This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.In this paper, a lattice Boltzmann method used in the simulation of the fluid flow in micro/nano scale is introduced and studied.
The method can be employed instead of NS equations in cases where the continuum assumption is no longer valid. In the present
study the aim is to investigate the effects of surface roughness on flow characteristics of micro/nano gas flows. In order to compare the final results, two flow geometries were chosen for which the numerical and experimental results were available. Surface roughness was increased in each stage (from completely smooth to 12% roughness) and its influences on the flow regime, pressure and velocity distribution, slip velocity and mass flow rate were studied. It is shown that surface roughness results in a decrease in the mass flow rate as well as slip velocity. Increasing the amount of roughness causes the mass flow rate to continually decrease, however this trend is inverted for the slip velocity
