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THMT-18. Turbulence Heat and Mass Transfer 9 Proceedings of the Ninth International Symposium On Turbulence Heat and Mass Transfer
July, 10-13, 2018, Rio de Janeiro, Brazil

DOI: 10.1615/THMT-18


ISBN Print: 978-1-56700-468-7

ISBN Online: 978-1-56700-467-0

ISSN Print: 2377-2816

A new elastic dumbbell model with variable affinity in multi-scale analysis of polymer-diluted turbulent flow

pages 913-921
DOI: 10.1615/THMT-18.990
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Краткое описание

We consider turbulent flows diluted with the polymers. The polymer chains are modeled as elastic dumbbells and represented by Brownian dynamics, while the motion of solvent fluid is pursued by DNS (BDS-DNS). Affinity in the motion of the bead-spring configuration with the fluid surrounding the dumbbells is commonly assumed, but it results in emergence of Elasto-inertial turbulence (EIT) regime in which the polymers remove more energy from the large scales than they can dissipate and transfer the excess energy back into the turbulent dissipative scales. When the polymers are highly stretched, molecular motions may not precisely correspond to the macroscopic deformation. We develop a new dumbbell model in which the affine constraint is relaxed and non-affinity is introduced by allowing slippage of the dumbbells against the deformation of solvent. The slip parameter is adjusted so that new orientation of the rotated dumbbell is properly represented. We conduct its assessment in the BDS-DNS of forced homogeneous isotropic turbulence. It is shown that the dumbbells obtained from the case with complete affinity tend to be rotated and converted to the alignment of the dumbbells in the complete non-affine case, and vice versa. This alteration of configurations is repeated quasi-periodically with the temporal intervals comparable to the relaxation time. The largest stretching of the dumbbells and elastic energy production are achieved in the complete non-affine dumbbells. In the proposed model, appearance of EIT is eliminated and de Gennes hypothesis is justified.

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