Simulation of Low Speed Gas Flow Over Backward Facing Step in Microchannels Available to Purchase

Proper design of thermal management solutions for future nano-scale electronics or photonics will require knowledge of flow and transport through micron-scale ducts. As in the macro-scale conventional counterparts, such micron-scale flow systems would require robust simulation tools for early-stage design iterations. This paper concentrates on such a flow process, namely pressure-driven gas flow over a backward facing step in a microchannel. A well-known particle-based method, Direct Simulation Monte Carlo (DSMC) is used as the simulation tool. Separating the macroscopic velocity from the molecular velocity through the use of the Information Preservation (IP) method eliminates the high-level of statistical noise as typical in DSMC calculations of low-speed flows. The non-isothermal IP method is further modified to incorporate the pressure boundary conditions, which are expected to be more prevalent in design of thermal management systems. The applicability of the method in solving a real flow situation is verified using the backward facing step flow in a micro geometry. The flow and heat transfer mechanisms at different pressures in Knudsen transient regime are investigated. The range of parameters for this investigation are: Re from 0.03 to 0.64, Ma from 0.013 to 0.083, and Kn from 0.24 to 4.81, all based on maximum values.