Molecular Dynamics Study of Bubble Nucleation on Grooved Surfaces with Instantaneous Substrate Heating Using a Pressure-Control Method

Molecular dynamics simulations were performed to investigate argon bubble nucleation under instantaneous platinum substrate heating, with a pressure-control method. The simulation starts from an equilibrium system consisting of saturated liquid/vapor argon at 90 K. A constant pressure is applied to the pressure-control plate located above the fluid to maintain the target system pressure. At time zero, the substrate temperature is instantaneously increased from 90 K to the target value, while the pressure remains fixed. The substrate temperature ranges from 130 to 150 K, and the system pressure ranges from 2 to 30 atm. Results show that higher substrate temperatures reduce critical nucleation volume and accelerate nucleation, whereas higher pressures enlarge critical nucleation volume and prolong nucleation. Within the substrate temperature and system pressure range, temperature-pressure maps reveal three regimes: low-temperature non-nucleation, intermediate pressure-sensitive transition, and high-temperature easier nucleation. The nucleation time varies from 1 to 15 ns, and the critical nucleation volume from 1 nm³ to 9 nm³. These findings clarify the combined effects of temperature and pressure on bubble nucleation, providing further insights into the thermal management in rapid, localized heating systems with a fluid film.