Modeling of microscale gas flows in transition regime Part I: Flow over backward facing steps

Abstract

Design of thermal management solutions for future nanoscale electronics or photonics devices will require knowledge of flow and transport through micron-scale ducts. This article concentrates on a typical flow process, namely flow over a backward-facing step with pressure boundary conditions at inlet and exit. Discrete simulation Monte Carlo (DSMC) is used as the simulation tool. An IP method is used to separate the macroscopic velocity from the molecular velocity, thus reducing statistical noise as typical in DSMC calculation of lowspeed flows. Simulation is conducted for Re of 0.03 to 0.64, Ma of 0.013 to 0.083, and Kn of 0.24 to 4.81. For these parameter values no recirculating region is observed, and the high heat flux associated with reattachment is also absent.