SPH based study of confined microflows characterized by abrupt changes in cross-sectional area

Abstract

In this paper, we investigate the application of Smoothed Particle Hydrodynamics (SPH) method to the computation of flows in microchannels with sudden expansion. Numerical modeling with SPH involves the treatment of flowing matter as distinct mass points, leading to discretization of the Navier-Stokes equations (or other appropriate PDEs) and providing great flexibility to handle large deformations. The computational methodology exhibits similarities with other particle methods, such as Molecular Dynamics (MD), Dissipative Particle Dynamics (DPD), and Smooth Dissipative Particle Dynamics (SDPD). These similarities lead relatively easily to the development of a weakly compressible SPH within the framework of Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS). The LAMMPS environment, albeit mostly intended to MD simulations near the atomic scale, provides a fully parallelized framework for particle simulations, such as SPH. In this work we studied microchannel flows of variable cross section. Sudden expansions generate strong discontinuities in the flow field. Flow models based on various inlet/outlet boundary conditions for example, Periodic/Fixed BCs, and their implementations are presented in the context of 3-D simulations. Minor artifacts may be observed near the wall corner discontinuities, but, overall, the SPH captures the main flow characteristics and achieves very good accuracy