![Sample our Physical Sciences journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/110819/TOC-Subject-Sample-2021-Physical-Sciences.jpg"})
Abstract
The expansion of argon jets from cylindrical microtubes is investigated using a three-dimensional unstructured direct simulation Monte Carlo (DSMC) method. The simulation results for a microtube with an aspect ratio (tube length to diameter) of 1.5 are shown to compare well with theoretical formulations of free-jet expansion. The DSMC simulations are performed in computational domains that feature both an internal microtube region and external jet expansion region. Microtubes with orifice diameters ranging between 100 μm and 100 nm are used in the simulations in order to investigate the effects of Knudsen number, aspect ratio, Reynolds number, and microtube scale on jet structure. The jet shape is shown to narrow with increasing Knudsen number, increasing aspect ratio and decreasing Reynolds number. The reduction in relative number density along the flow axis is shown to decrease with increasing Knudsen number and Reynolds number.
This work was partially supported by NSF's NIRT Program through Grant DMI-0210258 and AFOSR's Computational Mathematics Program through Grant F49620-03-1-0219 and Grant FA9550-06-1-0236.