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Journal articles on the topic 'Fibre suspensions'

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Author: Grafiati

Published: 4 June 2021

Last updated: 20 February 2023

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1

Redlinger-Pohn, Jakob D., Melanie Mayr, Gregor Schaub, David Gruber, and Stefan Radl. "Fines mobility and distribution in streaming fibre networks: experimental evidence and numerical modeling." Cellulose 27, no. 16 (September 23, 2020): 9663–82. http://dx.doi.org/10.1007/s10570-020-03443-9.

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AbstractThe motion of flocculated fibres in a streaming suspension is governed by the balance of the network strength and hydrodynamic forces. With increasing flow rate through a channel, (1) the network initially occupying all space, (2) is then compressed to the centre, and (3) ultimately dispersed. This classical view neglects fibres-fines: we find that the distribution of these small particles differs in streaming suspensions. While it is known that fibre-fines can escape the fibre network, we find that the distribution of fibre-fines is non-homogenous in the network during compression: fibre-fines can be caged and retarded in the streaming fibre network. Hence, the amount of fibre-fines is reduced outside of a fibre network and enriched at the network’s interface. Aiming on selectively removing fibre-fines from a streaming network by suction, we identify a reduction of the fines removal rate. That documents a hindered mobility of fibre-fines when moving through the network of fibres. Additionally, we found evidence, that the mobility of fibre-fines is dependent on the fibre-fines quality, and is higher for fibrillar fines. Consequently, we suggest that the quality of fibre-fines removed from the suspension can be controlled with the flow regime in the channel. Finally, we present a phenomenological model to compute the length dependent fibre distribution in an arbitary geometry. For a fibre suspension channel flow we are able to predict a length-dependent fibre segregation near the channel’s centre. The erosion of a plug of long fibres was however underestimated by our model. Interestingly, our model with parameters fitted to streaming fibre suspension qualitatively agreed with the motion of micro-fibrillated cellulose. This gives hope that devices for handling flocculated fibre suspensions can be designed in the future with greater confidence.

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2

Manikantan, Harishankar, Lei Li, Saverio E. Spagnolie, and David Saintillan. "The instability of a sedimenting suspension of weakly flexible fibres." Journal of Fluid Mechanics 756 (September 9, 2014): 935–64. http://dx.doi.org/10.1017/jfm.2014.482.

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AbstractSuspensions of sedimenting slender fibres in a viscous fluid are known to be unstable to fluctuations of concentration. In this paper we develop a theory for the role of fibre flexibility in sedimenting suspensions in the asymptotic regime of weakly flexible bodies (large elasto-gravitation number). Unlike the behaviour of straight fibres, individual flexible filaments rotate as they sediment, leading to an anisotropic base state of fibre orientations in an otherwise homogeneous suspension. A mean-field theory is derived to describe the evolution of fibre concentration and orientation fields, and we explore the stability of the base state to perturbations of fibre concentration. We show that fibre flexibility affects suspension stability in two distinct and competing ways: the anisotropy of the base state renders the suspension more unstable to perturbations, while individual particle self-rotation acts to prevent clustering and stabilizes the suspension. In the presence of thermal noise, the dominant effect depends critically upon the relative scales of flexible fibre self-rotation compared to rotational Brownian motion.

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3

MACKAPLOW, MICHAEL B., and ERIC S. G. SHAQFEH. "A numerical study of the sedimentation of fibre suspensions." Journal of Fluid Mechanics 376 (December 10, 1998): 149–82. http://dx.doi.org/10.1017/s0022112098002663.

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The sedimentation of fibre suspensions at low Reynolds number is studied using two different, but complementary, numerical simulation methods: (1) Monte Carlo simulations, which consider interparticle hydrodynamic interactions at all orders within the slender-body theory approximation (Mackaplow & Shaqfeh 1996), and (ii) dynamic simulations, which consider point–particle interactions and are accurate for suspension concentrations of nl3=1, where n and l are the number density and characteristic half-length of the fibres, respectively. For homogeneous, isotropic suspensions, the Monte Carlo simulations show that the hindrance of the mean sedimentation speed is linear in particle concentration up to at least nl3=7. The speed is well predicted by a new dilute theory that includes the effect of two-body interactions. Our dynamic simulations of dilute suspensions, however, show that interfibre hydrodynamic interactions cause the spatial and orientational distributions to become inhomogeneous and anisotropic. Most of the fibres migrate into narrow streamers aligned in the direction of gravity. This drives a downward convective flow within the streamers which serves to increase the mean fibre sedimentation speed. A steady-state orientation distribution develops which strongly favours fibre alignment with gravity. Although the distribution reaches a steady state, individual fibres continue to rotate in a manner that can be qualitatively described as a flipping between the two orientations aligned with gravity. The simulation results are in good agreement with published experimental data.

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4

Sridang, P. Choksuchart, M. Heran, and A. Grasmick. "Influence of module configuration and hydrodynamics in water clarification by immersed membrane systems." Water Science and Technology 51, no. 6-7 (March 1, 2005): 135–42. http://dx.doi.org/10.2166/wst.2005.0631.

