Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
A method for implementing time-integral 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 NON-NEWTONIAN FLUID MECHANICS
fascicolo: 3, volume: 86, anno: 1999,
pagine: 337 - 357
SICI:
0377-0257(19990930)86:3<337:AMFITC>2.0.ZU;2-I
Fonte:
ISI
Lingua:
ENG
Soggetto:
HIGH-DENSITY POLYETHYLENE; NUMERICAL PREDICTION; CONTRACTION FLOWS; VISCOELASTIC FLUIDS; ABRUPT CONTRACTION; EXTRUDATE SWELL; VORTEX GROWTH; MELTS;
Keywords:
viscoelastic; constitutive; time-integral; 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 time-integral constitutive equations in commercial CFD packages", J NON-NEWT, 86(3), 1999, pp. 337-357

Abstract

A method is described for obtaining viscoelastic flow solutions, based upon time-integral 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 body-forces from a file. Two methods of velocity adjustment were compared: an incremental method and a method whereby the viscoelastic stresses were incorporated directly as body-forces. Results and convergence from the two methods were found to be essentially identical, hence the direct body-force method (which is considerably easier to implement) is described in detail. The method is applied to a well-known 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