Kelvin Wave

Making Limonene heavier

In order to increase the specific gravity of limonene and form a strata of it under the water layer, you can mix it with methylene bromide, which has a greater specific gravity. Methylene bromide is a type of organic solvent, and attacks resins, so we couldn't use an acrylic water tank. That was the reason we used a glass water tank for this experiment.

 

Avoiding the effects of surface tension

Waves that occur on the interface use gravity as a restitutive force, and the surface tension that acts on the interface (about 20 dyn/cm) changes the nature of the waves. On the other hand, a high level of surface tension also means that the two liquids do not mix easily, so in order to avoid mixing of the layers when rotating the working fluid, you can't entirely get away from the effects of surface tension. The only option left to minimize the effects of surface tension on the experiment is to ensure a large enough gap between the densities of the two liquids.

 

Getting the color right

We got clear footage of the experiment by fitting a Y2 filter used for photography (a 480 µm shortcut yellow filter).

However, the ways in which color appears to the naked eye, the video camera and in photographs all differ. Looking at the experiment with the naked eyes makes for the best clarity, and although the coloring of the video footage is slightly different to the naked eye, it is still fairly clear. Photography is hardest to get right.

In some cases the limonene and bromide methylene compound fogs up, but if you raise the liquid's temperature, it returns to transparency. The reason for this is unclear. Also if a substance that diffracts light gets between the two polarizing filters, a white spot appears at that point. You also have to be careful of balls of dust, as they stand out too.