Modeling aspects of excluded volume and hydrodynamic interactions in dissipative particle dynamics simulations of highly resolved polymer chains in flow fields

Even though the Dissipative Particle Dynamics (DPD) technique has shown its worth in a variety of research areas, it has been rarely used for polymer dynamics, particularly in dilute and semi-dilute conditions and under imposed flow fields. For such applications, the most popular technique has been Brownian dynamics (BD), even though the formulation of the same may be complicated for flow in complex geometries, which is straightforward for DPD. This is partly due to the flexibility of BD simulations to mimic any dynamic regime for polymer solutions by independently tuning hydrodynamic interactions (HI) and excluded volume (EV). In this study with highly resolved polymer chains, we reveal that DPD also offers a similar flexibility and the regimes with respect to dominant EV and HI can be selected as conveniently as BD. This flexibility is achieved by tuning the repulsive interaction parameter of polymer beads and the spring length. Any rheological regime of certain level of EV and HI can be attained by appropriately tuning only these two parameters, providing a flexibility of similar levels as BD simulations. We further highlight the suitability of DPD by comparing predictions with equivalent models in BD, for highly resolved chains in flow fields. For this, we imposed startup uniaxial extensional flows and steady shear flows on the system. Our results indicate the consistency of DPD with BD simulations, which is known to agree well with experiments. Finally, we provide a simple analytical estimate of the level of HI in any DPD simulation, as a function of relevant DPD parameters.