Department of Mechanical Engineering

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For further information about Prasp, please contact Dr Nigel Johnston

Tel: +44 (0) 1225 38 3026


Prasp - hydraulic fluid-borne noise modelling software

Prasp (`Pressure Ripple Analysis Software Package') is a MATLAB/Simulink® toolbox to model or simulate the fluid borne noise (FBN) characteristics of hydraulic circuits. FBN is pressure and flow pulsations or ripple.

Areas of application include: automotive power-assisted steering, mobile machinery, aerospace, marine, industrial hydraulics. Noise is often a serious problem in any of these applications, and Prasp provides a powerful tool for analysis and design of low-noise systems.

Prasp includes mathematical models for most common hydraulic components. The user can also create new models if necessary. In addition to the mathematical models, components may also be represented using spectral data read from files. These files are compatible with experimental results processed using the FBN package (available from the University of Bath). Circuits can be built up using experimental data, mathematical models or a combination of the two.

Prasp circuit models are not solved in the same way as normal Simulink models, but a separate MATLAB solver and graphical post-processor is provided with the Prasp toolbox. Prasp operates in the frequency domain.

Results can be plotted as pressure ripple, flow ripple, impedance or pressure ratio. Transmission loss and transfer matrices can also be calculated. Frequency and parametric sweeps can be performed. For example, this graph shows the transmission loss of an expansion chamber for different diameters and frequencies.


  • Clear hydraulic circuit diagrams
  • User-defined models
  • compatible with measured component data
  • parametric sweeps for system optimisation
  • advanced models for flexible hoses, including 'tuner' insert.

Fluid system simulation             Fluid system simulation


Please enquire about availability and price of Prasp licenses for commercial use.

Alternatively, analysis can be performed on a consultancy basis at the University of Bath, where we have a wealth of experience in the measurement and modelling of fluid-borne noise and interpretation of results.