A theoretical and experimental study of the equilibrium interface configuration in stratified bicomponent tube flow of polymer melts is presented. In the theoretical analysis, the principle of minimum viscous dissipation is used to determine the energetically preferred interface configuration for the case of stratified flow of Newtonian fluids of differing viscosity. In the experimental analysis, it is demonstrated that both a nylon-nylon and a xylene-sugar water solution system attain the minimum viscous dissipation interface configuration under equilibrium conditions.

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An approximate theoretical analysis of transient bicomponent flow and interface motion in the entrance region of infinite parallel plates is presented, and an estimate of the entry length required to attain equilibrium flow is obtained. The theoretical predictions are compared with experimental measurements of interface configuration and extrudate bending in the bicomponent tube flow of a nylon/nylon system. The results indicate that interface motion takes place at two distinct rates in the tube flow case. Initially a very rapid interface movement occurs which is qualitatively described by the theoretical parallel plate analysis. This is followed by a very slowly occurring interface curvature which has no apparent counterpart in the parallel plate case considered here.

Recently Champagne, Harris, and Corrsin ( 2 ) have measured turbulence properties in a nearly homogeneous shear flow where far downstream of a shear-turbulence generator, the turbulence has reached a nearly homogeneous asymptotic condition with constant values of the mean velocity gradient and the one-point turbulence moments. The present note interprets the experimental results in terms of Phillips' hypothesis. The experimentally measured value of the eddy viscosity ve is found to be 0.0144 sq. ft./sec. The Eulerian space-time correlation of CONSTITUTIVE EQUATIONGordon and Schowalter recently presented a modification of the dumbbell theory of dilute polymer solutions ( 1 2 ) , based on a structured fluid theory of Ericksen ( 1 3 ) . Gordon and Everage used this result to obtain an explicit constitutive equation ( 1 4 ) , namely

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