title: Steady shear rheometry of dissipative particle dynamics models of polymer fluids in reverse Poiseuille flow.
abstract: Polymer fluids are modeled with dissipative particle dynamics (DPD) as undiluted bead-spring chains and their solutions. The models are assessed by investigating their steady shear-rate properties. Non-Newtonian viscosity and normal stress coefficients, for shear rates from the lower to the upper Newtonian regimes, are calculated from both plane Couette and plane Poiseuille flows. The latter is realized as reverse Poiseuille flow (RPF) generated from two Poiseuille flows driven by uniform body forces in opposite directions along two-halves of a computational domain. Periodic boundary conditions ensure the RPF wall velocity to be zero without density fluctuations. In overlapping shear-rate regimes the RPF properties are confirmed to be in good agreement with those calculated from plane Couette flow with Lees-Edwards periodic boundary conditions (LECs), the standard virtual rheometer for steady shear-rate properties. The concentration and the temperature dependence of the properties of the model fluids are shown to satisfy the principles of concentration and temperature superposition commonly employed in the empirical correlation of real polymer-fluid properties. The thermodynamic validity of the equation of state is found to be a crucial factor for the achievement of time-temperature superposition. With these models, RPF is demonstrated to be an accurate and convenient virtual rheometer for the acquisition of steady shear-rate rheological properties. It complements, confirms, and extends the results obtained with the standard LEC configuration, and it can be used with the output from other particle-based methods, including molecular dynamics, Brownian dynamics, smooth particle hydrodynamics, and the lattice Boltzmann method.
authors.affiliation: Division of Applied Mathematics, Brown University, Providence, Rhode Island 02912, USA.
authors.forename: Dmitry A
authors.initials: DA
authors.lastname: Fedosov
authors.forename: George Em
authors.initials: GE
authors.lastname: Karniadakis
authors.forename: Bruce
authors.initials: B
authors.lastname: Caswell
mesh_terms: D056004:Molecular Dynamics Simulation; D011108:Polymers / Q000737:chemistry*; D012212:Rheology; D012996:Solutions; D013696:Temperature; D013816:Thermodynamics; D014783:Viscosity
chemical_list: D011108:Polymers; D012996:Solutions
references.citation: J Chem Phys. 2005 Apr 15;122(15):154503
references.pmid: 15945641
references.citation: Phys Rev Lett. 2006 Jun 9;96(22):224505
references.pmid: 16803314
references.citation: J Chem Phys. 2006 Nov 14;125(18):184902
references.pmid: 17115790
references.citation: J Chem Phys. 2008 Apr 14;128(14):144903
references.pmid: 18412478