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Non-linear stress response of non-gap-spanning magnetic chains suspended in a newtonian fluid under oscillatory shear test: a direct numerical simulation

Hashemi, M. R ; Sharif University of Technology

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  1. Type of Document: Article
  2. DOI: 10.1063/1.5009360
  3. Abstract:
  4. Adirect numerical simulation approach is used to investigate the effective non-linear viscoelastic stress response of non-gap-spanning magnetic chains suspended in a Newtonian fluid. The suspension is confined in a channel and the suspended clusters are formed under the influence of a constant external magnetic field. Large amplitude oscillatory shear (LAOS) tests are conducted to study the non-linear rheology of the system. The effect of inertia on the intensity of non-linearities is discussed for both magnetic and non-magnetic cases. By conducting magnetic sweep tests, the intensity and quality of the non-linear stress response are studied as a function of the strength of the external magnetic field. The Chebyshev expansion of the stress response is used to quantify the non-linear intra-cycle behaviour of the suspension. It is demonstrated that the system shows a strain-softening behaviour while the variation of the dynamic viscosity is highly sensitive to the external magnetic field. In a series of strain sweep tests, the overall non-linear viscoelastic behaviour of the system is also investigated for both a constant frequency and a constant strain-rate amplitude. It is shown that the intra-cycle behaviour of the system is different from its inter-cycle behaviour under LAOS tests
  5. Keywords:
  6. Chains ; Magnetic fields ; Newtonian liquids ; Numerical models ; Strain rate ; Testing ; Viscoelasticity ; Chebyshev expansion ; Constant strain rate ; Dynamic viscosities ; External magnetic field ; Large amplitude oscillatory shear ; Numerical simulation approaches ; Strain softening behaviour ; Strain sweep tests ; Magnetism
  7. Source: Physics of Fluids ; Volume 29, Issue 10 , 2017 ; 10706631 (ISSN)
  8. URL: https://aip.scitation.org/doi/abs/10.1063/1.5009360?journalCode=phf