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Chaos In A Dripping Faucet. What Is Chaos?. Chaos is the behavior of a dynamic system which exhibits extreme sensitivity to initial conditions. Mathematically, arbitrarily small variations in initial conditions produce differences which vary exponentially over time. Chaos is not randomness.
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What Is Chaos? • Chaos is the behavior of a dynamic system which exhibits extreme sensitivity to initial conditions. • Mathematically, arbitrarily small variations in initial conditions produce differences which vary exponentially over time. • Chaos is not randomness
Some Characteristics Of Chaos Bifurcations
Some Characteristics Of Chaos Strange Attractors Discrete (Poincare Plot) Continuous (Lorentz Attractor)
How A Dripping Faucet Can Lead To Chaos • After each drop, the water at the tip oscillates • These oscillations affect the initial conditions of the next drop • As flow rate increases, these variations in initial conditions become significant and lead to chaos
Supply Tank Valve-Regulated Tank Dropper Laser Photosensor Computer Experimental Set-Up
We experimented with nozzles of four different diameters: • 0.4mm • 0.5mm • 0.75mm • 0.8mm
0.4mm Nozzlebeginning at a slow drip rate • Period-1 attractor: 0.393s • Point of attraction increases over time: probably due to decreased pressure
.4mm Nozzleopened a little more • Appears to have two periods. • However, considering our device measured 700 times per second, or every ~.0014s, there is probably still only a single period.
.4mm Nozzleopened a little more • Has undergone a bifurcation. • The difference in density is due to the different drop sizes in the cycle.
.4mm Nozzleopened a little more • The two periods now have about the same density of observations. • The wide range of times clustered around each period may indicate further bifurcations have occurred.
.4mm Nozzleas open as possible without producing a stream • Appears to have descended into chaos.
Time-Delay Graphs .75mm, 2.3 drops/s .40mm, 8.5 drops/s .80mm, 14 drops/s .40mm, 22.9 drops/s
Conclusions • The time between drops begins as a period-1 attractor at low flow rate. • As the flow rate increases, it becomes a period-2 or period-3 attractor. • Each period bifurcates further, resulting in two branches. • Eventually the system approaches chaos, as evident in the time-delay graphs.
Improving the Experiment • Being able to accurately measure the setting on the valve would let us quantitatively compare the behavior of different nozzles. • A better processor that can handle a high sample rate would allow for more accurate observation of fine-level bifurcations. • Dying the water might reduce the number of unobserved and accidental counts.
Acknowledgments • K.Dreyer and F.R. Hickley Chaos In A Dripping Faucet. 1990. • S.N. Rasband. Chaotic Dynamics of Nonlinear Systems. 1990. • J.R. Taylor Classical Mechanics. 2005.