Bubble Nucleation and Growth in a Force-Driven Flowing Liquid Film Under Controlled Pressure by Molecular Dynamics Simulation.

Bubble nucleation in flowing liquid films is a common interfacial phenomenon affecting the heat and mass transfer at the solid-liquid interfaces in many thermal and functional material production processes, yet realizing its molecular-scale mechanisms under coupled flow, pressure, and heating conditions is important. In this study, molecular dynamics simulations are performed to investigate the bubble nucleation and growth in a liquid argon film on a heated platinum substrate under controlled pressure, with liquid flow driven by an applied body force. Bubble evolution is analyzed by the nucleation time, critical nucleation volume, bubble volume variation, and migration of the bubble's center of mass. The results show that system pressure and substrate temperature dominantly regulate the nucleation: increasing pressure delays nucleation, whereas increasing substrate temperature accelerates it. Under a fixed system pressure and substrate temperature, liquid flow exhibits a non-monotonic influence. The applied forces from 4.0×10-7 eV/Å to 1.0×10-6 eV/Å gradually promote the nucleation and enhance the bubble growth by facilitating near-substrate heat transfer and density fluctuations, while the forces from 1.0×10-6 eV/Å to 1.4×10-6 eV/Å suppress nucleation and do not further promote the growth due to the intensified shear and interfacial instability. These findings provide molecular-level insight into the coupled thermodynamic and kinetic effects of pressure, temperature, and flow on bubble nucleation and growth at material interfaces, offering guidance for the design and operation of heat-transfer and functional materials processes.