Gravity Effects near the Gas-Liquid Critical Point

The "linear-model" parametric equation of state of Schofield, Litster, and Ho is used to analyze the effect of gravity near the gas-liquid critical point of a fluid. Detailed results are presented on the density distribution as a function of height, the constant-volume specific heat, and the low-frequency sound velocity, for arbitrary points in the ($\rho , T$) plane near the critical point. The influence of gravity on the determination of critical exponents is also considered. It is concluded that even for the thinnest practical samples, gravity corrections may have a significant effect on the exponents. The present theory permits gravity corrections to be made in a self-consistent way, with high accuracy.