Uniform flow of viscoelastic fluids past a confined falling cylinder |
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Authors: | Alexandre Afonso Manuel A Alves Fernando T Pinho Paulo J Oliveira |
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Institution: | 1.Departamento de Engenharia Química, CEFT,Faculdade de Engenharia da Universidade do Porto,Porto,Portugal;2.Universidade do Minho,Braga,Portugal;3.Centro de Estudos de Fenómenos de Transporte,Faculdade de Engenharia da Universidade do Porto,Porto,Portugal;4.Departamento de Engenharia Electromecanica, Unidade de Materiais Têxteis e Papeleiros,Universidade da Beira Interior,Covilh?,Portugal |
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Abstract: | Uniform steady flow of viscoelastic fluids past a cylinder placed between two moving parallel plates is investigated numerically
with a finite-volume method. This configuration is equivalent to the steady settling of a cylinder in a viscoelastic fluid,
and here, a 50% blockage ratio is considered. Five constitutive models are employed (UCM, Oldroyd-B, FENE-CR, PTT and Giesekus)
to assess the effect of rheological properties on the flow kinematics and wake patterns. Simulations were carried out under
creeping flow conditions, using very fine meshes, especially in the wake of the cylinder where large normal stresses are observed
at high Deborah numbers. Some of the results are compared with numerical data from the literature, mainly in terms of a drag
coefficient, and significant discrepancies are found, especially for the constant-viscosity constitutive models. Accurate
solutions could be obtained up to maximum Deborah numbers clearly in excess of those reported in the literature, especially
with the PTT and FENE-CR models. The existence or not of a negative wake is identified for each set of model parameters. |
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Keywords: | Falling cylinder Viscoelastic UCM Oldroyd-B FENE-CR PTT Giesekus Negative wake Numerical simulations |
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