CUED Publications database

Slip flow and heat transfer in microbearings with fractal surface topographies

Zhang, W-M and Meng, G and Wei, X-Y and Peng, Z-K (2012) Slip flow and heat transfer in microbearings with fractal surface topographies. International Journal of Heat and Mass Transfer, 55. pp. 7223-7233. ISSN 0017-9310

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Abstract

The effects of random surface roughness on slip flow and heat transfer in microbearings are investigated. A three-dimensional random surface roughness model characterized by fractal geometry is used to describe the multiscale self-affine roughness, which is represented by the modified two-variable Weierstrass- Mandelbrot (W-M) functions, at micro-scale. Based on this fractal characterization, the roles of rarefaction and roughness on the thermal and flow properties in microbearings are predicted and evaluated using numerical analyses and simulations. The results show that the boundary conditions of velocity slip and temperature jump depend not only on the Knudsen number but also on the surface roughness. It is found that the effects of the gas rarefaction and surface roughness on flow behavior and heat transfer in the microbearing are strongly coupled. The negative influence of roughness on heat transfer found to be the Nusselt number reduction. In addition, the effects of temperature difference and relative roughness on the heat transfer in the bearing are also analyzed and discussed. © 2012 Elsevier Ltd. All rights reserved.

Item Type: Article
Uncontrolled Keywords: Fractal geometry Heat transfer Microbearing Random roughness Rarefaction Slip flow
Subjects: UNSPECIFIED
Divisions: Div C > Applied Mechanics
Depositing User: Cron Job
Date Deposited: 07 Mar 2014 11:29
Last Modified: 08 Dec 2014 02:38
DOI: 10.1016/j.ijheatmasstransfer.2012.07.045