Adsorption of fluids in pores formed between two hard cylinders

We study adsorption in pores with curved hard walls that are made of two un iaxial cylinders by using a density functional approach. Two cases are cons idered: adsorption of hard spheres and adsorption of a Lennard-Jones fluid, In the case of hard spheres, we perform a comparison with the results of g rand canonical ensemble Monte Carlo data. This comparison indicates that th e applied approach is capable of reproducing the fluid structure quite sati sfactorily. For hard spheres, we also make a comparison of the total adsorp tion effect (expressed as the average density of a confined fluid) inside p ores with curved walls with that evaluated for a slitlike pore. We have fou nd that the differences between adsorption in pores with curved walls and i n slits with the same wall-to-wall distance are quite low. The calculations for the Lennard-Jones fluid have been concerned with the investigation of the capillary evaporation and with the evaluation of phase diagrams for dif ferent pores, including slitlike pores. We have found that the curvature of the pore walls shifts the transition toward lower values of the chemical p otential and increases slightly the value of the critical temperature in co mparison with the values obtained for a slitlike pore. (C) 2000 Academic Pr ess.