  A three-phase contact line in a three-phase fluid system is modeled by a
mean-field density functional theory. We use a variational approach to find the
Euler-Lagrange equations. Analytic solutions are obtained in the two-phase
regions at large distances from the contact line. We employ a triangular grid
and use a successive over-relaxation method to find numerical solutions in the
entire domain for the special case of equal interfacial tensions for the
two-phase interfaces. We use the Kerins-Boiteux formula to obtain a line
tension associated with the contact line. This line tension turns out to be
negative. We associate line adsorption with the change of line tension as the
governing potentials change.
