Viscous Heating Effects in Viscoelastic Flow between Rotating Parallel-Disks

Authors: BÜLENT YEŞİLATA

Abstract: Viscoelastic flow between two rotating parallel-disks (plates) is studied. First the current state of the art is discussed and the limitations resulting from the simple flow assumptions are reported. In an attempt to consider the effects of finiteness of the plates and viscous dissipation, the flow problem is fully formulated; that is, no assumptions are made about the three-dimensional and nonisothermal nature of the flow. One of the major contributions to the formulation is to use a nonisothermal constitutive equation, the nonisothermal Oldroyd-B equation. In this case, the numerical solution scheme of resulting equations is too complex, even for the Oldroyd-B model, which is considered one of the simplest constitutive equations for polymeric flows. Instead, the problem is reduced to a one-dimensional nonisothermal infinite plate problem and the viscous dissipation effect is then investigated. It is determined here that the viscous dissipation effect results in a significant temperature rise in the flow field and may yield errors in the prediction of the material properties of highly viscous and elastic fluids. Some simple modifications in existing equations used for the prediction of fluid-material properties are proposed by considering viscous dissipation and free surface effects.

Keywords: Polymeric (Viscoelastic) fluid, Parallel-Disks, Rheometry, Nonisothermal, Viscous dissipation effect.

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