Smoke rings. This is a poloidal (rotating) vortex flow that is stable for considerable distances in still air. The rotating flow is maintained by the viscous friction between the moving ring and the stationary air outside it | |
Lizenzart: | Lizenzfrei |
Credit: | Science Photo Library |
Modell-Rechte: | nicht erforderlich |
Eigentums-Rechte: | nicht erforderlich |
Restrictions: | - |