Multiphase flow physics of room temperature liquid metals and its applications

Multiphase flow existing everywhere in the motion evolution of nature, industrial processes, and daily life, has been an interdisciplinary cutting-edge frontier covering rather diverse disciplines. Traditional multiphase flow of high melting metals typically involves gas/vapor-liquid two-phase fluidics which usually requests intense energy processes and therefore limits their applications to a large extent. From an alternative, the newly emerging room-temperature liquid metals (RTLMs) with fascinating metallic fluidic properties and multifunctional behaviors, not only well resolves the existing challenges facing conventional technologies, but also opens up a series of new scientific and engineering subjects. Especially, the conceptual introduction of multiphase composites endows liquid metal with many unconventional fluidic capabilities. To further push forward the advancement of this new area, the present article is dedicated to systematically outlining the scientific category of RTLMs multiphase flow physics and interpreting its fundamental and practical issues. The vision is to provide insights into promising developmental directions of RTLMs multiphase flow and thus facilitate synergetic research and progress among different disciplines. First, the traditional metal multiphase flow was briefly introduced. Then, we summarized the physics of RTLMs multiphase flow, the common types of liquid metals, the basic physical and chemical properties of their multiphase flow and governing equations, etc. Following that, various typical driving modalities and manipulation methods of RTLMs were illustrated. Finally, important implementations of RTLMs multiphase flow into thermal management, energy harvesting, catalysis, soft machines, biomedicine, and printed electronics were discussed. Overall, the multiphase flow physics of RTLMs is currently still in its incubation stage and there exist tremendous opportunities and challenges which are worth further pursuing in the coming time.