SPIRAL BUBBLE WAVES

Having mapped out that general types of coiling, we imagine that we had a fairly complete picture but we were wrong. Further experiments, conducted in an exploratory way with no preconceived ideas, revealed remarkable new phenomena.

The first was the appearance of beautiful spiral waves of air bubble in the thin layer of fluid that spreads away from the coiling rope. They form when the successive loops of the rope are slightly offset from one and other, trapping small air pockets. We still do. Do not understand, however, why the spiral had precisely the shape they do or why they only occur for narrow ranges of fluid viscosity, flow rate and fall height.

            We also played with silicone oils of much lower viscosity. These fluids coiled more quickly up to 2000 times per second so we need high speed cameras to record the behavior.