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Different immersed membrane systems were compared according to the module configuration. Filtering concentrated aqueous suspensions under constant permeate flux, the hydraulic performances of the systems were evaluated and compared through parameters such as critical permeate flux notion and trans-membrane pressure variation rates. Operational variables were membrane size and module fibre density, aeration inside or outside the fibre network, suspension concentration and physico-chemical conditioning. When using hollow fibres including a possible air injection inside the fibre network, results pointed out the positive role of the aeration on the fouling control. But too high a fibre density did not allow an optimal control when the aqueous suspension was very concentrated. On the other hand, when working with capillary membranes showing sufficient space between fibres, the major parameters were the transversal suspension flow circulation through the fibre network and the FeCl3 conditioning of the suspension. Experimental results show a possible working at a 0.07 m3.m2.h1 permeate flow rate under low TMP evolutions, 0.02 Pa/s, even if the filtration was operated under high concentrated suspension, 5 kgSS/m3.

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5

Nguyen, Hung Quoc, and Canh-Dung Tran. "Simulation of non-dilute fibre suspensions using RBF-based macro–micro multiscale method." Korea-Australia Rheology Journal 34, no. 1 (February 2022): 1–15. http://dx.doi.org/10.1007/s13367-022-00022-1.

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AbstractThe multiscale stochastic simulation method based on the marriage of the Brownian Configuration Field (BCF) and the Radial Basis Function mesh-free approximation for dilute fibre suspensions by our group, is further developed to simulate non-dilute fibre suspensions. For the present approach, the macro and micro processes proceeded at each time step are linked to each other by a fibre contributed stress formula associated with the used kinetic model. Due to the feature of non-dilute fibre suspensions, the interaction between fibres is introduced into the evolution equation to determine fibre configurations using the BCF method. The fibre stresses are then determined based on the fibre configuration fields using the Phan–Thien–Graham model. The efficiency of the simulation method is demonstrated by the analysis of the two challenging problems, the axisymmetric contraction and expansion flows, for a range of the fibre concentration from semi-dilute to concentrated regimes. Results evidenced by numerical experiments show that the present method would be potential in analysing and simulating various suspensions in food and medical industries.

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6

Feist, Markus, Hermann Nirschl, Jörg Wagner, Georg Hirsch, and Samuel Schabel. "Experimental Results for the Settling Behaviour of Particle-Fiber Mixtures." Physical Separation in Science and Engineering 2007 (February 11, 2007): 1–6. http://dx.doi.org/10.1155/2007/91740.

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Sedimentation of organic fibres and inorganic particles can be observed in several industrial applications. Fibres are involved not only in wastewater treatment but also in other separation applications. In the paper industry, the separation of inorganic filler and coating particles from short cellulose fibres is still a challenge in the recycling process. During that process, particles have to be removed to obtain a purified fibre suspension. These fibres can be used again to produce new paper. With the currently applied techniques, like screening and flotation, the efficiency of short fibre separation is very poor. Moreover, also separation by sedimentation fails due to similar settling velocities of heavy-small particles and the light and larger fibres. This paper concentrates on the sedimentation of organic fibres and inorganic particles in water. The investigated suspensions are made by resolving two different and specially produced papers a coated and an uncoated one, as well as the single components used for its production. We observe a different sedimentation behaviour according to the concentration of fibres and particles in the suspension and the pH-value of it. The main result is that, according to the fibre rate, the sedimentation behaviour is particle dominant or fibre dominant.

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7

Ahmed, Shams Forruque. "Theoretical Model Development for Energy Motion of Dusty Turbulent Flow of Fibre Suspensions in a Rotational Frame." Complexity 2022 (April 12, 2022): 1–11. http://dx.doi.org/10.1155/2022/8705997.

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Fibre suspension has garnered considerable attention in turbulent flows that are used in many industries. Solid particles, such as dust particles, notably affect the turbulent flow field in a rotational frame. In assessing their impacts, the dusty turbulent flow for fibre suspensions needs to be studied in a frame of rotation that can be substantially applied in many industries. This study, therefore, aims to build a theoretical model for the energy motion of dusty turbulent flow of fibre suspensions in a rotational frame. The turbulence momentum equation was considered to formulate the model in presence of dusty fluid rotating flow of fibre suspensions. The newly derived equation was derived in second-order correlation tensors Fi,j, Wi,j, Gi,j, Si,j, Xi,j, Yi,j, Qi,j, and Ri,j at any two points in the flow domain, where the tensors were expressed as space, time, and distance functions. The developed model is a considerable improvement because it takes into account all of the potential influential parameters that could affect the motion of turbulent energy, such as dust particles, suspending particles (fibres), and rotating frame. However, the impact of these parameters on turbulence energy motion must be evaluated in order to assess the performance of turbulence systems utilized in a variety of industries, such as paper manufacturing. The present theoretical development will contribute to open up experimental and numerical research opportunities for the advancement of the industry, science, and technology.

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8

Mackaplow, Michael B., and Eric S. G. Shaqfeh. "A numerical study of the rheological properties of suspensions of rigid, non-Brownian fibres." Journal of Fluid Mechanics 329 (December 25, 1996): 155–86. http://dx.doi.org/10.1017/s0022112096008889.

