Nonequilibrium molecular dynamics simulations of a bubble.

Area of Science:

• Thermodynamics
• Fluid Dynamics
• Computational Physics

Background:

• Understanding bubble dynamics is crucial in various physical processes.
• Microscopic bubble formation and behavior under local heating are not fully understood.
• Bridging the gap between microscopic atomic interactions and macroscopic hydrodynamic descriptions is challenging.

Purpose of the Study:

• To investigate the microscopic dynamics of bubble formation and evolution in locally heated liquids.
• To compare simulation results with established macroscopic hydrodynamic models.
• To determine the validity of hydrodynamic descriptions for microscopic bubbles.

Main Methods:

• Utilizing molecular dynamics simulations to model atomic interactions.
• Simulating the local heating of liquid atoms.
• Observing and analyzing bubble formation, expansion, cooling, and compression.
• Comparing simulation data with the Rayleigh-Plesset equation.

Main Results:

• Successfully observed heated atoms scattering to form a microscopic bubble.
• Documented the bubble's subsequent cooling and compression by surrounding liquid.
• Demonstrated agreement between simulated bubble dynamics and the Rayleigh-Plesset equation.
• Confirmed that macroscopic hydrodynamic descriptions are reliable for microscopic bubbles.

Conclusions:

• Molecular dynamics simulations provide detailed insights into microscopic bubble dynamics.
• The formation and collapse of microscopic bubbles are governed by atomic scattering and surrounding fluid pressure.
• The Rayleigh-Plesset equation accurately describes the macroscopic behavior of these microscopic bubbles.
• Hydrodynamic models are robust and applicable even at the microscopic scale for bubble dynamics.