Author:

Keywords:

critical-point shifts, surfaces, fluids, films, field, Science & Technology, Physical Sciences, Physics, Multidisciplinary, Physics, CRITICAL-POINT SHIFTS, SURFACES, FLUIDS, FILMS, FIELD, 01 Mathematical Sciences, 02 Physical Sciences, Fluids & Plasmas, 49 Mathematical sciences, 51 Physical sciences

Abstract:

We study a fluid or Ising lattice gas confined between two horizontal walls with separation L, in a gravitational field of strength g. For identical walls (with equal surface fields h1 = h(L)) the familiar capillary condensation and capillary criticality extend to non-zero g. Finite-size scaling predicts that the locus of criticality shrinks to g = 0 for L --> infinity, in the manner g is-proportional-to L-(betadelta/nu + 1). For opposing walls (with h1 = - h(L)) we confirm that the bulk two-phase coexistence is suppressed, for g = 0, to below the wetting temperature T(W). However, for small g the bulk two-phase coexistence extends to higher temperatures that increase extremely rapidly with g, up to a maximum temperature that is shifted from the L = infinity bulk critical point in the manner T(c, max)(L) - T(c)(infinity) is-proportional-to L-1/nu, conform with finite-size scaling.