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Using techniques developed in our previous publication (Mackaplow et al. 1994), we complete a comprehensive set of numerical simulations of the volume-averaged stress tensor in a suspension of rigid, non-Brownian slender fibres at zero Reynolds number. In our problem formulation, we use slender-body theory to develop a set of integral equations to describe the interfibre hydrodynamic interactions at all orders. These integral equations are solved for a large number of interacting fibres in a periodically extended box. The simulations thus developed are an accurate representation of the suspensions at concentrations up to and including the semidilute regime. Thus, large changes in the suspensions properties can be obtained. The Theological properties of suspensions with concentrations ranging from the dilute regime, through the dilute/semi-dilute transition, and into the semi-dilute regime, are surprisingly well predicted by a dilute theory that takes into account two-body interactions. The accuracy of our simulations is verified by their ability to reproduce published suspension extensional and shear viscosity data for a variety of fibre aspect ratios and orientation distributions, as well as a wide range of suspension concentrations.

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9

Xiao-Ke, Ku, and Lin Jian-Zhong. "Orientational Distribution of Fibres in Sheared Fibre Suspensions." Chinese Physics Letters 24, no. 6 (June 2007): 1622–25. http://dx.doi.org/10.1088/0256-307x/24/6/053.

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10

WU, JINGSHU, and CYRUS K. AIDUN. "A numerical study of the effect of fibre stiffness on the rheology of sheared flexible fibre suspensions." Journal of Fluid Mechanics 662 (September 27, 2010): 123–33. http://dx.doi.org/10.1017/s0022112010003885.

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A recently developed particle-level numerical method is used to simulate flexible fibre suspensions in Newtonian simple shear flow. In this method, the flow is computed on a fixed regular ‘lattice’ using the lattice Boltzmann method, where each solid particle, or fibre in this case, is mapped onto a Lagrangian frame moving continuously through the domain. The motion and orientation of the fibre are obtained from Newtonian dynamics equations. The effect of fibre stiffness on the rheology of flexible fibre suspensions is investigated and a relation for the relative viscosity is obtained. We show that fibre stiffness (bending ratio, BR) has a strong impact on rheology in the range BR < 3. The relative viscosity increases significantly as BR decreases. These results show that the primary normal stress difference has a minimum value at BR ~ 1. The primary normal stress difference for slightly deformable fibres reaches a minimum and increases significantly as BR decreases below one. The results are explained based on Batchelor's relation for non-Brownian suspensions.

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11

Schiek, Richard L., and Eric S. G. Shaqfeh. "A nonlocal theory for stress in bound, Brownian suspensions of slender, rigid fibres." Journal of Fluid Mechanics 296 (August 10, 1995): 271–324. http://dx.doi.org/10.1017/s0022112095002138.

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A nonlocal theory for stress in bound suspensions of rigid, slender fibres is developed and used to predict the rheology of dilute, rigid polymer suspensions when confined to capillaries or fine porous media. Because the theory is nonlocal, we describe transport in a fibre suspension where the velocity and concentration fields change rapidly on the fibre's characteristic length. Such rapid changes occur in a rigidly bound domain because suspended particles are sterically excluded from configurations near the boundaries. A rigorous no-flux condition resulting from the presence of solid boundaries around the suspension is included in our nonlocal stress theory and naturally gives rise to concentration gradients that scale on the length of the particle. Brownian motion of the rigid fibres is included within the nonlocal stress through a Fokker–Planck description of the fibres’ probability density function where gradients of this function are proportional to Brownian forces and torques exerted on the suspended fibres. This governing Fokker–Planck probability density equation couples the fluid flow and the nonlocal stress resulting in a nonlinear set of integral-differential equations for fluid stress, fluid velocity and fibre probability density. Using the method of averaged equations (Hinch 1977) and slender-body theory (Batchelor 1970), the system of equations is solved for a dilute suspension of rigid fibres experiencing flow and strong Brownian motion while confined to a gap of the same order in size as the fibre's intrinsic length. The full solution of this problem, as the fluid in the gap undergoes either simple shear or pressure-driven flow, is solved self-consistently yielding average fluid velocity, shear and normal stress profiles within the gap as well as the probability density function for the fibres’ position and orientation. From these results we calculate concentration profiles, effective viscosities and slip velocities and compare them to experimental data.

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12

Petrie, Christopher J. S. "The rheology of fibre suspensions." Journal of Non-Newtonian Fluid Mechanics 87, no. 2-3 (November 1999): 369–402. http://dx.doi.org/10.1016/s0377-0257(99)00069-5.

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13

Zirnsak, M. A., D. U. Hur, and D. V. Boger. "Normal stresses in fibre suspensions." Journal of Non-Newtonian Fluid Mechanics 54 (August 1994): 153–93. http://dx.doi.org/10.1016/0377-0257(94)80020-0.

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14

Yamanoi, Mikio, and João M. Maia. "Analysis of rheological properties of fibre suspensions in a Newtonian fluid by direct fibre simulation. Part1: Rigid fibre suspensions." Journal of Non-Newtonian Fluid Mechanics 165, no. 19-20 (October 2010): 1055–63. http://dx.doi.org/10.1016/j.jnnfm.2010.05.003.

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15

AZAIEZ, J. "Linear stability of free shear flows of fibre suspensions." Journal of Fluid Mechanics 404 (February 10, 2000): 179–209. http://dx.doi.org/10.1017/s002211209900717x.

