A molecular dynamics simulation of a bubble nucleation on solid surface
In order to understand the molecular level phenomena related to the phase-change heat transfer, the authors are performing molecular dynamics simulations of a liquid droplet and a vapor bubble. Since many of practical nucleation phenomena are on the solid surface, the authors are paying special attention to the effect of a solid surface. Here, a heterogeneous nucleation of a vapor bubble on a solid surface was simulated by the molecular dynamics method. Liquid argon between parallel solid surfaces was gradually expanded, until a vapor bubble was nucleated. Argon liquid was represented by 5488 Lennard-Jones molecules and each solid surface was represented by three layers of harmonic molecules with the constant temperature heat bath model using the phantom molecules out side of the three-layers. They used a quite wettable potential parameter on the top surface and changed the wettability on the bottom surface. The wettability was varied by changing the potential parameter between argon and solid molecule. After the equilibrium of liquid between two solid surfaces was obtained, they slowly expanded the surfaces. According to the increase in volume, the decrease of pressure was observed. There appeared patches of liquid where the local potential was considerably high. These patches appeared and disappeared randomly in space and time. Finally, at some point of the decrease of the pressure, one of the patches successfully grew to a vapor bubble on the bottom solid surface. Observed pressure showed the minimum at this time of the nucleation. They compared the minimum pressure for various surface potential conditions. With the increase in the surface wettability, the minimum pressure approached to the spinodal line. After the stable vapor bubble was formed on the surface, the authors stopped the expansion and observed the equilibrium structure of the vapor bubble. After averaging the two-dimensional density and potential distributions, they could define the contact angle. The contact angle was well correlated to the depth of the integrated effective surface potential in excellent agreement with the case of liquid droplet in contact with the surface.
- Research Organization:
- Univ. of Tokyo (JP)
- OSTI ID:
- 20034241
- Resource Relation:
- Conference: 5th ASME/JSME Thermal Engineering Joint Conference, San Diego, CA (US), 03/14/1999--03/19/1999; Other Information: 1 CD-ROM. Operating system required: Windows i386(tm), i486(tm), Pentium (R) or Pentium Pro, MS Windows 3.1, 95, or NT 3.51, 8 MB RAM, MacIntosh and Power MacIntosh with a 68020 or greater processor, System software version 7.1, 3.5 MB RAM (5 MB for PowerMac) 6 MB available hard-disk space, Unix; PBD: 1999; Related Information: In: Proceedings of the 5th ASME/JSME thermal engineering joint conference, [3600] pages.
- Country of Publication:
- United States
- Language:
- English
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