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Particle movements during the coating process Martti Toivakka and Dan Eklund, Department of Paper Chemistry, ~ b o Akademi University, Finland Keywords: Coating, Hydrodynamics, Shear stress, Rheo- logy, Dilatancy, Viscosity, Stokesian dynamics. SUMMARY:The motion of spherical particles during the coating process is modeled using a modified Stokesian Dyna- mics technique. Particle-particle and particle-boundary hyd- rodynamic interactions, as well as electrostatic and Brownian forces, are included in the model. The simulations yield new information about

Particle motion during shear The influence of particle shape and roughness on rheology Douglas W. Bousfield. Department of Chemical Engineering, University of Maine, Orono, USA Keywords: Rheology, Coatings, Stokesian dynamics, Thixotro- py, Shear flow, Dilatancy. SUMMARY: The influence of a particle's roughness and shape on suspensions rheology is studied with a modified Stokesian dynamics calculation. Particle-particle contact or electrostatic interactions order the particles in shear layers to give shear thinning andlor thixotropic rheology. Large

376 Nordic Pulp and Paper Research Journal Vol 15 no. 5/2000 Keywords: Particle motion modeling, Stokesian dynamics, Blade coating, Blade deposits, Blade wear SUMMARY: Modeling the blade coating process is important because of the high speeds, narrow gaps, and opaque nature of the process. The influence of colloidal forces on the motion of particles is reported using a Stokesian dynamics method. Strong long-range repulsive forces between particles lead to layers of particles and ordered motion of the particles under the blade. When this repulsive force is short

(2010) 125012 (6pp). [9] Hoffman RLJ: Discontinuous and dilatant viscosity behavior in concentrated suspensions. II. Theory and experimental tests, J. Colloid. Interface. Sci. 46 (1974) 491 - 506. [10] Fischer C, Braun SA, Bourban P-E, Michaud V, Plummer CJG, Månson JE: Dynamic properties of sandwich structures with integrated shear-thickening fluids, Smart. Mater. Struct. 15 (2006) 1467 - 1475. [11] Foss DR, Brady JF: Structure, diffusion and rheology of Brownian suspensions by Stokesian dynamics Simulation, J. Fluid. Mech. 407 (2000) 167 - 200. [12] D’Haene PD

(2013) 45397. [5] Hoffman RLJ: Discontinuous and dilatant viscosity be - havior in concentrated suspensions. II. Theory and experimental tests, J. Colloid. Interface Sci. 46 (1974) 491 - 506. [6] Fischer C, Braun SA, Bourban P-E, Michaud V, Plummer CJG,Månson JE: Dynamic properties of sandwich structures with integrated shear-thickening fluids, Smart Mater. Struct. 15 (2006) 1467 - 1475. [7] Foss DR, Brady JF: Structure, diffusion and rheology of Brownian suspensions by Stokesian dynamics Simulation, J. Fluid Mech. 407 (2000) 167 - 200 [8] D’Haene PD, Mewis J, Fuller

References [1] Pal R: Non-idealities in the rheological behavior of suspoemulsions, Chem. Eng. Comm. 121 (1993) 81 - 97. [2] Faers MA, Pontzen R: Factors influencing the association between active ingredient and adjuvant in the leaf de - posit of adjuvant-containing suspoemulsion formulations, Pest Manage. Sci. 64 (2008) 820- 833. [3] Bossis G, Brady JF, Mathis C: Shear-induced structure in colloidal suspensions 1. Numerical-simulation, J. Colloid Interface Sci. 126 (1988) 1 - 15. [4] Banchio AJ, Brady JF: Accelerated stokesian dynamics: Brownian motion, J. Chem

rate. Dynamical models describing the movement of parti- cles subjected to hydrodynamic and colloidal forces are reaching ever higher sophistication. The concept of Stokesian Dynamics (Brady, Bossis 1988) has, with dif- ferent types of modifications (eg. Bousfield 1990; Toivakka 1997; Sierou, Brady 2001), become one of the dominant methods in the simulation of particle motion dynamics in concentrated colloidal suspensions. The main constraint of Stokesian dynamics is the limi- tation on the number of particles to a few 100. However, due to improvements such as the

simple shear flow by numerical simulation, J. Fluid Mech. 155 (1985) 105-129. [14] Brady, J.F. and G. Bossis: Stokesian dynamics, Annu.Rev.Fluid Mech. 20 (1988) 11-157. [15] Kruyt, H.R.: Colloid Science (Elsevier, New York, 1952). [16] Bossis, G. and J.F. Brady: The rheology of Brownian suspensions, J. Chem. Phys. 91 (1989) 1866-1974. [17] Phung, T. and J.F. Brady: Microstructured fluids: Structure, diffusion and rheology of colloidal dispersions, in Slow Dynamics in Condensed Matter, edited by K. Kawasaki et al. (AIP, Woodbury, 1992). [18] Bender, J.W. and N. J

, Demirel AL, Cai LL, Peanasky J: Soft Matter in a Tight Spot: Nanorheology of Confined Liquids and Block Copolymers, Israel J. Chem. 35 (1995) 75-84 [24] Öttinger HC: Stochastic Processes in Polymeric Liquids, Springer-Verlag, Berlin (1996) [25] Doyle P, Shaqfeh E, Gast A: Rheology of polymer brushes: A Brownian dynamics study, Macromolecules 31 (1998) 5474-5486 [26] Brady J, Bossis G: Stokesian Dynamics, Ann. Rev. Fluid Mech. 20 (1988) 111-157 [27] Soga I, Dhinojwala A, Granick S: Optorheological Studies of Sheared confined Fluids with Mesoscopic Thickness, Langmuir 14

reviewed by Vidal, Bertrand (2006). Common numerical methods have included Monte Carlo-based deposition methods (Vidal 2003a,b), or mechanical packing (e.g. Eksi, Bousfield 1997; Hiorns, Nesbitt 2003). The simulation approach utilised in this work is based on Stokesian dynamics (Brady, Bossis 1988), which is a general method used in simulating the motion of colloidal-sized interacting particles in arbitrary flow Influence of drying strategy on coating layer structure formation Anders Sand and Martti Toivakka, Åbo Akademi University, Turku/Åbo, Finland, Tuomo Hjelt, KCL