Axial Stress in Elongational Flow of Fiber Suspension

Kizior, T. E.; Seyer, F. A.

doi:10.1122/1.549336

Cited by 35 publications

(11 citation statements)

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“…Interesting results have also been obtained, however, in an extensional flow which, as remarked earlier, cannot be described by using the conventional viscometric functions. One experiment that has brought out the non-Newtonian character of suspensions in extensional flow was peI formed by three groups: Weinberger and Goddard ( 1'374), Mewis and Metzner (1974), and Kizior and Seyer (1974) (1971).…”

Section: Extensional Flowmentioning

confidence: 99%

The rheological properties of suspensions of rigid particles

1976

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Experimental and theoretical work on the rheological properties of suspensions are reviewed. Attention is focused on systems consisting of rigid, neutrally buoyant particles suspended in Newtonian fluids; no restrictions, however, are placed on the concentration of the particles or on the forces acting in the suspension. The assumption that an effective viscosity depending solely on the volume fraction of the particles suffices to describe the rheology of suspensions is examined and shown to be inadequate. Indeed, the experimental evidence strongly supports the view that suspensions behave macroscopically as non-Newtonian fluids whose rheological properties are influenced by a large number of factors; these factors are listed. The various theories that have been put forward to explain the flow of suspensions are discussed, with particular emphasis being placed on the nature of the approximations made, so that purely empirical formulas can be clearly separated from those having a theoretical basis. Suggestions for future work, both theoretical and experimental, are provided. D. J. JEFFREY and ANDREAS ACRIVOS Department of Chemical EngineeringStanford University Stanford, California 94305 SCOPEA well-known and long-standing problem in fluid mechanics has been the calculation of the effective viscosity of a suspension. In recent years it has become clear that many of the complex phenomena associated with a flowing suspension cannot be explained by using a classical Newtonian description of a fluid with an effective viscosity. Thus, suspensions have to be treated as nowNewtonian fluids whose rheological (flow) properties are influenced by a large number of variables. This review presents some of the reasons why such non-Newtonian behavior occurs and describes the variables that must be included in any proposed theory for such behavior. The discussion is restricted to suspensions of rigid, neutrally buoyant particles in Newtonian fluids and thereby excludes emulsions, reinforced plastics, etc., but otherwise no restrictions are placed on the scope of the review. CONCLUSIONS AND SIGNIFICANCEThe volume fraction of the particles in a suspension (volume occupied by particles per unit volume of suspension) has often been assumed to be the only variable that influences the observed rheological properties of the suspension. Experimental evidence is presented to show that this is incorrect and that other factors, such as the shape and size distribution of the particles, the presence of electrical charges, and the type of flow being experienced must be considered. It readily follows then that no formula can exist that will give the effective viscosity or other flow properties solely as a function of the volume fraction of the particles. Of the many expressions that have been advanced for predicting the dependence of the flow properties on the factors referred to above, some are empirical while others rest on sound theoretical foundations. Successful empirical formulas generally contain one or more adjustable parameters which m...

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Section: Extensional Flowmentioning

confidence: 99%

The rheological properties of suspensions of rigid particles

1976

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“…Recent measurements of this kind include those reported by Ch � n et al ), Spearot & Metzner (1972, Acierno et al (1974), Mewis & Metzner (1974), Weinberger & Goddard (1974, and Moore & Pearson (1975). The convergent die-entry flows studied by Cogswell (1969) involve extension rates of the order of 1 to 100 sec-I let-thrust experiments involve extension rates of the order of 10 to 103 sec-I (Metzner & Metzner 1970, Kizior & Seyer 1974, Oliver & Bragg 1974. Rates in the range 100 to 800 sec -I are obtained in the triple jet apparatus proposed by Oliver & Bragg (1974).…”

Section: A Strong Flow: Steady Extensionmentioning

confidence: 93%

Steady Non-Viscometric Flows of Viscoelastic Liquids

Pipkin¹,

Tanner²

1977

Annu. Rev. Fluid Mech.

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“…Equations (17) and (19) are the evolution equations governing the dynamics of the fibers. The boundary conditions for these equations are,…”

Section: B Cell Model For the Drag Coefficient Of Fibers In A Non-nementioning

confidence: 99%

“…Past efforts have been made to evaluate the viscosity of a dilute Newtonian suspension of orientable particles [3,4,17,19,23]. Nevertheless, an exact form of equation of change describing the orientational state of fibers in formulating the Theological model of fibrous suspensions is unavailable.…”

Section: Introductionmentioning

confidence: 99%

A constitutive approach for studying concentrated suspensions of rigid fibers in a non ‐ Newtonian Ellis fluid

Wang

Cheau

1991

Journal of the Chinese Institute of Engineers

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A constitutive model for a semi-concentrated suspension of rigid fibers in a non-Newtonian fluid is derived in the present study. This work is extended from a previous work by Dinh and Armstrong which counted rigid fibers suspended in a Newtonian fluid. To investigate the effect of the sheardependent suspending fluid on the shear viscosity of suspension, the Ellis fluid is assumed to model such a non-linear matrix. It is shown that the present derivation, via a cell model, gives an analytic form to calculate the drag coefficient of fibers and to illustrate the influence of material parameters of matrix fluid. The resulting equation gives the bulk stress in terms of an integral over a fourth-order orientation vector, e, similar to the expression of Doi and Edwards for dense macromolecular fluid. For the purpose of evaluation, the present model attempts to predict the rheological behavior in the inception of flow, steady simple shear flow and stress-growth experiments.

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Axial Stress in Elongational Flow of Fiber Suspension

Cited by 35 publications

References 0 publications

The rheological properties of suspensions of rigid particles

The rheological properties of suspensions of rigid particles

Steady Non-Viscometric Flows of Viscoelastic Liquids

A constitutive approach for studying concentrated suspensions of rigid fibers in a non ‐ Newtonian Ellis fluid

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