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A linear stability analysis of the mixing layer in the presence of fibre additives is presented. Using a formulation based on moments of the probability distribution function to determine the particle orientation, we extend the classical linear stability theory and derive a modified Orr–Sommerfeld equation. It is found that, for large Reynolds numbers, the flow instability is governed by two parameters: a dimensionless group H, analogous to a reciprocal Reynolds number representing the importance of inertial forces versus viscous forces associated with the anisotropic elongational viscosity of the suspension; and a coefficient CI that accounts for inter-particle hydrodynamic interactions. A parametric study reveals that both parameters can induce an important attenuation of the flow instability. Furthermore, we show that the stabilizing effects arise from the orientation diffusion due to hydrodynamic interactions, and not from the anisotropy induced by the presence of fibres in the flow, as speculated before. The examination of profile contours of different perturbation terms and the analysis of the rate of production of enstrophy show clearly that the main factor behind the reduction of the flow instability is associated with the fibre shear stress disturbance. This disturbance acts as a dissipative term as the fibres, due to the orientational diffusivity arising from hydrodynamic interactions, deviate from the fully aligned anisotropic orientation. On the other hand, fibre normal stresses act as a destabilizing factor and are important only in the absence of hydrodynamic interactions.

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16

Hadraba, Hynek, Zdeněk Chlup, Daniel Drdlík, and Jaroslav Cihlář. "Microfibres Containing Laminates Prepared by EPD: Kinetics of Co-Deposition." Key Engineering Materials 654 (July 2015): 65–69. http://dx.doi.org/10.4028/www.scientific.net/kem.654.65.

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The aim of this work was preparation of alumina laminates and fibre reinforced alumina containing zirconia micro-fibres inside the inter-layer interface. Electrophoretic deposition was performed from concentrated isopropanolic suspensions stabilised by monochloracetic acid containing mixture of alumina powder and certain amount of zirconia micro-fibres. A method for in-situ monitoring of deposited amount of mixture of particles and fibres mass was applied to control deposition kinetics. Two different approaches for composite deposition were applied: pre-milling of powders mixture prior electrophoretic deposition and milling of suspension containing stabilization aid. Applying the optimised procedure the alumina laminates were prepared consisting of fibres in the interlayer boundary affected dramatically fracture response of these materials.

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17

Björkman, Ulf. "Floc dynamics in flowing fibre suspensions." Nordic Pulp & Paper Research Journal 20, no. 2 (May 1, 2005): 247–52. http://dx.doi.org/10.3183/npprj-2005-20-02-p247-252.

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18

Sundararajakumar, R. R., and Donald L. Koch. "Electrical conductivity of isotropic fibre suspensions." Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences 455, no. 1985 (May 8, 1999): 1923–30. http://dx.doi.org/10.1098/rspa.1999.0386.

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19

Fan, Xijun, N. Phan-Thien, and Rong Zheng. "A direct simulation of fibre suspensions." Journal of Non-Newtonian Fluid Mechanics 74, no. 1-3 (January 1998): 113–35. http://dx.doi.org/10.1016/s0377-0257(97)00050-5.

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20

Grigelmo-Miguel, N., A. Ibarz-Ribas, and O. Martı́n-Belloso. "Rheology of peach dietary fibre suspensions." Journal of Food Engineering 39, no. 1 (January 1999): 91–99. http://dx.doi.org/10.1016/s0260-8774(98)00151-4.

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21

Bennington, C. P. J., R. J. Kerekes, and J. R. Grace. "The yield stress of fibre suspensions." Canadian Journal of Chemical Engineering 68, no. 5 (October 1990): 748–57. http://dx.doi.org/10.1002/cjce.5450680503.

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22

Yamanoi, Mikio, João Maia, and Tae-soo Kwak. "Analysis of rheological properties of fibre suspensions in a Newtonian fluid by direct fibre simulation. Part 2: Flexible fibre suspensions." Journal of Non-Newtonian Fluid Mechanics 165, no. 19-20 (October 2010): 1064–71. http://dx.doi.org/10.1016/j.jnnfm.2010.05.004.

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23

McComb, W. D., and K. T. J. Chan. "Laser-Doppler anemometer measurements of turbulent structure in drag-reducing fibre suspensions." Journal of Fluid Mechanics 152 (March 1985): 455–78. http://dx.doi.org/10.1017/s0022112085000787.

