In this work, a hard sphere fluid confined between two homocentric cylinders which formed a bicylindrical pore has been investigated. Our aim is investigation of the effect of an outer cylinder on the values of wall pressure, interfacial tension, and excess adsorption of fluid at a convex nanocylindrical wall, inner wall. To investigate this effect, the modified fundamental measure theory (MFMT) used. To do so at first we presented a general solution for weighted density integrals in cylindrical coordinate which is applicable for infinite and infinite lengths of cylindrical pore, bicylindrical pore, cylindrical wall, and even truncated cone. In the second step, the wall pressures, interfacial tensions, and excess adsorptions at a convex nanocylindrical wall are obtained for confined fluids in bicylindrical pores and compared with those values for bulk fluids. Our results showed that confinement leads to an oscillatory behavior for wall pressure, interfacial tension, and excess adsorption of the fluid at the wall. The reason for these oscillations lies in structural changes that occur for a fluid as a result of confinement. Variation of the type of interaction of inner wall with fluid from hard to attractive one can reverse the behavior of interfacial tension and adsorption versus size. Also in some cases, it changes their signs while the change in the type of interaction of the outer wall only leads to an increase in amplitudes of the oscillations. The modified fundamental measure theory has been employed to investigate some well-known regularities of bulk fluids for the Lennard-Jones fluids confined in nanoslit pores. The regularities investigated include common compression point, common bulk modulus point, Tait-Murnaghan equation, and the linear regularity between pressure and temperature for each isochore. All these regularities have been investigated for two different components of pressure for confined fluid. Our results show that the common compression and common bulk modulus point remain valid for fluids confined in nanoslit pores of different sizes and with different wall-fluid potentials. The density of the common compression and common bulk modulus point are different from corresponding ones for the bulk fluid. Our observations also show that the Tait-Murnaghan equation and pressure?temperature linear regularity also hold for confined fluid. The sign of the intercept of pressure?temperature regularity is determined by the difference between attraction and repulsion terms in the compressibility factor.
