On the boundary conditions for dissipative particle dynamics (DPD)

Abstract

Dissipative Particle Dynamics is a mesoscale simulation technique that is widely used in simulation of complex fluids. This method simulates the fluid in the scales between microscopic and macroscopic scales. In this thesis, we aim at developing a new wall model in which there is virtually no density fluctuation near the wall boundary. Two test cases of Couette flow and lid driven cavity have been done to show that DPD can be used successfully to validate the results. In order to simulate flows where periodic boundary condition cannot be applied, a source-sink method is employed in which the particles are injected and removed from the system to induce the flow. It is found that extrapolating velocities at the inlet yields a better velocity profile as that of a developed flow. Localized acceleration of particles has also been applied to reduce the distortions in the velocity at the inlet. Parallel computing is employed and it is shown that the speedup reaches saturation as the number of CPUs increase.