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We investigate flocculation in dilute suspensions of rigid, straight fibers in a decel- erating flow field of a diffuser. We carry out numerical studies using a particle-level simulation technique that takes into account the fiber inertia and the non-creeping fiber–flow interactions. The fluid flow is governed by the Reynolds-averaged Navier– Stokes equations with the standard k-ω eddy-viscosity turbulence model. A one-way coupling between the fibers and the flow is considered with a stochastic model for the fiber dispersion due to turbulence. The fibers interact through short-range attractive forces that cause them to aggregate into flocs when fiber–fiber collisions occur. We show that ballistic deflection of fibers greatly increases the flocculation in the diffuser. The inlet fiber kinematics and the fiber inertia are the main parameters that affect fiber flocculation in the pre-diffuser region.

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ANDRIĆ, Jelena S. et al. PARTICLE-LEVEL SIMULATIONS OF FLOCCULATION IN A FIBER SUSPENSION FLOWING THROUGH A DIFFUSER. Thermal Science, [S.l.], mar. 2017. ISSN 2334-7163. Available at: <>. Date accessed: 24 feb. 2018. doi:
Received 2017-03-10
Accepted 2017-03-14
Published 2017-03-14


[1] Andric´, J., Numerical modeling of air–fiber flows, PhD thesis, Chalmers University of Technology, Go¨teborg, Sweden, ISBN 978-91-7597-010-3, May 2014.
[2] Adin A., Asano T., The role of physical-chemical treatment in wastewater reclamation and reuse, Water Science and Technology 37 (1998), pp. 79-90.
[3] Guibai L., Gregory J., Flocculation and sedimentation of high-turbidity waters, Wat. Res. 25 (1991), pp. 1137-1143.
[4] Schmid C. F., et al., Simulation of fiber flocculation: Effects of fiber properties and interfiber friction, J. Rheol. 44 (2000), pp. 781-809.
[5] Switzer L.H., et al., Handsheet formation and mechanical testing via fiber-level simulations, Nord. Pulp Pap. Res. J. 19 (2004), pp. 434-439.
[6] Do-Quang M, et al., Simulation of finite-size fibers in turbulent channel flows, Phys. Rev. E 89 (2014), p. 013006.
[7] Jafari A., et al., Multiscale modeling of fluid turbulence and flocculation in fiber suspensions, J. Appl. Phys. 100, (2006), p. 034901.
[8] Ha¨ma¨la¨inen J., et al., Papermaking fiber suspension flow simulations at multiple scales, J. Eng. Math. 71 (2011) 1, pp. 55-79.
[9] Ramkrishna D., Population balances–theory and applications to particulate systems in engineering, Academic Press, San Diego, 2000.
[10] Andric´ J., et al., Ballistic deflection of fibres in decelerating flow, Int. J. Multiphas. Flow 85 (2016), pp. 57-66.
[11] Wilcox D. C., Turbulence modeling for CFD, DCW Industries, Inc., California, 1993.
[12] Lindstro¨m S.B., Ueasaka T., Simulation of the motion of flexible fibers in viscous fluid flow, Phys. Fluids 19 (2007), p. 113307.
[13] Andric´ J., et al., A study of a flexible fiber model and its behavior in DNS of turbulent channel flow, Acta Mech. 224 (2013), pp. 2359-2374.
[14] Gosman A. D., Ioannides E., Aspects of computer simulations of liquid-fueled combustors, J. Energy 7 (1983), pp. 482-490.
[15] Kim S., Karilla S.J., Microhydrodynamics: Principles and Selected Applications, Butterworth– Heinemann, Stoneham, 1991.
[16] Tritton D.J., Physical fluid dynamics, Clarendon, Oxford, 1988.
[17] Vega C., Lago S., A fast algorithm to evaluate the shortest distance between rods, Computers Chem. 18 (1994), pp. 67-87.
[18] Buice C.U., Eaton J.K., Experimental investigation of flow through an asymmetric plane diffuser, J. Fluids Eng. 123 (2001), pp. 819-828.
[19] Versteeg H.K., Malalasekera W., An introduction to computational fluid dynamics, Pearson Education Limited, 1995.
[20] Jasak H., Error analysis and estimation for the Finite Volume method with application to fluid flows, PhD thesis, Imperial College, University of London, 1996.
[21] Obi S., et al., Experimental and computational study of turbulent separating flow in an asymmetric plane diffuser, in 9th Symposium on Turbulent Shear Flows, Kyoto, Japan 16-19 August, 1993.
[22] El-Behery S.M., Hamed M.H., A comparative study of turbulence models performance for separating flow in a planar asymmetric diffuser, Comput. Fluids 44 (2011), pp. 248-257.