Strong Self-Propelled Swing Motion Due to the Growing Instability on Heat Transfer

We report that pendulums having a hot tip immersed in water exhibit a strong self-propelled swing motion. This large swing motion is observed when the temperature of the hot tip becomes that of the nucleate- to film-boiling regime. We propose a model that explains how the strong swing motion occurs owing to the growing asymmetrical instability of heat transfer from the hot tip to the water; i.e., the small swing motion increases the asymmetrical heat transfer and consequently accelerates the swing motion in the liquid. We believe that our findings will contribute significantly to a new class of self-propelled devices and energy conversion systems that convert waste heat into usable energy.ArticleJOURNAL OF THE PHYSICAL SOCIETY OF JAPAN.89(6):064402(2020)journal articl