Self-induced Vibration of a Drop

Self-induced vibration of drops of liquid nitrogen and oxygen placed on a plate with room temperature was observed, and some theoretical studies of this phenomenon are made. The drop became flat owing to the gravity, and its plane shape showed a certain kind of vibration, where its peripheral shape had a standing wave. Moreover, as the drop size decreased through evapolation, the number of waves around the periphery decreased after sudden transitions. Theoretical analysis is made to predict normal mode frequencies for wave numbers 2～6, which agree well with experimental values. A mechanism of self-induction is proposed, which is based on an assumption on vapor flow around the drop.