A computer simulation of complex flows of fibre suspensions

Baloch, A.; Webster, M.F.

doi:10.1016/0045-7930(94)00023-r

Cited by 25 publications

(37 citation statements)

References 22 publications

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“…This result obtained with both the fibre-aligned approach and with the solution based on the orientation tensors is in qualitative agreement with previous experimental and numerical studies dealing with axisymmetric circular contractions (Lipscomb et al, 1988;Chiba et al, 1990;Baloch and Webster, 1995). Furthermore, the examination of the vortex at the salient corner shows that the predicted size increases with increasing Λ; i.e.…”

Section: Resultssupporting

confidence: 91%

“…It is clear that for a fixed fibre parameter; Λ = 5 or Λ = 20, the vortex at the corner is substantially reduced when the Reynolds number increases. This result is in accordance with the findings of previous studies using the fibre-aligned assumption (Lipscomb et al, 1988;Baloch and Webster, 1995). In the case of a creeping flow Re = 0, the addition of fibres, Λ = 5 and Λ = 20 leads to a sharp increase in the vortex size, with values of χ* equal to 1.9 and 3.8, respectively.…”

Section: Streamlinessupporting

confidence: 94%

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Numerical Modelling of the Flow of Fibre Suspensions through a Planar Contraction

Azaiez

Guénette

2002

Can J Chem Eng

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Fibre reinforced composites have gained increasing technological importance due to their versatility, which lends them to a wide range of applications. These composites are useful because they include a reinforcing phase in which high tensile strengths can be reached, and a matrix that allows one to hold the reinforcement and to transfer the applied stress to it. It is a well-known fact that such materials can have excellent mechanical, thermal, and electrical properties that make them widely used in industry. During the manufacturing process, fibres adopt a preferential orientation that can vary significantly across the geometry. Once the suspension is cooled or cured to make a solid composite, the fibre orientation becomes a key feature of the final product since it affects the elastic modulus, the thermal and electrical conductivities, and the strength of the composite material (Pipes et al., 1982;Agari et al., 1991).With the increase in composite materials usage, interest in the rheology and processing of fibre suspensions has increased significantly. This growing interest stems from the need to model the flow of fibres as accurately as possible in order to design and control manufacturing processes that generate favourable fibre orientations states, which will ultimately lead to the best mechanical and thermal properties of the composite. The rheological behaviour of a suspension of rigid particles has been the subject of a considerable amount of research (Stover et al., 1992;Becraft and Metzner, 1992;Bay and Tucker, 1992;Ramazani et al., 1997). Most of the existing theoretical work is based on the early studies of Jeffery (1923) and Batchelor (1971).Continuum models are often used to describe the orientation of fib r e s in a flo w. These models are hyperbolic in nature, and often lead to sharp b o u n d a ry layers and singularities even for simple flow geometries. In order to avoid this limitation, many authors adopted a simplifying approach known as the fibre-aligned assumption to study fibre suspension flows in various contraction and expansion geometries (see for example Lipscomb et al., 1988;Chiba et al., 1990; Baloch and We b s t e r, 1995). In this approach, it is assumed that the fibre is completely aligned with the streamlines, and therefore one has to solve only for the velocity field from which the fibre orientation can be deduced. The same approach has also been used by Rallison and Keiller (1993) to investigate

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Section: Resultssupporting

confidence: 91%

Section: Streamlinessupporting

confidence: 94%

Numerical Modelling of the Flow of Fibre Suspensions through a Planar Contraction

Azaiez

Guénette

2002

Can J Chem Eng

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“…When the aligned-fiber approximation, Equation (8), is made, the problem may be formulated using velocity and pressure (or streamfunction and vorticity) as the only primary variables. Solutions using this approach were developed by Evans (1975b), Libscomb et al (1988), Chiba et al (1990), and Baloch and Webster (1995). The aligned-fiber approximation has proved quite successful in modeling contraction flow.…”

Section: Finite Element Formulation Previous Numerical Solutionsmentioning

confidence: 99%

“…The numerical predictions of Lipscomb et al for the vortex length L v and the streamline pattern, using the aligned-fiber approximation, showed excellent agreement with the experiments. Chiba et al (1990) and Baloch and Webster (1995) extended these calculations to higher Reynolds numbers, still retaining the aligned-fiber approximation, and showed that the vortex strength decreases somewhat with Reynolds number, but becomes independent of N p when R e ≥ 20. Azaiez et al (1997) used a rheological model that could include shear thinning and matrix viscoelasticity as well as the effect of fibers, and studied a 4:1 planar contraction with planar fiber orientation.…”

Section: Axisymmetric Contractionmentioning

confidence: 99%

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Fiber Suspensions in Complex Geometries: Flow/Orientation Coupling

2002

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Simulation of particle settling in rotating and non-rotating flows of non-Newtonian fluids

Rameshwaran

Townsend

Webster

1998

Int. J. Numer. Meth. Fluids

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In this paper finite element solutions are presented for the flow of Newtonian and non-Newtonian fluids around a sphere falling along the centreline of a cylindrical tube. Both rotating and stationary tube scenarios are considered. Calculations are reported for three different inelastic constitutive models that manifest shear-thinning, extension-thickening and their combination. The influence of inertia and these various forms of viscous response are examined for their influence upon the drag on the settling particle and the structure of the flow. Simulations are performed by employing a semi-implicit time marching Taylor-Galerkin/pressure-correction finite element algorithm, a fractional-staged scheme of secondorder accuracy. KEY WORDS Finite elements, Taylor-Galerkin/pressure correction, particle settling, drag, rotating and non-rotating flows, inelastic non-Newtonian fluids.

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A computer simulation of complex flows of fibre suspensions

Cited by 25 publications

References 22 publications

Numerical Modelling of the Flow of Fibre Suspensions through a Planar Contraction

Numerical Modelling of the Flow of Fibre Suspensions through a Planar Contraction

Fiber Suspensions in Complex Geometries: Flow/Orientation Coupling

Simulation of particle settling in rotating and non-rotating flows of non-Newtonian fluids

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