Condensation coefficient of water in a weak condensation state
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The condensation coefficient of water at a vapor-liquid interface is determined bycombining shock tube experiments and numerical simulations of the Gaussian-BGKBoltzmann equation. The time evolution in thickness of a liquid film, which isformed on the shock tube endwall behind the shock wave reflected at the endwall,is measured with an optical interferometer consisting of the physical beam and thereference one. The reference beam is utilized to eliminate systematic noises fromthe physical beam. The growth rate of the film is evaluated from the measuredtime evolution and it is incorporated into the kinetic boundary condition for theBoltzmann equation. From a numerical simulation using the boundary condition,the condensation coefficient of water is uniquely deduced. The results show that, ina condition of weak condensation near a vapor-liquid equilibrium state, the condensationcoefficient of water is almost equal to the evaporation coefficient estimatedby molecular dynamics simulations near a vapor-liquid equilibrium state and it decreasesas the system becomes a nonequilibrium state. The condensation coefficientof water is nearly identical with that of methanol (Mikami et al., 2006).
- Fluid Dynamics Research
Fluid Dynamics Research 40(7), 585-596, 2008-08-01