Vortices form spontaneously only when ambient turbulence and vibration are removed

Evidence

Figure 14.8 (Top) A slice through the cylinder of air reveals a ring vortex street. (Bottom) Vortices form in a water jet emerging from an orifice 1.5 cm in diameter. The vortex rings in the lower picture formed spontaneously, and are beautifully symmetric, but only after much precaution was taken to avoid preexisting turbulence in the water stream and eliminating any building vibrations that could have imprinted their own pattern of vibration on the vortices. — Eric J. Heller, Why You Hear What You Hear- An…, 1325

Categorization

• XREF: Connects to the classic experimental care in Reynolds-number and instability studies, and to the sensitivity of coherent structures to initial conditions.
• SHARE: Worth sending to anyone into experimental fluid dynamics — the fact that building vibrations had to be eliminated to get clean vortex rings is a perfect lab-wisdom tidbit.