Mesoscopic simulation of fluid flow in periodically grooved microchannels

Abstract

In the present work we investigate the effect of wall protrusions on flows in microchannels using Dissipative Particle Dynamics (DPD). Protrusions are introduced by periodically placing rectangular protruding elements on the upper channel wall. The protrusion length and height are varied and their effect on the flow is examined. Periodic boundary conditions are imposed in the streamwise and spanwise directions. Bounce-back reflecting boundary conditions are enforced at the fluid-solid wall interface. Simulations are performed for a range of values of the external driving force. Analysis of fluid particle trajectories and average residence time reveals temporary trapping of fluid inside the upper wall cavities for a considerable amount of time. This trapping affects macroscopic quantities such as density, velocity, pressure and temperature distribution inside and close to the cavities as well as the functional relations between the flow friction factor and the flow Reynolds number. When compared to the channel with flat walls, lower flow velocities are observed in the core region of the channel. The reduction of velocities as the protrusion size varies is quantified. Density, pressure and temperature remain almost constant in the core of the channel and their distribution near and inside the cavities depend on the protrusion size. For all channel cases, the friction factor/Reynolds number relationship, follows a power law relation of the form, f Re = A = const, i.e. the Poiseuille number of the flow is constant. The value of constant A increases as the protrusion length decreases and the protrusion height increases, and represents the dependence of the flow resistance on the protrusion size. (C) 2013 Elsevier Ltd. All rights reserved.