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A laser-Doppler anemometer (LDA) was used to measure turbulent velocities in drag-reducing fibre suspensions. Measurements of streamwise velocities (and, in one case, the circumferential velocity as well) were made in flow through a straight pipe at x/d = 190, and at Reynolds numbers in the range 1.4 × 104–5.3 × 104. The fibres used were chrysotile asbestos of high aspect ratio (∼ 106), at a concentration of 300 w.p.p.m. They were dispersed in an aqueous solution of a surfactant (0.5% by weight Aerosol OT). In some experiments, the fibre suspensions were supplemented by a drag-reducing polymer (Separan AP30) at a concentration of 150 w.p.p.m. A complete experiment involved passing a quantity of fibre suspension through the apparatus a number of times (at a given Reynolds number) and measuring the velocity distribution across the pipe during each pass. As the amount of drag reduction generally declined with the number of passes (i.e. due to fibre degradation), this provided a convenient way of varying the percentage drag reduction as an experimental parameter. Results were obtained for mean velocity and intensity profiles, autocorrelations, and one-dimensional energy spectra. The mean period of turbulent bursts was determined by measuring autocorrelations with short sampling times.At the lowest Reynolds number (Re = 1.4 × 104), drag reductions of about 70% were obtained during the first two passes. This was accompanied by a reduction in the streamwise intensity below the level obtained in the surfactant solution alone. (Note: The opposite behaviour is found in drag-reducing polymer solutions, where intensity levels are larger than those in the solvent alone.) A measurement of the r.m.s. circumferential velocity showed an increased level (relative to surfactant alone) during this part of the experiment. During further passes, there was a transition to ‘polymer-like’ behaviour, with increased streamwise intensity, which subsequently declined with pass number (and hence drag reduction) towards the result for surfactant alone. This effect had previously been found in preliminary experiments at Re = 9 × 103 (McComb & Chan 1979). Repetition of the experiment a Re = 1.4 × 104, with the addition of Separan AP30, confirmed the existence of this transition from ‘fibre-like’ to ‘polymer-like’ drag reduction. In this case, the drag reduction was smaller (at about 60%), but the mixed suspension was much more resistant to degradation, with transition occurring at the ninth pass. However, such behaviour was not found at higher Reynolds numbers (Re = 3.2 × 104 and 5.3 × 104), in fibre suspensions where increased streamwise intensities occurred, even at high levels of drag reduction (about 70%).Anomalous streamwise autocorrelations were found during ‘fibre-like’ drag reduction but in the ‘polymer-like’ regime they were very similar to those measured in polymer solution, and showed characteristically increased lengthscales. On the other hand, energy spectra were found to be anomalous in all cases and showed an energy deficit at lengthscales of the same order as the fibre length. Finally, mean bursting periods were found to be much increased, with the increases being about the same as those in polymer solutions at the same Reynolds number and percentage drag reduction.

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24

BUTLER, JASON E., and ERIC S. G. SHAQFEH. "Dynamic simulations of the inhomogeneous sedimentation of rigid fibres." Journal of Fluid Mechanics 468 (October 8, 2002): 205–37. http://dx.doi.org/10.1017/s0022112002001544.

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We have simulated the dynamics of suspensions of fibres sedimenting in the limit of zero Reynolds number. In these simulations, the dominant inter-particle force arises from hydrodynamic interactions between the rigid, non-Brownian fibres. The simulation algorithm uses slender-body theory to model the linear and rotational velocities of each fibre. To include far-field interactions between the fibres, the line distribution of force on each fibre is approximated by making a Legendre polynomial expansion of the disturbance velocity on the fibre, where only the first two terms of the expansion are retained in the calculation. Thus, the resulting linear force distribution can be specified completely by a centre-of-mass force, a couple, and a stresslet. Short-range interactions between particles are included using a lubrication approximation, and an infinite suspension is simulated by using periodic boundary conditions. Our numerical results confirm that the sedimentation of these non-spherical, orientable particles differs qualitatively from the sedimentation of spherical particles. The simulations demonstrate that an initially homogeneous, settling suspension develops clusters, or streamers, which are particle rich surrounded by clarified fluid. The instability which causes the heterogeneous structure arises solely from hydrodynamic interactions which couple the particle orientation and the sedimentation rate in particle clusters. Depending upon the concentration and aspect ratio, the formation of clusters of particles can enhance the sedimentation rate of the suspension to a value in excess of the maximum settling speed of an isolated particle. The suspension of fibres tends to orient with gravity during the sedimentation process. The average velocities and orientations, as well as their distributions, compare favourably with previous experimental measurements.

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25

Tonoli, G. H. D., E. Fuente, C. Monte, H. Savastano, F. A. Rocco Lahr, and A. Blanco. "Effect of fibre morphology on flocculation of fibre–cement suspensions." Cement and Concrete Research 39, no. 11 (November 2009): 1017–22. http://dx.doi.org/10.1016/j.cemconres.2009.07.010.

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26

Bekem, Aylin, and Ahmet Unal. "Polyamide 12/E-glass Fabric Composite Production with Dip-coating." MATEC Web of Conferences 188 (2018): 01022. http://dx.doi.org/10.1051/matecconf/201818801022.

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In this study PA12 was reinforced with E-glass woven fabric by dip-coating. PA12 powder and ethanol suspensions were prepared with ratios at 30, 40 and 50% of powder to obtain different fibre contents. Coated fabrics were laid-up and kept in oven at 60°C to evaporate ethanol. Then it was placed in a compression mould and pressed. Obtained laminates were subjected to tensile, bending and impact tests. Fractured surfaces were observed. It was found that mechanical properties were highest when 40% PA powder used in suspension with dip-coating with additional lamination. Fibre failure and fibre pull-out were observed on fractured surfaces.

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27

Hardacre, Allan K., Roger G. Lentle, Sia-Yen Yap, and John A. Monro. "Predicting the viscosity of digesta from the physical characteristics of particle suspensions using existing rheological models." Journal of The Royal Society Interface 15, no. 142 (May 2018): 20180092. http://dx.doi.org/10.1098/rsif.2018.0092.

