COMPARISON OF SHEAR-FLOW OF HEXADECANE IN A CONFINED GEOMETRY AND IN BULK

We examine the shear flow of hexadecane confined between plates with s eparation of 1-10 nm using molecular dynamics simulations. We also per formed non-equilibrium molecular dynamics (NEMD) simulations of bulk h exadecane to compare with the simulations in the confined geometry. Th e stiffness of hexadecane and its high melting temperature result in a tendency to crystallize at room temperature or large load. We find th at when confined between hydrocarbon walls, shearing hexadecane exhibi ts a velocity profile with substantial slip at the wall and essentiall y constant velocity over most of the interior space between the walls. As the strength of the wall-fluid interaction increases the amount of slip decreases, but slip always occurs at the boundary for the range of parameters studied. The results are compared with recent surface fo rce apparatus experiments on hexadecane and with similar simulations o f model bead-spring fluids. (C) 1997 American Institute of Physics.