TY - JOUR
T1 - Computational studies of nonlinear elastic dumbbell models of Boger fluids in a cross-slot flow
AU - Remmelgas, Johan
AU - Singh, Pushpendra
AU - Leal, L. Gary
N1 - Funding Information:
The completion of this research was supported by a grant from the polymer and GOALI programs of the NSF. LGL also acknowledges the contributions associated with his participation in the complex fluids program at the Isaac Newton Institute, Cambridge, UK. The issue of conformation-dependent friction effects in dilute solution modeling was discussed at the Workshop on Unresolved Experimental Dilemmas in the Dynamics of Complex Fluids as part of that program.
PY - 1999/12/1
Y1 - 1999/12/1
N2 - The flow of a viscoelastic fluid in a cross-slot flow is studied numerically for two different versions of the elastic-dumbbell model, namely, the Chilcott-Rallison model (FENE-CR) and the same model but with conformation-dependent friction modeled via the Hinch-de Gennes scaling (FENE-CD). It is shown that the FENE-CR and FENE-CD models both predict a local reduction in the streamwise velocity downstream of the stagnation point. The reduction in the velocity is shown to result from the presence of highly stretched dumbbells near the streamlines emanating from the stagnation point, and is in reasonable agreement with existing experimental observations on high molecular weight polymer solutions. However, the FENE-CR model is shown to produce a birefringent strand whose length in the streamwise direction is significantly shorter than observed experimentally. Better agreement with experimental observations is found with the FENE-CD model, which exhibits a much slower relaxation from the extended state, thus producing a birefringent strand which extends substantially farther downstream than for the FENE-CR model. The effect of a conformation-dependent friction coefficient similar to the one proposed by Larson [R.G. Larson, The unravelling of a polymer chain in a strong extensional flow, Rheol. Acta 29 (1990) 371-384] is also considered.
AB - The flow of a viscoelastic fluid in a cross-slot flow is studied numerically for two different versions of the elastic-dumbbell model, namely, the Chilcott-Rallison model (FENE-CR) and the same model but with conformation-dependent friction modeled via the Hinch-de Gennes scaling (FENE-CD). It is shown that the FENE-CR and FENE-CD models both predict a local reduction in the streamwise velocity downstream of the stagnation point. The reduction in the velocity is shown to result from the presence of highly stretched dumbbells near the streamlines emanating from the stagnation point, and is in reasonable agreement with existing experimental observations on high molecular weight polymer solutions. However, the FENE-CR model is shown to produce a birefringent strand whose length in the streamwise direction is significantly shorter than observed experimentally. Better agreement with experimental observations is found with the FENE-CD model, which exhibits a much slower relaxation from the extended state, thus producing a birefringent strand which extends substantially farther downstream than for the FENE-CR model. The effect of a conformation-dependent friction coefficient similar to the one proposed by Larson [R.G. Larson, The unravelling of a polymer chain in a strong extensional flow, Rheol. Acta 29 (1990) 371-384] is also considered.
KW - Boger fluids
KW - Elastic-dumbbell model
KW - FENE-CD model
KW - FENE-CR model
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U2 - 10.1016/S0377-0257(99)00020-8
DO - 10.1016/S0377-0257(99)00020-8
M3 - Article
AN - SCOPUS:0033394613
SN - 0377-0257
VL - 88
SP - 31
EP - 61
JO - Journal of Non-Newtonian Fluid Mechanics
JF - Journal of Non-Newtonian Fluid Mechanics
IS - 1-2
ER -