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The measurement of the viscosity of digesta is complicated by settling and compositional changes that accompany digestion. The current work determined whether the apparent and relative viscosities ( η a and η r ) of digesta could be accurately determined from the actual and maximum solid volume fractions ( ϕ and ϕ max , respectively) using the Maron–Pierce equation. The rheological properties of digesta from the small intestine of six pigs were determined at a shear rate of 1 s −1 at 37°C. A series of suspensions of plant fibre in a Newtonian liquid (70% aqueous fructose) were made at viscosities similar to pig digesta by adjusting ϕ . The relationships between the apparent and relative viscosities ( η a and η r ) and the plant fibre properties; aspect ratio (AR) and ϕ and ϕ max were then determined for digesta and the suspensions. The ARs for the digesta and plant fibre particles were determined using image analysis of scanning electron micrographs and η a from rheometric flow curves at 37°C, ϕ from image analysis and gas pycnometry, and ϕ max from AR and suspension viscosity. The η r of pig digesta and the test suspensions calculated using the Maron–Pierce equation were, with the exception of two outliers, in proportion with η a determined using a rheometer, indicating that η r could be successfully predicted from the Maron–Pierce equation.

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28

Voinov, Nikolai, Anastasiya Bogatkova, Denis Zemtsov, Aleksandr Vititnev, and Roman Marchenko. "Sedimentation of refined cellulosic pulp fines in the suspension during physical agglomeration." BioResources 17, no. 3 (May 3, 2022): 3883–905. http://dx.doi.org/10.15376/biores.17.3.3883-3905.

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A physical coagulator of fines was employed to separate suspensions comprising refined sulphate cellulose and waste paper, where no reagents were required. The physical coagulator was a porous cylinder with a rotating disk placed in its cavity. Using the MorFi Neo fibre analyser and the Hitachi SU 3500 digital microscope, a dispersed size distribution of well-developed fines in a suspension derived from softwood and hardwood pulp was obtained. The kinetics of fine sedimentation in the suspension was studied. The sedimentation rate of both individual agglomerates and a mass of them, as well as the magnitude of mass concentration in a cleared liquid, was determined. A relationship between the concentration of fines in the suspension and the structure of the pulp during their sedimentation was established. To intensify the fines sedimentation process, it was proposed to return a part of the sediment to the suspension passing into the physical coagulator. Process parameters for the sedimentation process and the construction of the sedimentation tank were obtained. The unit designed for collecting fines from the suspension is shown schematically. Use of this unit reduced the fibre sedimentation time, decreased the loads in wastewaters, and retained the consumer value of the pulp fibres.

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29

Hewitt, Duncan R., Daniel T. Paterson, Neil J. Balmforth, and D. Mark Martinez. "Dewatering of fibre suspensions by pressure filtration." Physics of Fluids 28, no. 6 (June 2016): 063304. http://dx.doi.org/10.1063/1.4952582.

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30

Carlsson, Allan, L. Daniel Söderberg, and Fredrik Lundell. "Fibre orientation measurements near a headbox wall." Nordic Pulp & Paper Research Journal 25, no. 2 (May 1, 2010): 204–12. http://dx.doi.org/10.3183/npprj-2010-25-02-p204-212.

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Abstract Experimental results on the fibre orientation in a laboratory scale headbox are reported. Images containing fibres in approximately 1 mm thick slices parallel to the wall were captured at different wall distances. A steerable filter was used to determine the orientation of bleached and unbeaten birch fibres, suspended in water, at different distances from one of the inclined walls of the headbox contraction. Due to optical limitations only dilute suspensions were studied. It is shown that the fibre orientation distribution varies with the distance from the wall. Sufficiently far upstream in the headbox a more anisotropic distribution is found closer to the wall.

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31

Moritz, Kirsten, and Eberhard Müller. "Electrophoretic Deposition of Ceramic Powders-Influence of Suspension and Processing Parameters." Key Engineering Materials 314 (July 2006): 51–56. http://dx.doi.org/10.4028/www.scientific.net/kem.314.51.

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The electrophoretic deposition (EPD) of AlN, Al2O3 and SiC, respectively, from ethanolic suspensions stabilised by suitable organic additives has been investigated. A main topic of this paper is the EPD in the direction of the gravitational force. Using an AlN suspension, the deposit weight depending on the experimental parameters was determined. The deposition was carried out under constant voltage or constant current conditions. Several factors influencing the effective electric field strength will be discussed. It could be shown that the conductivity of the suspension results mainly from the free ionic species. By EPD from the different suspensions, green bodies with monomodal pore size distributions were produced. The electrophoretic deposition of alumina from an ethanolic and from an aqueous suspension of the same composition led to similar results regarding the homogeneity of the particle packing in the deposits. The SiC suspension was also used for infiltrating woven carbon fibre mats by EPD in order to fabricate ceramic matrix composites.

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32

Panthapulakkal, S., and M. Sain. "Preparation and Characterization of Cellulose Nanofibril Films from Wood Fibre and Their Thermoplastic Polycarbonate Composites." International Journal of Polymer Science 2012 (2012): 1–6. http://dx.doi.org/10.1155/2012/381342.

