Hydrodynamics & drag predictions to assess propulsion needs - 12 August 2012

Hydrodynamics & drag predictions to assess propulsion needs

Norton Straw Consultants has been working with a customer to assess the power requirements for a remote operated vehicle (ROV). 

Initially starting out with engineering calculations and later progressing to the use of computational fluid dynamics (CFD), Norton Straw used predictions of the vessel's drag to assess the required thrust for the vessel to meet its design performance requirements. 

Initial hand-calculations were performed using DNV recommended practice.  However, uncertainty in the drag coefficient selected in this approach led to the application of CFD.

CFD simulation, using CD-adapco's STAR-CCM+ software, provided a method for predicted the drag coefficient of the vessel.  The CFD calculations demonstrated that the vessel's drag coefficient was significantly lower than could have been justified using primitive shapes or engineering principles. 

The findings from the CFD study removed conservatism from the initial drag coefficient estimates providing a much improved assessment of the propulsion requirements of the vessel thus demonstrating the value that can be gained from computational simulation in marine applications. 

CFD may be used further to help better understand the:
accelerative power required due to the added mass of the vessel using CFD
optimised thruster locations
pressure distribution on the vessel for optimised sea-keeping performance
overall hydrodynamic performance of the vessel

Note: Image shown is for illustrative purposes only and is not the vessel considered in this project

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