We use dynamical systems theory to construct the normal form of the Navier–Stokes equations for the flow of a thin layer of fluid upon a solid substrate. The normal form equations illuminate the fluid dynamics by decoupling the long-term flow of interest from the rapid viscous decay of the transient shear modes. The normal form clearly shows the centre manifold of the lubrication model and show...

Micro lubrication or also known as minimum quantity lubrication (MQL) serves as an alternative to flood cooling by reducing the volume of cutting fluid used in the machining process; but not without significant health concerns. Flood cooling is primarily used to cool and lubricate the cutting tool and work piece interface during machining process. The adverse health effects caused by the use of...

We consider constant volume thin film slurries on an incline. Clear fluids in this geometry are known to have a front position that moves according to a t scaling law, based on similarity solution analysis [Huppert, Nature, 1982]. We investigate the same dynamics for particle laden flow using a recently proposed lubrication model for the slurry and physical experiments. Our analysis includes th...

In the context of glass fiber manufacture, the onset of lubrication by a C(18) double-chained cationic surfactant has been investigated at high normal contact pressures. Comparison with adsorption kinetics demonstrates that lubrication is not directly connected to the surfactant surface excess but originates from the transition to a defect-free bilayer that generates limited dissipation. The im...

In this paper the drag-out problem for shear-thinning liquids at variable inclination angles is considered. For this free boundary problem dimension-reduced lubrication equations are derived for the most commonly used viscosity models, namely, the power-law, Ellis, and Carreau model. For the resulting lubrication models a system of ordinary differential equations governing the steady state solu...

This paper presents experimental measurements of the approach and rebound of a particle colliding obliquely with a wall in a viscous fluid. Steel and glass particles 12.7mm in diameter were used. The experiments were performed using a thick Zerodur wall (a glass-like material) with various mixtures of glycerol and water. Normal and tangential coefficients of restitution were defined from the ra...

The lubrication regime in which artificial hip joints operate adds complexity to the prediction of wear, as the joint operates in both the full fluid film regime-specifically the elastohydrodynamic lubrication (EHL) regime-and the mixed or boundary lubrication regimes, where contact between the bearing surfaces results in wear. In this work, a wear model is developed which considers lubrication...

A recent study in South Africa has confirmed, for the first time, that a vaginal gel formulation of the antiretroviral drug Tenofovir, when applied topically, significantly inhibits sexual HIV transmission to women [10]. However the gel for this drug, and anti-HIV microbicide gels in general, have not been designed using full understanding of how gel spreading and retention in the vagina govern...

Artificial total hip arthroplasty (THA) is one of the most effective orthopaedic surgeries that has been used for decades. However, wear of the articulating surfaces is one of the key failure causes limiting the lifetime of total hip implant. In this paper, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were employed to e...

This thesis focuses on reliability when testing gear efficiency and on how gear mesh efficiency can be increased without detrimental effects on the gears. Test equipment commonly used in gear research was analysed to identify important parameters for gear efficiency testing. The effect of the bearing model’s load-dependent losses on gear mesh efficiency was also investigated. Two different surf...