Powered by OpenAIRE graph
Found an issue? Give us feedback
addClaim

Internal viscosity dumbbell model with a Gaussian approximation

Authors: Jay D. Schieber;

Internal viscosity dumbbell model with a Gaussian approximation

Abstract

A noninertial Hookean dumbbell with internal viscosity (or internal friction) is studied in transient and steady shear flows by use of a Gaussian closure on the second moment equation of the configuration of the dumbbell. The model predicts shear thinning for the viscosity and first normal stress coefficients for all values of the relative internal viscosity parameter ε. A second Newtonian region is observed for the viscosity. Qualitative, but not quantitative, agreement is found with optically determined orientation angles of polymer coils in steady shear flows for dilute polymer solutions. The model greatly overestimates the amount of relative stretching of the polymer coil in steady shear flow. In startup flows, large, but finite, values of ε show shear stress overshoot at high shear rates, and oscillatory behavior at the highest shear rates studied. Transient negative values of the first normal stress difference are also predicted. The maximum in stress is attained at much lower values of strain than for the predictions at small ε. The oscillations are shown to be caused primarily by oscillations in the orientation of the polymer coil, rather than by oscillations in the size of the polymer coil. Instantaneous jumps in the shear stress at t=0 are observed in agreement with Manke and Williams. Cessation of shear flows shows a jump in stress in agreement with data on xanthan gum. The decay upon cessation is nonexponential, but does follow the Lodge–Meissner relation. The width of the polymer coil is predicted to go through a maximum during this decay. Also, the addition of internal viscosity to the dumbbell satisfactorally gives a positive asymptotic value for η′−ηs (in-phase complex viscosity minus solvent contribution) in small amplitude oscillatory shear flow.

Related Organizations
  • BIP!
    Impact byBIP!
    selected citations
    These citations are derived from selected sources.
    This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
    22
    popularity
    This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
    Top 10%
    influence
    This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
    Top 10%
    impulse
    This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
    Average
Powered by OpenAIRE graph
Found an issue? Give us feedback
selected citations
These citations are derived from selected sources.
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
22
Top 10%
Top 10%
Average
Upload OA version
Are you the author of this publication? Upload your Open Access version to Zenodo!
It’s fast and easy, just two clicks!