Department of Mechanical Engineering


Contact details

Room: 4E 2.48

Tel: +44 (0) 1225 383026


PhD supervision

Interested in supervising students studying;

  • Efficient fluid power systems, including digital switching valves
  • Aircraft and automotive hydraulic systems
  • Fluid-borne noise in hydraulic systems: measurement, analysis, active control
  • Hydraulic component and system dynamic modelling
  • Unsteady laminar and turbulent flow in pipes and hoses

Dr Nigel Johnston



Nigel Johnston is a Reader in Mechanical Engineering. He specialises in the areas of fluid-borne noise measurement and reduction in hydraulic fluid power systems, active noise control, numerical modelling of hydraulic components, unsteady turbulent flow, pipeline and hose dynamics.

Nigel Johnston studied the measurement and prediction of pressure ripple in hydraulic systems for his PhD. This work has since been used as the basis for an ISO Standard for the measurement of pump pressure ripple characteristics. He was appointed Lecturer in 1990 and Senior Lecturer in 2003.

He has supervised 18 PhD students to completion.

He regularly teaches on industrial fluid power courses in the UK, Europe and USA. He is Organiser and joint Editor for the Bath/ASME International Fluid Power and Motion Control Symposium.


Nigel Johnston has over 30 years’ experience in hydraulic fluid power research and teaching. He obtained his PhD for research into fluid-borne noise characteristics of hydraulic systems. This work has since been used as the basis for an ISO Standard for the measurement of pump pressure ripple characteristics.

He has also been involved in research into: active noise control, cavitation, numerical modelling of fluid power components, unsteady turbulent flow, pipeline and hose dynamics, pump condition monitoring, vehicle steering dynamics and aircraft fuel systems. He has published about 100 refereed journal and conference papers and has collaborated with several companies including Delphi Steering Systems, General Motors, Airbus, John Deere, Sun Hydraulics, Parker Hannifin and BMW.

He recently led a large research project looking into efficient fluid power systems, funded by EPSRC with industrial collaboration. In most hydraulic fluid power systems, valves are used to throttle the flow and reduce the hydraulic pressure. This is a simple but extremely inefficient method as the excess energy is lost as heat, and it is common for more than 50% of the input power to be wasted in this way. Novel methods are being investigated for increasing the efficiency of hydraulic systems whilst maintaining performance, cost-effectiveness, reliability and low noise. The potential for improvement is huge. Reducing power consumption will contribute to the UK Government's commitment to cutting carbon dioxide emissions. However there are significant challenges.

Teaching units

  • Modelling Techniques II
  • Mechanical Vibrations and Noise
  • Fluid Power


Read publications by Nigel Johnston