Showing papers by "Kenneth Walters published in 1979"
TL;DR: In this article, a finite difference solution is obtained for the problem generated by the presence of a protruberance in a basic two-dimensional Couette flow, and a refinement of the numerical method used in Parts 1 and 2 is presented.
Abstract: Further consideration is given to the use of implicit rheological equations in the solution of complex flow problems A finite difference solution is obtained for the problem generated by the presence of a protruberance in a basic two-dimensional Couette flow New features of the work include (i) a refinement of the numerical method used in Parts 1 and 2, (ii) the applicability (or otherwise) of explicit rheological models of the “second-order” type, (iii) the handling of the differential boundary conditions on the stress components brought about by the moving boundary in Couette flow
29 citations
TL;DR: A review of existing work in continuum non-Newtonian fluid mechanics concludes that a unifying and helpful picture emerges when the best of the work associated with the various strands of research is taken into account.
Abstract: The review begins with a critical assessment of existing work in continuum non-Newtonian fluid mechanics. To facilitate this, relevant papers are divided into three categories, these being associated with (i) slow flow or slightly elastic liquids, (ii) nearly viscometric flows and (iii) complex flows. A general argument is then developed which deprecates too much emphasis on one particular strand of research, whether this is associated with a preoccupation with “generality” or with the need to be “practically relevant”. By drawing attention to certain case histories, the review concludes that a unifying and helpful picture emerges when the best of the work associated with the various strands of research is taken into account.
27 citations
TL;DR: In this paper, the authors consider the effect of variable-viscosity behavior on the departure of the predicted shear rate from that used in the conventional interpretation of experimental results.
Abstract: We consider theoretically the problem of the shear rate in a cone-and-plate rheometer, giving particular attention to the effect of variable-viscosity behaviour on the departure of the predicted shear rate from that used in the conventional interpretation of experimental results. It is concluded that this departure is much greater for shear-thinning fluids than for Newtonian constant-viscosity fluids. It is also shown that edge effects are significantly enhanced by variable-viscosity behaviour. However, the predicted departure from the constant shear-rate normally assumed is still insignificant for gap angles usually employed in cone-and plate rheometers (≤ 4°). Some consideration is also given toLodge's proposed method of normal-stress measurement which uses a truncated cone-and-plate assembly. It is concluded that the assumptions required to interpret the experimental results are valid to a sufficient degree of approximation. These assumptions concern the smooth transition from torsional flow to cone-and-plate flow near the abrupt change in geometry. Finally, we discuss edge effects in the re-entrant cone situation suggested byCowsley. These are concluded to be significant, pointing to a serious source of experimental error.
4 citations