Spin up and down of vortices

Styrene beads

Styrene beads are the raw material used to make styrene foam. They are a little heavier than water, but if you put beads which contain a foaming agent through boiling water, they expand a little and become lighter. We chose beads which had a specific gravity close to water and used them. This experiment was only a short one, so we did not need a perfectly equal specific gravities.