A comparison of homogenization and averaging techniques for the treatment of roughness in slip-flow-modified Reynolds equation

This article is concerned with the simulation of a magnetic storage device consisting of a flying head above a rigid rotating disk. The need to improve the transfer rate has led, at present, to very small surface-to-surface distances (air gaps). In this situation it is compulsory, to take into account roughness effects. A popular method consists in averaging film-thickness from Mitsuya et al. (1989), with good reported results compared with experimental data. To overcome some limitations that become apparent at very small air gaps, notably when the roughness is two-dimensional, Jai ill 1995 introduced a new technique based oil a rigorous homogenization theory. Recent developments from Buscaglia and Jai (2000) have greatly reduced the computational complexity of the homogenization-based method, rendering it suitable for practical applications. Me propose ill this paper an original approach based oil strength and rigorous mathematical model to avoid numerical problems which are usually encountered ill classical approaches. The validation of the homogenization-based method is ill some sense, a generalization of the film-averaging technique suitable for configurations ill which some parameters of the latter (such as the Boltzmann correction factor) are not unambiguously defined.