Molecular mechanism for cavitation in water under tension.
Despite its relevance in biology and engineering, the molecular mechanism driving cavitation in water remains unknown. Using computer simulations, we investigate the structure and dynamics of vapor bubbles emerging from metastable water at negative pressures. We find that in the early stages of cavitation, bubbles are irregularly shaped and become more spherical as they grow. Nevertheless, the free energy of bubble formation can be perfectly reproduced in the framework of classical nucleation theory (CNT) if the curvature dependence of the surface tension is taken into account. Comparison of the observed bubble dynamics to the predictions of the macroscopic Rayleigh-Plesset (RP) equation, augmented with thermal fluctuations, demonstrates that the growth of nanoscale bubbles is governed by viscous forces. Combining the dynamical prefactor determined from the RP equation with CNT based on the Kramers formalism yields an analytical expression for the cavitation rate that reproduces the simulation results very well over a wide range of pressures. Furthermore, our theoretical predictions are in excellent agreement with cavitation rates obtained from inclusion experiments. This suggests that homogeneous nucleation is observed in inclusions, whereas only heterogeneous nucleation on impurities or defects occurs in other experiments.
Faculty of Physics, University of Vienna, 1090 Vienna, Austria.|Center for Computational Materials Science, University of Vienna, 1090 Vienna, Austria.
Georg
G
Menzl
Department of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom.
Miguel A
MA
Gonzalez
Faculty of Physics, University of Vienna, 1090 Vienna, Austria.|Center for Computational Materials Science, University of Vienna, 1090 Vienna, Austria.
Philipp
P
Geiger
Institut Lumière Matière, UMR5306 Université Claude Bernard Lyon 1, CNRS, Université de Lyon, Institut Universitaire de France, 69622 Villeurbanne, France.
Frédéric
F
Caupin
Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain.
José L F
JL
Abascal
Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain.|Departamento de Física Aplicada I, Facultad de Ciencias Física, Universidad Complutense de Madrid, 28040 Madrid, Spain.
Chantal
0000-0002-0502-4648
C
Valeriani
Faculty of Physics, University of Vienna, 1090 Vienna, Austria; christoph.dellago@univie.ac.at.|Center for Computational Materials Science, University of Vienna, 1090 Vienna, Austria.
Christoph
C
Dellago
bubble nucleation; cavitation; liquid–vapor transition; negative pressure; water