Modified Lees–Edwards boundary condition for dissipative particle dynamics: hydrodynamics and temperature at high shear rates

Abstract

In simulations of Couette shear flow by dissipative particle dynamics (DPD) method, applying traditional Lees–Edwards boundary condition (LEC) in conjunction with velocity-dependent thermostats may result in artefacts in the form of velocity jumps. This artefact was observed at extreme dissipation rates (), and a modified LEC (M-LEC) was introduced to correct that unconditionally (A. Chatterjee, Modification to Lees–Edwards periodic boundary condition for dissipative particle dynamics simulation with high dissipation rates, Mol Simul, 33:1233–1236, 2007). Here we have studied some unexplored effects of using LEC under high shear rate regimes, not only on velocity profiles but also on temperature control. Given a correct temperature () control, the maximum applicable and effective shear velocity, shear rate, dynamic viscosity and Péclet number achievable under both LEC and M-LEC methods are extracted and discussed rigorously. We also show that despite partial success of M-LEC to impose the intended shear rate to the system, it still has some limitations in certain conditions. Here we have explored the advantages and shortcomings of M-LEC on the functionality of DPD thermostat and the calculated rheological properties in moderate to high shear rates and for various weight function exponents.