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The aim of this study was to develop cellulose-nanofibril-film-reinforced polycarbonate composites by compression molding. Nano fibres were prepared from wood pulp fibres by mechanical defibrillation, and diameter distribution of the fibres produced was in the range of 1–100 nm. Nanofibre films were prepared from the nanofibre suspensions and were characterized in terms of strength properties, crystallinity, and thermal properties. Strength and modulus of the nano fibre films prepared were 240 MPa and 11 GPa, respectively. Thermal properties of the sheets demonstrated the suitability of processing fibre sheets at high temperature. Tensile properties of the films subjected to composite-processing conditions demonstrated the thermal stability of the fibre films during the compression molding process. Nanocomposites of different fibre loads were prepared by press-molding nano fibre sheets with different thickness in between polycarbonate sheet at 205°C under pressure. The tensile modulus and strength of the polycarbonate increased with the incorporation of the fibres. The strength of the thermoplastic increased 24% with 10% of the fibres and is increased up to 30% with 18% of the fibres. Tensile modulus of the polycarbonate demonstrated significant enhancement (about 100%).

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33

Winter, Armin, Benjamin Arminger, Stefan Veigel, Claudia Gusenbauer, Wolfgang Fischer, Melanie Mayr, Wolfgang Bauer, and Wolfgang Gindl-Altmutter. "Nanocellulose from fractionated sulfite wood pulp." Cellulose 27, no. 16 (September 15, 2020): 9325–36. http://dx.doi.org/10.1007/s10570-020-03428-8.

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AbstractFine fibre fractions in wood pulp may contribute to advantageous paper properties, but in some instances their removal from pulp may be beneficial to the production process of certain paper grades. In order to study the suitability of fine fibre fractions for the production of nanocellulose as an alternative use option, sulfite pulp was fractionated and homogenised, and cellulose nanopapers were produced. Characterisation revealed that fine fibre fractions were more easily homogenised than long fibres. Aqueous suspensions of nanocellulose produced from fines showed remarkably reduced viscosity compared to nanocellulose derived from long fibres. Nanopapers produced from all nanocellulose variants showed roughly similar mechanical performance. Only nanopaper produced from primary fines-derived nanocellulose deviated in that it showed a comparably high modulus of elasticity at a low strain at failure. Overall, fine fibre fractions separated from wood pulp were found to be highly suitable for nanocellulose production.

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34

Lin, Jianzhong, Xiaoyu Liang, and Shanliang Zhang. "Fibre orientation distribution in turbulent fibre suspensions flowing through an axisymmetric contraction." Canadian Journal of Chemical Engineering 89, no. 6 (April 21, 2011): 1416–25. http://dx.doi.org/10.1002/cjce.20490.

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35

Andersson, Sven R., Johan Ringnér, and Anders Rasmuson. "The network strength of non-flocculated fibre suspensions." Nordic Pulp & Paper Research Journal 14, no. 1 (January 1, 1999): 61–70. http://dx.doi.org/10.3183/npprj-1999-14-01-p061-070.

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36

Rasteiro, M. G., M. Panarra, I. Antunes, and G. Urbano. "Experimental Study of the Rheology of Fibre Suspensions." Chemie Ingenieur Technik 73, no. 6 (June 2001): 746. http://dx.doi.org/10.1002/1522-2640(200106)73:6<746::aid-cite7464444>3.0.co;2-t.

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37

Bennington, C. P. J., R. J. Kerekes, and J. R. Grace. "Motion of pulp fibre suspensions in rotary devices." Canadian Journal of Chemical Engineering 69, no. 1 (February 1991): 251–58. http://dx.doi.org/10.1002/cjce.5450690130.

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38

Pettersson, Johan, and Anders Rasmuson. "The Yield Stress of Gas/Liquid/Fibre Suspensions." Canadian Journal of Chemical Engineering 82, no. 6 (May 19, 2008): 1313–18. http://dx.doi.org/10.1002/cjce.5450820621.

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39

Ooi, Yong Wee, and Tamarapu Sridhar. "Resistance to uniaxial extensional flow of fibre suspensions." Rheologica Acta 43, no. 3 (May 1, 2004): 223–31. http://dx.doi.org/10.1007/s00397-003-0334-7.

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40

Derakhshandeh, B., R. J. Kerekes, S. G. Hatzikiriakos, and C. P. J. Bennington. "Rheology of pulp fibre suspensions: A critical review." Chemical Engineering Science 66, no. 15 (August 2011): 3460–70. http://dx.doi.org/10.1016/j.ces.2011.04.017.

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41

Snook, Braden, Levi M. Davidson, Jason E. Butler, Olivier Pouliquen, and Élisabeth Guazzelli. "Normal stress differences in suspensions of rigid fibres." Journal of Fluid Mechanics 758 (October 9, 2014): 486–507. http://dx.doi.org/10.1017/jfm.2014.541.

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AbstractMeasurements of normal stress differences are reported for suspensions of rigid, non-Brownian fibres for concentrations of $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}nL^2d=1.5\text {--}3$ and aspect ratios of $L/d=11\text {--}32$, where $n$ is the number of fibres per unit volume, $L$ is the fibre length and $d$ is the diameter. The first and second normal stress differences are determined experimentally from measuring the deformation in the free surface in a tilted trough and in a Weissenberg rheometer. Simulations are performed as well, and the hydrodynamic and contact contributions to the normal stresses are calculated. The experiments and simulations indicate that the second normal stress difference is negative and that its magnitude increases as the concentration is raised and the aspect ratio is lowered. The first normal stress difference is positive and its magnitude is approximately twice that of the second normal stress difference. Simulation results indicate that, for the concentrations and aspect ratios studied, contact forces between fibres form the dominant contribution to the normal stress differences.

