Transient-time correlation function applied to mixed shear and elongational flows

Hartkamp, Remco; Bernardi, Stefano; Todd, B. D.

doi:doi:10.1063/1.3684753

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The transient-time correlation function (TTCF) method is used to calculate the nonlinear response of a homogeneous atomic fluid close to equilibrium. The TTCF response of the pressure tensor subjected to a time-independent planar mixed flow of shear and elongation is compared to directly averaged non-equilibrium molecular dynamics (NEMD) simulations. We discuss the consequence of noise in simulations with a small rate of deformation. The generalized viscosity for planar mixed flow is also calculated with TTCF. We find that for small rates of deformation, TTCF is far more efficient than direct averages of NEMD simulations. Therefore, TTCF can be applied to fluids with deformation rates which are much smaller than those commonly used in NEMD simulations. Ultimately, TTCF applied to molecular systems is amenable to direct comparison between NEMD simulations and experiments and so in principle can be used to study the rheology of polymer melts in industrial processes.

Article Outline

INTRODUCTION
TRANSIENT-TIME CORRELATION FUNCTION
PLANAR MIXED FLOW
SIMULATIONS
RESULTS AND DISCUSSION
CONCLUSIONS

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KEYWORDS and PACS

Keywords

correlation methods, deformation, flow simulation, molecular dynamics method, polymer melts, shear flow, tensors, viscosity

PACS

47.11.Mn

Molecular dynamics methods
66.20.Ej

Studies of viscosity and rheological properties of specific liquids
62.10.+s

Mechanical properties of liquids

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http://dx.doi.org/10.1063/1.3684753

PUBLICATION DATA

ISSN

0021-9606 (print)

1089-7690 (online)

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$abstract.society.value is a Member of CrossRef

American Institute of Physics

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