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Shear Rate Threshold For The Boundary Slip In Dense Polymer Films, Nikolai V. Priezjev
Shear Rate Threshold For The Boundary Slip In Dense Polymer Films, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
The shear rate dependence of the slip length in thin polymer films confined between atomically flat surfaces is investigated by molecular dynamics simulations. The polymer melt is described by the bead-spring model of linear flexible chains. We found that at low shear rates the velocity profiles acquire a pronounced curvature near the wall and the absolute value of the negative slip length is approximately equal to thickness of the viscous interfacial layer. At higher shear rates, the velocity profiles become linear and the slip length increases rapidly as a function of shear rate. The gradual transition from no-slip to steady-state …
The Effective Slip Length And Vortex Formation In Laminar Flow Over A Rough Surface, Anoosheh Niavarani, Nikolai V. Priezjev
The Effective Slip Length And Vortex Formation In Laminar Flow Over A Rough Surface, Anoosheh Niavarani, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
The flow of viscous incompressible fluid over a periodically corrugated surface is investigated numerically by solving the Navier–Stokes equation with the local slip and no-slip boundary conditions. We consider the effective slip length which is defined with respect to the level of the mean height of the surface roughness. With increasing corrugation amplitude the effective no-slip boundary plane is shifted toward the bulk of the fluid, which implies a negative effective slip length. The analysis of the wall shear stress indicates that a flow circulation is developed in the grooves of the rough surface provided that the local boundary condition …