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Titolo: A method for implementing timeintegral constitutive equations in commercial CFD packages
Autore: Olley, P; Spares, R; Coates, PD;
 Indirizzi:
 Univ Bradford, IRC Polymer Technol, Dept Mech & Med Engn, Bradford BD7 1DP, W Yorkshire, England Univ Bradford Bradford W Yorkshire England BD7 1DP , W Yorkshire, England
 Titolo Testata:
 JOURNAL OF NONNEWTONIAN FLUID MECHANICS
fascicolo: 3,
volume: 86,
anno: 1999,
pagine: 337  357
 SICI:
 03770257(19990930)86:3<337:AMFITC>2.0.ZU;2I
 Fonte:
 ISI
 Lingua:
 ENG
 Soggetto:
 HIGHDENSITY POLYETHYLENE; NUMERICAL PREDICTION; CONTRACTION FLOWS; VISCOELASTIC FLUIDS; ABRUPT CONTRACTION; EXTRUDATE SWELL; VORTEX GROWTH; MELTS;
 Keywords:
 viscoelastic; constitutive; timeintegral; convergence; CFD;
 Tipo documento:
 Article
 Natura:
 Periodico
 Settore Disciplinare:
 Physical, Chemical & Earth Sciences
 Engineering, Computing & Technology
 Citazioni:
 24
 Recensione:
 Indirizzi per estratti:
 Indirizzo: Olley, P Univ Bradford, IRC Polymer Technol, Dept Mech & Med Engn, Bradford BD7 1DP, W Yorkshire, England Univ Bradford Bradford W Yorkshire EnglandBD7 1DP hire, England



 Citazione:
 P. Olley et al., "A method for implementing timeintegral constitutive equations in commercial CFD packages", J NONNEWT, 86(3), 1999, pp. 337357
Abstract
A method is described for obtaining viscoelastic flow solutions, based upon timeintegral constitutive equations, using a general purpose CFD package. The method is general enough to be applied to any available software thathas rudimentary input and output facilities and can solve a Stoke's flow problem. From this basis, flexibility of choice of constitutive equation andcomputational techniques is available. The method is presented in a form appropriate for solving both planar and axisymmetric flows. Delaunay triangulation is used to reconstruct a mesh for external code, and stress computation procedures are performed on this mesh. The method has only two particular requirements for the CFD package used  it must be able to output nodal values (of position and velocity) to file and it must be able to read bodyforces from a file. Two methods of velocity adjustment were compared: an incremental method and a method whereby the viscoelastic stresses were incorporated directly as bodyforces. Results and convergence from the two methods were found to be essentially identical, hence the direct bodyforce method (which is considerably easier to implement) is described in detail. The method is applied to a wellknown flow problem of LDPE melt through a 4 : 1 abrupt contraction axisymmetric die. Convergence was obtained up to nearly the highest value of apparent shear rate for which published simulation results are available. Quantitative results for vortex strength, vortex opening angle and Couette correction are presented which are compared with earlier work on the problem using other methods. Agreement is generally good, giving confidence in the method. Simulations of planar flows of the same melt are performed: a decreasing corner vortex was observed. This phenomenon hasbeen observed experimentally for flows of other substances, but is not expected for flows of LDPE melt. A parametric study of a critical strain hardening parameter is conducted to help explain the cause of the results. (C) 1999 Elsevier Science B.V. All rights reserved.
ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 29/11/20 alle ore 03:05:00