraday waves" for information and "STF armour" if you are interested in applications


External Links


Back to Physics Back to Physics Experiments


--D.B.Ferguson 13:59, 6 November 2007 (GMT)

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