On the Difference Between Methods of Calculating the Neumann-Kelvin Wave Resistance

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Authors
  1. Hally, D.
Corporate Authors
Defence R&D Canada - Atlantic, Dartmouth NS (CAN)
Abstract
In the Neumann-Kelvin formulation of flow around a ship hull with a free surface, one can calculate the wave resistance using two different methods: Havelock's formula, which is an estimate of the resistance obtained from the radiated waves in the far field; and integration of the pressure over the hull. For a typical vessel, there is usually a discrepancy of the order of 20% in the two predictions. An analysis of the momentum flux through a control volume enclosing the hull shows that the linearized free surface boundary condition allows the leakage of momentum through the free surface. Some of the momentum imparted to the fluid by the hull is lost through the free surface, so the resistance calculated using the Havelock formula is lower, for Froude numbers less than about 0.5, than the resistance calculated by integrating the pressure over the hull. It is not possible to say which method yields the more accurate predictions.

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Keywords
Ships;Resistance;Neumann-Kelvin problem;Havelock resistance formula;Panel methods;Dawson's panel method;POTFLO
Report Number
DRDC-ATLANTIC-SL-2005-135 — Scientific Literature
Date of publication
21 Sep 2005
Number of Pages
6
DSTKIM No
CA026549
CANDIS No
524437
Format(s):
Electronic Document(PDF)

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