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42

Harlen, O. G., and Donald L. Koch. "Simple shear flow of a suspension of fibres in a dilute polymer solution at high Deborah number." Journal of Fluid Mechanics 252 (July 1993): 187–207. http://dx.doi.org/10.1017/s0022112093003726.

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The behaviour of fibre suspensions in dilute polymer solutions at high Deborah numbers is analysed. In particular, we calculate the change to the extension of the polymers and the orientation of the fibres caused by hydrodynamic interactions between the polymers and the fibres. At a sufficiently high Deborah number the combined effect of the fibre velocity disturbances and the mean shear flow produce a dramatic increase in the extension of the polymers, similar to the coil-stretch transition observed in extensional flow.The non-Newtonian stresses caused by the polymers produce a perturbation to the angular velocity of the fibres, giving rise to a net drift across Jeffery orbits towards the vorticity axis. Unlike the second-order-fluid analysis of Leal (1975), this effect does not depend on the second-normal-stress difference.

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43

Milliken, William J., Moshe Gottlieb, Alan L. Graham, Lisa A. Mondy, and Robert L. Powell. "The viscosity-volume fraction relation for suspensions of rod-like particles by falling-ball rheometry." Journal of Fluid Mechanics 202 (May 1989): 217–32. http://dx.doi.org/10.1017/s0022112089001163.

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The relative viscosities of suspensions of randomly oriented rods in a Newtonian fluid were measured using falling-ball rheometry. The rods were monodisperse and sufficiently large to render colloidal and Brownian forces negligible. Steel and brass ball bearings were dropped along the centreline of cylindrical columns containing the suspensions. The terminal velocities of the falling balls were measured and used to determine the average viscosities of the suspensions. The suspensions behaved as Newtonian fluids in that they were characterized by a constant viscosity. They exhibited a linear relative viscosity-volume fraction relationship for volume fractions less than 0.125, and, for volume fractions between 0.125 and 0.2315, the specific viscosity increased with the cube of the volume fraction. The relative viscosity was found to be independent of falling-ball size for a ratio of falling ball to fibre length greater than 0.3. It was found to be independent of the diameter of the containing cylindrical column for a ratio of column diameter to fibre length greater than 3.2. The value determined for the intrinsic viscosity is in good agreement with theoretical predictions for suspensions of randomly oriented rods.

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44

Gibson, A. G., and S. Toll. "Mechanics of the squeeze flow of planar fibre suspensions." Journal of Non-Newtonian Fluid Mechanics 82, no. 1 (April 1999): 1–24. http://dx.doi.org/10.1016/s0377-0257(98)00127-x.

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45

Djalili-Moghaddam, Mina, and Staffan Toll. "A model for short-range interactions in fibre suspensions." Journal of Non-Newtonian Fluid Mechanics 132, no. 1-3 (December 2005): 73–83. http://dx.doi.org/10.1016/j.jnnfm.2005.08.014.

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46

Aitomäki, Yvonne, and Torbjörn Löfqvist. "Material property estimates from ultrasound attenuation in fibre suspensions." Ultrasonics 49, no. 4-5 (May 2009): 432–37. http://dx.doi.org/10.1016/j.ultras.2008.11.005.

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47

Bhole, M., C. Ford, and C. P. J. Bennington. "Characterization of axial flow impellers in pulp fibre suspensions." Chemical Engineering Research and Design 87, no. 4 (April 2009): 648–53. http://dx.doi.org/10.1016/j.cherd.2008.11.002.

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48

Souloumiac, Bruno, and M. Vincent. "Steady shear viscosity of short fibre suspensions in thermoplastics." Rheologica Acta 37, no. 3 (June 29, 1998): 289–98. http://dx.doi.org/10.1007/s003970050116.

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49

Zhang, Feng, Anders A. Dahlkild, and Fredrik Lundell. "Nonlinear disturbance growth during sedimentation in dilute fibre suspensions." Journal of Fluid Mechanics 719 (February 19, 2013): 268–94. http://dx.doi.org/10.1017/jfm.2013.4.

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AbstractDisturbances in a dilute fibre suspension are studied with an Eulerian approach. Based on a linear stability analysis, it is shown that inertia and hydrodynamic diffusion damp perturbations at long wavelengths and short wavelengths, respectively, leading to a wavenumber selection. For small but finite Reynolds number of the fluid bulk motion, the most unstable wavenumber is a finite value, which increases with Reynolds number. Furthermore, the diffusion narrows the range of unstable wavenumbers. Numerical simulations of the full nonlinear evolution in time of a normal-mode perturbation show that the induced flow may either die out or saturate on a finite amplitude. The character of this long-time behaviour is dictated by the wavenumber and the presence or absence, as well as nature, of the translational and rotational diffusivities.

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50

Baloch, A., and M. F. Webster. "A computer simulation of complex flows of fibre suspensions." Computers & Fluids 24, no. 2 (February 1995): 135–51. http://dx.doi.org/10.1016/0045-7930(94)00023-r.

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