NO-SLIP CONDITION FOR A MIXTURE OF 2 LIQUIDS

When a mixture of two viscous liquids flows past a solid wall there is an ambiguity in the use of the no-slip boundary condition. It is not obvious whether the mass-averaged velocity, the volume-averaged veloci ty, the individual species velocities, all of the above, or none of th e above should exhibit no slip. Extensive molecular dynamics simulatio ns of the Poiseuille flow of mixtures of coexisting liquid species pas t an atomistic wall indicate that the velocity of each individual liqu id species satisfies the no-slip condition and, therefore, so do mass and volume averages.