%0 Journal Article
%T Inertia Effects in the Flow of a Herschel-Bulkley ERF between Fixed Surfaces of Revolution
%A A. Walicka
%A J. Falicki
%J Smart Materials Research
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/171456
%X Many electrorheological fluids (ERFs) as fluids with microstructure demonstrate viscoplastic behaviours. Rheometric measurements indicate that some flows of these fluids may be modelled as the flows of a Herschel-Bulkley fluid. In this paper, the flow of a Herschel-Bulkley ER fluid¡ªwith a fractional power-law exponent¡ªin a narrow clearance between two fixed surfaces of revolution with common axis of symmetry is considered. The flow is externally pressurized, and it is considered with inertia effect. In order to solve this problem, the boundary layer equations are used. The influence of inertia forces on the pressure distribution is examined by using the method of averaged inertia terms of the momentum equation. Numerical examples of externally pressurized ERFs flows in the clearance between parallel disks and concentric spherical surfaces are presented. 1. Introduction In recent years, the study of fluids with microstructures has gained much importance because of its numerous applications in various engineering disciplines such as chemical engineering, polymer processing, plastic forming foundry engineering, and engineering of lubrication [1¨C14]. In machines and mechanisms systems of many industrial processes, the phenomena of a flow of viscoplastic fluids are used. One of these phenomena is a slide bearing lubrication [9, 10, 13]. Advances in technology and severe operational requirements of machines necessitated the development of improved lubricants to ensure a smooth and safe operation. Generally, viscosity of lubricants decreases with temperature. For operations under high speeds and heavy loads, oils containing high molecular weight polymers as viscosity index improvers are used to increase a load carrying capacity of the modified lubricants [9, 13]. Most substances used in the lubrication technology are polymer solutions, thus, the characteristics of the bearings change when such rheological substances, known as non-Newtonian fluids, are used as lubricants. Several constitutive relations applied were used to model the non-Newtonian characteristics exhibited by some lubricants [7, 11, 13, 15, 16]. Another ones of these phenomena are processes of vibration control and torque transmission. In the last years, the electrorheological fluids (abbreviated to ERFs) have acquired a great relevance for supporting vibration control and torque transmission devices, based on the characteristic dependence of their viscosity on applied electric field strength. Since their initial discovery by Winslow [17], many particle-dispersion electrorheological fluids,
%U http://www.hindawi.com/journals/smr/2013/171456/