Effects due to the solvent density distribution on the dynamics of polymer coils in solution under rheological flow fields
Year: 2026
Type: preprint
Abstract: We study the behaviour of highly resolved polymer chains under rheological flow fields encompassing varying levels of hydrodynamic interactions (HI) using dissipative particle dynamics (DPD) simulations. The chains are discretized to a single Kuhn step, while the spring lengths set the level of HI. While the overall trends agree with Brownian dynamics (BD) simulations of similarly resolved chains, the balance of drag and restoring spring forces is unable to explain the chain stretch obtained for DPD simulations with higher HI (lower spring length) at moderately large flow rates. For compact coils showing high levels of HI in DPD simulations, the solvent density remains low deep inside the coil, which persists to some extent even as the chains stretch at higher flow rates. In contrast, the solvent density remains nearly constant, at the bulk value, across expanded coils with larger spring lengths. We show how this density distribution has implications for the viscosity of the interface between the polymer coil and solvent and provides a correction to the viscosity used in the drag force expression, which explains the chain stretch values observed in simulations. CFD simulations show the decay of the influence of one sphere on another beyond a separation of one diameter and the persistence of the same for a linear array of spheres, which allows the assumption of a thin cylinder for the drag force.
Source: ChemRxiv
Institution: Indian Institute of Technology Kanpur
Language: English
Subfield: Fluid Flow and Transfer Processes
Field: Chemical Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7212039519