naa a22 4500 510790712 CHVBK 20180411083318.0 cr unu---uuuuu 180411e20130301xx s 000 0 eng 10.1007/s12289-011-1071-6 doi (NATIONALLICENCE)springer-10.1007/s12289-011-1071-6 The free (open) boundary condition (FBC) in viscoelastic flow simulations [Elektronische Daten] [Evan Mitsoulis, Nikolaos Malamataris] The Free (or Open) Boundary Condition (FBC, OBC) was proposed by Papanastasiou et al. (A New Outflow Boundary Condition, Int. J. Numer. Meth. Fluids, 1992; 14:587-608) to handle truncated domains with synthetic boundaries where the outflow conditions are unknown. In the present work, implementation of the FBC has been extended to viscoelastic fluids governed by explicit differential constitutive equations. As such we consider here the Criminale-Ericksen-Filbey (CEF) model, which also reduces to the Second-Order Fluid (SOF) for constant material parameters. The Finite Element Method (FEM) is used to provide numerical results in simple Poiseuille flow where analytical solutions exist for checking purposes. Then previous numerical results are checked against Newtonian highly non-isothermal flows in a 4:1 contraction. Finally, the FBC is used with the CEF fluid with data corresponding to a Boger fluid of constant material properties. Particular emphasis is based on a non-zero second normal-stress difference, which seems responsible for earlier loss of convergence. The results with the FBC are in excellent agreement with those obtained from long domains, due to the highly convective nature of viscoelastic flows, for which the FBC seems most appropriate. The FBC formulation for fixed-point (Picard-type) iterations is given in some detail, and the differences with the Newton-Raphson formulation are highlighted regarding some computational aspects. Springer-Verlag France, 2011 Free (open) boundary condition nationallicence Viscoelastic flows nationallicence Non-isothermal flows nationallicence Newtonian fluid nationallicence Second-order fluid nationallicence CEF model nationallicence Mitsoulis Evan School of Mining Engineering & Metallurgy, National Technical University of Athens, Zografou, 157 80, Athens, Greece aut Malamataris Nikolaos Department of Mechanical Engineering, TEI of Western Macedonia, GR-50100, Kila-Kozani, Greece aut International Journal of Material Forming Springer-Verlag 6/1(2013-03-01), 49-63 1960-6206 6:1<49 2013 6 12289 https://doi.org/10.1007/s12289-011-1071-6 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s12289-011-1071-6 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Mitsoulis Evan School of Mining Engineering & Metallurgy, National Technical University of Athens, Zografou, 157 80, Athens, Greece aut NATIONALLICENCE 700 1- Malamataris Nikolaos Department of Mechanical Engineering, TEI of Western Macedonia, GR-50100, Kila-Kozani, Greece aut NATIONALLICENCE 773 0- International Journal of Material Forming Springer-Verlag 6/1(2013-03-01), 49-63 1960-6206 6:1<49 2013 6 12289 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer