ORCID Profile
0000-0001-5263-2817
Current Organisation
Universidad Nacional de Educación a Distancia
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Publisher: Cambridge University Press (CUP)
Date: 18-10-2019
DOI: 10.1017/JFM.2019.753
Abstract: We study the rheology of a non-colloidal suspension of rigid spherical particles interacting with a viscoelastic matrix. Three-dimensional numerical simulations under shear flow are performed using the smoothed particle hydrodynamics method and compared with experimental data available in the literature using different constant-viscosity elastic Boger fluids. The rheological properties of the Boger matrices are matched in simulation under viscometric flow conditions. Suspension rheology under dilute to semi-concentrated conditions (i.e. up to solid volume fraction $\\unicode[STIX]{x1D719}=0.3$ ) is explored. It is found that at small Deborah numbers $De$ (based on the macroscopic imposed shear rate), relative suspension viscosities $\\unicode[STIX]{x1D702}_{r}$ exhibit a plateau at every concentration investigated. By increasing $De$ , shear thickening is observed, which is related to the extensional thickening of the underlying viscoelastic matrix. Under dilute conditions ( $\\unicode[STIX]{x1D719}=0.05$ ), numerical results for $\\unicode[STIX]{x1D702}_{r}$ agree quantitatively with experimental data in both the $De$ and $\\unicode[STIX]{x1D719}$ dependences. Even under dilute conditions, simulations of full many-particle systems with no a priori specification of their spatial distribution need to be considered to recover precisely experimental values. By increasing the solid volume fraction towards $\\unicode[STIX]{x1D719}=0.3$ , despite the fact that the trend is well captured, the agreement remains qualitative with discrepancies arising in the absolute values of $\\unicode[STIX]{x1D702}_{r}$ obtained from simulations and experiments but also with large deviations existing among different experiments. With regard to the specific mechanism of elastic thickening, the microstructural analysis shows that elastic thickening correlates well with the average viscoelastic dissipation function $\\unicode[STIX]{x1D703}^{elast}$ , requiring a scaling as $\\langle \\unicode[STIX]{x1D703}^{elast}\\rangle \\sim De^{\\unicode[STIX]{x1D6FC}}$ with $\\unicode[STIX]{x1D6FC}\\geqslant 2$ to take place. Locally, despite the fact that regions of large polymer stretching (and viscoelastic dissipation) can occur everywhere in the domain, flow regions uniquely responsible for the elastic thickening are well correlated to areas with significant extensional component.
Publisher: American Physical Society (APS)
Date: 05-03-3013
Publisher: American Physical Society (APS)
Date: 15-12-2120
Publisher: AIP Publishing
Date: 20-01-2018
DOI: 10.1063/1.3050100
Abstract: Dissipative particle dynamics (DPD) as a model of fluid particles suffers from the problem that it has no physical scale associated with the particles. Therefore, a DPD simulation requires an ambiguous fine-tuning of the model parameters with the physical parameters. A corrected version of DPD that does not suffer from this problem is smoothed dissipative particle dynamics (SDPD) [P. Español and M. Revenga, Phys. Rev. E 67, 026705 (2003)]. SDPD is, in fact, a version of the well-known smoothed particle hydrodynamics method, albeit with the proper inclusion of thermal fluctuations. Here, we show that SDPD produces the proper scaling of the fluctuations as the resolution of the simulation is varied. This is investigated in two problems: the Brownian motion of a spherical colloidal particle and a polymer molecule in suspension.
Publisher: Springer Science and Business Media LLC
Date: 06-03-2012
Publisher: American Physical Society (APS)
Date: 23-10-2003
Publisher: Society of Rheology
Date: 21-11-2022
DOI: 10.1122/8.0000527
Abstract: Constitutive models for the dynamics of polymer solutions traditionally rely on closure relations for the extra stress or related microstructural variables (e.g., conformation tensor) linking them to flow history. In this work, we study the eigendynamics of the conformation tensor within the GENERIC framework in mesoscopic computer simulations of polymer solutions to separate the effects of nonaffine motion from other sources of non-Newtonian behavior. We observe that nonaffine motion or slip increases with both the polymer concentration and the polymer chain length. Our analysis allows to uniquely calibrate a mixed derivative of the Gordon–Schowalter type in macroscopic models based on a micro-macromapping of the dynamics of the polymeric system. The presented approach paves the way for better polymer constitutive modeling in multiscale simulations of polymer solutions, where different sources of non-Newtonian behavior are modelled independently.
Publisher: Elsevier BV
Date: 10-2007
Publisher: American Physical Society (APS)
Date: 05-10-2010
Publisher: American Physical Society (APS)
Date: 22-05-2009
Publisher: Springer Science and Business Media LLC
Date: 30-12-2017
Location: No location found
No related grants have been discovered for Pep Español.