Hydrodynamic Design

The Indian Ocean tsunami which devastated 13 countries and killed more than 200,000 people in December 2004 was a chilling demonstration of the power of the hydrodynamic forces which are generated when a fluid flows over a solid object. Forces of lower magnitude are more common in the marine environment, but they may still be destructive or wasteful in the long term. For example:

• An increase of just 20 microns in the surface roughness of a ship’s hull will increase its hydrodynamic drag – and hence the fuel required to power it – by 1 or 2%. This equates to over 2 million tonnes of fuel wasted in a year, based on the world shipping industry’s annual fuel consumption of 170 million tonnes.


A fair hull reduces propulsive power requirements

• The hydrodynamic drag of an unfaired object – and hence the towing or mooring force – may be 40% higher than that of a similar streamlined shape.

High forces are required to tow a blunt body


• Vortex shedding from poorly designed underwater components causes unsteady hydrodynamic forces, leading to premature fatigue failure.

Expensive structures may suffer premature fatigue failure due to poor hydrodynamic design and exposure to high water flow velocities

Such problems can be avoided by careful consideration of the surrounding flow regime and appropriate hydrodynamic design.

Focus Offshore offers impartial consultancy and a practical design service for:

  • Hydrodynamic force analysis
  • Lift and drag predictions
  • Advice on drag reduction techniques
  • Control surface and appendage design
  • Hydrodynamic performance prediction, evaluation and optimisation
  • Experimental specification for physical modelling
  • Model testing, data processing and performance assessment
  • Procurement of cost-effective facility hire for hydrodynamic testing
  • Technical audits and appraisals
  • Provision of Computational Fluid Dynamics (CFD) flow analysis

Representative projects:

· Hydrodynamic design of underwater vehicles [download paper]
· Worldwide audit of hydrodynamic tests facilities for QinetiQ Haslar
· Design of control surfaces [download paper]
· Novel propulsion systems [download paper]
· Non-Intrusive Methods for Detecting Laminar-Turbulent Transition in Boundary Layer Flow


Hydrodynamic test facilities

Bottom row, from left:

Flow visualisation of a control surface tip vortex

Colour-coded results from acoustic detection of laminar/turbulent flow transition

Drag reduction in the design of an underwater vehicle

Tank tests to determine manoeuvring coefficients of an underwater vehicle