Most of Alan Vardy’s academic research has been undertaken in active collaboration with colleagues in Scotland and in countries as far away as Japan, the USA and Australia. Special mention must be made of Dr Jim Brown, who has played a pivotal role in Dundee. Without his skills and dedication, much of Vardy’s academic research would not have been possible.
Topics that have given special satisfaction include:
• wave propagation in pipes and pipe networks
• fluid-structure interaction in suspended pipe systems
• unsteady friction in pipes and ducts
• numerical methods for unsteady flow analysis
Studies of wave propagation in pipes and pipe networks have been motivated primarily by applications related to water supply, hydro-electric power and railway tunnels. In each case, sudden events can cause strongly unsteady flows characterised by pressure waves propagating through the system and reflecting at internal and external boundaries.
In many pipe/duct systems, wave propagation has little influence on the containing conduit other than, perhaps, stressing of the pipe wall in response to internal pressure changes. In the particular case of suspended pipe systems, however, dynamic Fluid-Structure Interaction can be induced, potentially leading to vibration and fatigue. Some very serious incidents have resulted from this behaviour in major installations including power stations and overground oil supply lines.
In the absence of friction between fluids and the internal surfaces of pipes, etc, the analysis of wave propagation would be relatively straightforward. In fact, it is usually not too demanding even in the presence of friction. A major exception to this rule arises, however, in regions of strongly unsteady flow close to the most rapidly changing parts of waves. In such regions, allowance must be made for unsteady friction that depends upon rates of acceleration as well as upon the velocity of flow. Vardy and Brown can claim a degree of world leadership on this research topic for over two decades.
In addition to the need to develop realistic analytical models of physical phenomena associated with wave propagation, it is vitally important to have numerical methods suitable for solving the resulting equations. Vardy has several decades experience in the development of robust and accurate numerical methods. In recent years, work with Professor Masashi Shimada, initially at the University of Tokyo and now at Tsukuba University, has had the higher level aim of minimising the need for software users to familiarise themselves with numerical matters.
