Effect of viscoelasticity on the rotation of a sphere in shear flow |
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| Authors: | F Snijkers G D’Avino PL Maffettone F Greco MA Hulsen J Vermant |
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| Institution: | 1. Department of Chemical Engineering, K.U. Leuven, W. de Croylaan 46, B-3001 Leuven, Belgium;2. Dipartimento di Ingegneria Chimica, Università di Napoli Federico II, Piazzale Tecchio 80, 80125 Naples, Italy;3. Istituto di Ricerche sulla Combustione, IRC-CNR, Piazzale Tecchio 80, 80125 Naples, Italy;4. Department of Mechanical Engineering, Eindhoven University of Technology, Eindhoven 5600 MB, The Netherlands;1. IOM Ricerca s.r.l., Via Penninazzo 11, 95029 Viagrande, Italy;2. Department of Biomedical and Biotechnological Sciences, University of Catania, Via Santa Sofia 64, 95127 Catania, Italy;1. Department of Mechanical Engineering, Federal University of Rio Grande do Sul, Rua Sarmento Leite 425, Porto Alegre, RS 90050-170, Brazil;2. Department of Mechanical Engineering, Pontifícia Universidade Católica-RJ, Rua Marquês de São Vicente 225, Rio de Janeiro, RJ 22453-900, Brazil;1. Mechanical and Aerospace Engineering Department, Polymer Research Center, King Mongkut’s University of Technology North Bangkok, Bangkok 10800, Thailand;2. Chemical Engineering Department, Queen’s University, Kingston, Ontario K7L 3N6, Canada;3. Polymers Research Group, Queen’s University, Kingston, Ontario K7L 3N6, Canada;1. Departamento de Matemática e Computação, Faculdade de Ciências e Tecnologia, Universidade Estadual Paulista “Júlio de Mesquita Filho”, 19060-900 Presidente Prudente, SP, Brazil;2. Departamento de Engenharia Química, CEFT, Faculdade de Engenharia da Universidade do Porto, Porto, Portugal |
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| Abstract: | When particles are dispersed in viscoelastic rather than Newtonian media, the hydrodynamics will be changed entailing differences in suspension rheology. The disturbance velocity profiles and stress distributions around the particle will depend on the viscoelastic material functions. Even in inertialess flows, changes in particle rotation and migration will occur. The problem of the rotation of a single spherical particle in simple shear flow in viscoelastic fluids was recently studied to understand the effects of changes in the rheological properties with both numerical simulations D’Avino et al., J. Rheol. 52 (2008) 1331–1346] and experiments Snijkers et al., J. Rheol. 53 (2009) 459–480]. In the simulations, different constitutive models were used to demonstrate the effects of different rheological behavior. In the experiments, fluids with different constitutive properties were chosen. In both studies a slowing down of the rotation speed of the particles was found, when compared to the Newtonian case, as elasticity increases. Surprisingly, the extent of the slowing down of the rotation rate did not depend strongly on the details of the fluid rheology, but primarily on the Weissenberg number defined as the ratio between the first normal stress difference and the shear stress.In the present work, a quantitative comparison between the experimental measurements and novel simulation results is made by considering more realistic constitutive equations as compared to the model fluids used in previous numerical simulations D’Avino et al., J. Rheol. 52 (2008) 1331–1346]. A multimode Giesekus model with Newtonian solvent as constitutive equation is fitted to the experimentally obtained linear and nonlinear fluid properties and used to simulate the rotation of a torque-free sphere in a range of Weissenberg numbers similar to those in the experiments. A good agreement between the experimental and numerical results is obtained. The local torque and pressure distributions on the particle surface calculated by simulations are shown. |
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