Effects of compressibility and wetting on the liquid-vapor transition in a confined fluid

Abstract

When a fluid is constrained to a fixed, finite volume, the conditions for liquid-vapor equilibrium are different from those for the infinite volume or constant pressure cases. There is even a range of densities for which no bubble can form, and the liquid at a pressure below the bulk saturated vapor pressure remains indefinitely stable. As the fluid density in mineral inclusions is often derived from the temperature of bubble disappearance, a correction for the finite volume effect is required. Previous works have explained these phenomena and proposed a numerical procedure to compute the correction for pure water in a container completely wet by the liquid phase. Here, we revisit these works and provide an analytic formulation valid for any fluid, including the case of partial wetting. We introduce the Berthelot-Laplace length λ = 2γκ/3, which combines the liquid isothermal compressibility κ and its surface tension γ. The quantitative effects are fully captured by a single, nondimensional parameter: the ratio of λ to the container size.