Experimental and numerical study of entry flow of low-density polyethylene melts

A quasi-1D model for fast contraction flows of polymer melts

“…In spite of the model arbitrariness and unstable character of original simple integral CE, the authors reported successful agreement between the model calculations and experimental data [18,19].…”

“…After that, the jet extensional force for the next step, x 1 + x 1 , can be computed from Eqs. (19) and (19*). It is easy to understand that the circulatory shear flow model will decrease the jet length l 1 .…”

“…This assumption is directly employed from the Cogswell idea [16] and the flow visualization experiments [7,13,19], where the measured core stress distribution for high De number flows becomes more jet-like near the die. This simplified rough modeling ignores vortices at the entrance corners and neglects the shear effects near the reservoir walls.…”

“…Binding [17] employed empirical equations for simple shearing and simple elongation. Carrot et al [18] and Guillet et al [19] involved employed a specific CE of simple integral type in computations. They calculated the stress-strain rate relations in the "Protean" (stream function-longitudinal) coordinate system known well in the theory of convective diffusion [20].…”

“…The transitions between flow types between different flow regions, except for those in (iii) and (iv), are modeled by specific matching boundary conditions. Unlike many direct [8,[10][11][12][13] and very simplified [17][18][19] flow simulations, the present flow model involves the detailed description of the polymer melt flows in simple shearing and simple elongation, keeping these descriptions with all the rheological complexity (see also the brief discussion in the next section). Nevertheless, the model treats the transient flows in a very rough and simplistic manner based mostly on intuitive assumptions and experimental findings.…”