The viscosity of the working fluid
- The thickness of the Ekman layer is roughly (2 v/f)1/2
(where v is the viscosity coefficient, f is the
Corioli parameter). When you are using normal water
(v=0.01cm2/s) as a working fluid, and the
revolution speed is 10 times per minute (f=2), the
thickness of the Ekman layer is only 1mm. In order to
make the spiral visible, you need to use a fluid with
a viscosity 2 factors higher than water.
- If you use ink as coloration to make the current
visible, after a couple of attempts at the
experiment, color spreads throughout the fluid and it
becomes unusable. If, however, you use a mix of
dissolved sodium hydroxide and phenolphthalein and
mix the water thoroughly after the experiment, the
In this experiment, the colored water's specific
gravity is adjusted to be just a little heavier than
the water with table salt. This is to ensure that the
heads of the colored water (the tip which resembles a
mushroom cloud) do not float up to the surface.
Spouting ink on a rotating table.
- You can't push a syringe on a rotating table by
yourself. In this experiment, it was done by power of
springs which were stretched using an
electromagnet in advance.
- Glycerin has extremely high hygroscopic properties
(it absorbs humidity well). As a result, if you leave
a solution of glycerin out, it absorbs the water in
the air, and its viscosity changes, meaning that
before you start your experiment each time you have
to use tissue paper to absorb and throw out the
surface of the working fluid, and carry out the
experiment as quickly as possible.