Dissipative particle dynamics with predetermined input parameters for particulate suspensions

This PhD project reports a new Dissipative Particle Dynamics (DPD) scheme for numerically investigating the behaviour of complex fluids at the mesoscale. Its attractive features include (i) the input parameters are directly determined from the physical fluid properties: the mass density, water compressibility, time-scale ratio, viscosity and dynamic response; and (ii) the transport coefficients are also considered as functions of the wavelengths and frequencies of thermal fluctuations (i.e. generalised hydrodynamics). With its pre-determined input parameters, the proposed DPD is shown to possess a consistent scaling of thermal fluctuations and produce similar behaviours of the flow at different levels of coarse-graining. With its generalised hydrodynamic regime employed, the proposed DPD method is shown to have the ability to model a viscoelastic fluid using a single set of particles, and the ability to take into account size effects caused by suspended objects. Compressibility is also studied, and a simple approach based on the time-scale ratio is proposed and shown to be effective. Improved results have been achieved in the simulation of viscometric and non-viscometric flows of simple (single phase) and complex (multiphase) fluids