Multistable Metafluid based Energy Harvesting and Storage

The thermodynamic properties of fluids play a crucial role in many engineering applications, particularly in the context of energy. Fluids with multistable thermodynamic properties may offer new paths for harvesting and storing energy via transitions between equilibria states. Such artificial multistable fluids can be created using the approach employed in metamaterials, which controls macro‐properties through micro‐structure composition. In this work, the dynamics of such “metafluids” is examined for a configuration of calorically‐perfect compressible gas contained within multistable elastic capsules flowing in a fluid‐filled tube. The velocity‐, pressure‐, and temperature‐fields of multistable compressible metafluids is studied by both analytically and experimentally, focusing on transitions between different equilibria. The dynamics of a single capsule is first examine, which may move or change equilibrium state, due to fluidic forces. The interaction and motion of multiple capsules within a fluid‐filled tube is then studied. It shows that such a system can be used to harvest energy from external temperature variations in either time or space. Thus, fluidic multistability allows specific quanta of energy to be captured and stored indefinitely as well as transported as a fluid, via tubes, at standard atmospheric conditions without the need for thermal isolation. This study proposes a novel approach to energy harvesting, storage, and on‐demand release by integrating compressible gas within a multistable structure. An analytical and experimental investigation is carried out into this “metafluid.” We examine its potential for energy harvesting from temperature fluctuations (such as day and night cycles), store the energy internally, and convert it into mechanical energy when needed.