Journal of Fluid Mechanics

Computer extension and analytic continuation of Stokes’ expansion for gravity waves

Leonard W.  Schwartz a1
a1 Department of Aeronautics and Astronautics, Stanford University, California 1

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Stokes’ infinitesimal-wave expansion for steady progressive free-surface waves has been extended to high order using a computer to perform the coefficient arithmetic. Stokes’ expansion has been found to be incapable of yielding the highest wave for any value of the water depth since convergence is limited by a square-root branch-point some distance short of the maximum. By reformulating the problem using a different independent parameter, the highest waves are obtained correctly. Series summation and analytic continuation are facilitated by the use of Padé approximants. The method is valid in principle for any finite value of the wavelength and solutions of high accuracy can be obtained for most values of the wave height and water depth. An alternative expansion procedure proposed by Havelock for the computation of waves short of the highest has been reconsidered and found to be defective.

(Published Online March 29 2006)
(Received April 25 1973)


1 Present address: N.A.S.A. Ames Research Center, Moffett Field, California.