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Numerical predictions of the order two Batchelor’s coefficient for the dynamic and complex viscosity of a non Brownian suspension
No full textViscosity of semidilute suspensions of rigid spheres in a newtonian fluid: numerical predictions of the order two expansion in the sphere concentration
No full textNumerical predictions of the viscosity of non Brownian suspensions in the semidilute regime
No full textThe viscosity of a non-Brownian suspension in simple shear cannot be theoretically predicted in the limit of the semidilute approximation, since it depends on the initial configuration. Batchelor and Green [J. Fluid Mech. 56, 401-427 (1972)] proved that the suspension viscosity can be expressed in power series of the solid volume fraction and the second order coefficient, b, resulted undetermined. On the contrary, experimentally Pasquino [J. Rheol. 52, 1369-1384 (2008)] obtained a single steady state and estimated the value of b. We here numerically show that laminar mixing is able to induce a unique steady state also in the semidilute regime, since it is effective to break the closed orbits that may occur in these suspensions. To this end, we investigated the effect of the initial conditions on the steady state starting from seven different configurations ranging from the fully uniform and ordered one to the agglomerated one, passing through different random distributions. We, finally, numerically predict, via Stokesian dynamics, the coefficient b for the viscosity of a monolayer of rigid spherical particles suspended in a Newtonian fluid, undergoing simple shear flow obtaining b = 6.5 in a good agreement with both the data of Pasquino and the theoretical predictions obtained under the hypothesis of absence of closed orbits [Wilson and Davis J. Fluid. Mech. 421, 339-367 (2000)]. It is also shown that the Cox-Merz rule is fulfilled by the suspensions that we have numerically studied, i.e., up to a volume fraction of about 0.17. (C) 2011 The Society of Rheology. [DOI: 10.1122/1.3630943
Very early stage of the structure reorganisation of Newtonian suspensions under oscillatory shear
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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