Numerical simulation of abrupt contraction flows using the Double Convected Pom–Pom model

Clemeur, N.; Rutgers, R. P. G.; Debbaut, B.

doi:10.1016/j.jnnfm.2004.02.001

Cited by 45 publications

(70 citation statements)

References 44 publications

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“…They [3][4][5] found quantitative agreement between experiments and model predictions for other rheological measurements such as transient shear viscosity and transient first normal stress difference for LDPE.…”

mentioning

confidence: 63%

Numerical Predictions of Viscoelastic Fluid in Pipe Flow Using Extended Pom-Pom Model

Khorsand

Rashidi

Goharpey

et al. 2011

J. Soc. Rheol., Jpn

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In this study prediction of the steady-state flow of branched polymer melts in pipe geometry with finite volume method is presented. The fluid is modelled using a modification of the Pom-Pom model known as the single eXtended Pom-Pom (XPP) where viscoelastic fluid, is typically a commercial low-density polyethylene. In finite volume method, the operator-integration is used to discretize the governing equations in space or control volume. An iterative solution algorithm that decouples the computation of momentum from that of stress is used to solve the discrete equations. Numerical results are presented; include the profiles of all relevant stresses, the axial velocity, stretch and the viscosity across the gap, demonstrating the performance of the model predictions. The influence of the model parameters on the solution and flow behaviour is described and, in particular, the dependence of velocity and stresses distribution as a function of Weissenberg number is analyzed. Finally, for rectitude and accuracy, the verification of this model is performed with the Gieskus model that shows good conformity between the results.

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mentioning

confidence: 63%

Numerical Predictions of Viscoelastic Fluid in Pipe Flow Using Extended Pom-Pom Model

Khorsand

Rashidi

Goharpey

et al. 2011

J. Soc. Rheol., Jpn

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“…In addition, the transverse isotropic behavior of results predicted by the PTT model is the most obvious one, in which the E 22 . and G 13 are unique values and E 11 , E 33 as well as G 12 , G 23 show high agreement. Our material stiffness predictions agree remarkably well with test data appearing in the literature.…”

Section: Elastic Properties Across the Exrudatementioning

confidence: 78%

“…A good agreement between the numerical results and the experimental data was achieved. Clemeur et al [23] found that the SV model was a cost-effective approach for evaluating the flow-viscoelasticity as compared to conventional viscoelastic fluid flow models including the Oldroyd-B and the Phan-Thien-Tanner models.…”

Section: Introductionmentioning

confidence: 99%

Rheology Effects on Predicted Fiber Orientation and Elastic Properties in Large Scale Polymer Composite Additive Manufacturing

Wang

Smith

2018

J. Compos. Sci.

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Short fiber-reinforced polymers have recently been introduced to large-scale additive manufacturing to improve the mechanical performances of printed-parts. As the short fiber polymer composite is extruded and deposited on a moving platform, velocity gradients within the melt orientate the suspended fibers, and the final orientation directly affects material properties in the solidified extrudate. This paper numerically evaluates melt rheology effects on predicted fiber orientation and elastic properties of printed-composites in three steps. First, the steady-state isothermal axisymmetric nozzle melt flow is computed, which includes the prediction of die swell just outside the nozzle exit. Simulations are performed with ANSYS-Polyflow, where we consider the effect of various rheology models on the computed outcomes. Here, we include Newtonian, generalized Newtonian, and viscoelastic rheology models to represent the melt flow. Fiber orientation is computed using Advani-Tucker fiber orientation tensors. Finally, elastic properties in the extrudate are evaluated based from predicted fiber orientation distributions. Calculations show that the Phan-Thien-Tanner (PTT) model yields the lowest fiber principal alignment among considered rheology models. Furthermore, the cross section averaged elastic properties indicate a strong transversely isotropic behavior in these composites, where generalized Newtonian models yield higher principal Young's modulus, while the viscoelastic fluid models result in higher shear moduli.

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“…(3) when it is re-expressed in terms of S rather than in terms of A. In the second version, the chain is considered to diffuse within a stretched backbone tube hence the orientation relaxation time is amplified by B¼k 2 [Verbeeten et al (2001); Clemeur et al (2003Clemeur et al ( , 2004]. This form of the orientation equation can also be derived from the stretching version of the Rolie-Poly model for linear polymers ] in the absence of constraint release, by splitting the stress tensor in that model into tensor orientation and scalar stretch components.…”

Section: The Overshoot Model: the Constitutive Equationmentioning

confidence: 99%

Modifying the pom-pom model for extensional viscosity overshoots

Hawke¹,

Huang²,

Hassager³

et al. 2015

Journal of Rheology

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We have developed a variant of the pom-pom model that qualitatively describes two surprising features recently observed in filament stretching rheometer experiments of uniaxial extensional flow of industrial branched polymer resins: (i) Overshoots of the transient stress during steady flow and (ii) strongly accelerated stress relaxation upon cessation of the flow beyond the overshoot. Within the context of our model, these overshoots originate from entanglement stripping (ES) during the processes of normal chain retraction and branch point withdrawal. We demonstrate that, for a single mode, the predictions of our overshoot model are qualitatively consistent with experimental data. To provide a quantitative fit, we represent an industrial melt by a superposition of several individual modes. We show that a minimal version of our model, in which ES due to normal chain retraction is omitted, can provide a reasonable, but not perfect, fit to the data. With regard the stress relaxation after (kinematically) steady flow, we demonstrate that the differential version of tube orientation dynamics in the original pom-pom model performs anomalously. We discuss the reasons for this and suggest a suitable alternative. V C 2015 The Society of Rheology.[http://dx

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Numerical simulation of abrupt contraction flows using the Double Convected Pom–Pom model

Cited by 45 publications

References 44 publications

Numerical Predictions of Viscoelastic Fluid in Pipe Flow Using Extended Pom-Pom Model

Numerical Predictions of Viscoelastic Fluid in Pipe Flow Using Extended Pom-Pom Model

Rheology Effects on Predicted Fiber Orientation and Elastic Properties in Large Scale Polymer Composite Additive Manufacturing

Modifying the pom-pom model for extensional viscosity overshoots

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