Zur Durchflu�charakteristik von Sch�ttungen bei der Durchstr�mung mit verd�nnten L�sungen aus langkettigen Hochpolymeren

The creeping motion of immiscible drops through a converging/diverging tube

“…The data plotted in this fashion show a systematic increase in the deviation from 'power-law' (or purely viscous) fluid behaviour with increase of De, as expected. Similar experimental results were obtained by Michele (1977), Franzen (1979 and Deiber & Schowalter (1981) These experiments on the motion of a single-phase fluid through the wavy-wall tube serve primarily to verify the relevance of the effective tube radius rHP• and quantities derived from rHP• such as the characteristic velocity V for purposes of data correlation under conditions of the present experiments. Let us now turn to the primary subject of our paper, the motion of suspended large drops through the wavy-wall tube.…”

“…Pressure drop data for viscoelastic fluids in a straight-wall tube have been shown by many authors t o follow the Hagen-Poiseuille law provided that a generalized Reynolds number is employed which incorporates the power-law parameters m and n (equation under some conditions in the wavy-wall tube, the results of 33.1 on Newtonian fluids suggest that these effects should be manifested by systematic deviations from the power-law fluid correlation. Experimental observations of flow of polymer solutions through a tube with abrupt alternate expansions and contractions by Michele (1977), of flow through several periodic tube geometries by Franzen (1979), and of flow through granular beds, packed beds and bundles of capillary tubes by Marshall & Metzner (1967), Savins (1969), James & McLaren (1975) and Elata et al (1977), suggest that departures (sometimes dramatic) from a linear relationship between f and Re, which takes into account shear-thinning of the fluid and the physical structure of the porous matrix, occur when the characteristic relaxation time of thc fluid is comparable to the characteristic convective time ; then, apparently, dynamics of the flow are governed, in part, by the elastic response of the fluid. A convenient measure of the intrinsic relaxation time for the fluid relative to the characteristic timescale for Lagrangian unsteady flow is the Deborah number.…”

Viscoelastic effects in non-Newtonian flows through porous media

“…Consequently, the behavior of viscoelastic liquids in laminar flow through porous media has been the subject of numerous investigations; see for example [1][2][3][4][5][6][7][8]. Consequently, the behavior of viscoelastic liquids in laminar flow through porous media has been the subject of numerous investigations; see for example [1][2][3][4][5][6][7][8].…”

“…Consequently, the behavior of viscoelastic liquids in laminar flow through porous media has been the subject of numerous investigations; see for example [1][2][3][4][5][6][7][8]. Most predictions of "shear thickening", relative to the zero-shear solution viscosity, have been based on some critical value of a dimensionless group, generally a Deborah number [1][2][3][4][5][6][7][8]. Most predictions of "shear thickening", relative to the zero-shear solution viscosity, have been based on some critical value of a dimensionless group, generally a Deborah number [1][2][3][4][5][6][7][8].…”

Particulate systems

“…The nature of the polymer solution and the geometry of the bed interact in a complex manner. For instance, Marshall and Metzner (1967) observed visco-elastic effects at De Ӎ 0.05-0.06 whereas Michele (1977) reported the critical value of De to be as large as 3! The main difficulty stems from the fact that there is no simple method of calculating the value of λ f in an unambiguous manner; some workers have inferred its value from steady shear data (first normal stress difference and/or shear viscosity) while others have used transient rheological tests to deduce the value of λ f .…”