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Removing the irregular frequencies from integral equations in wave-body interactions

Published online by Cambridge University Press:  26 April 2006

C.-H. Lee
Affiliation:
Department of Ocean Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
P. D. Sclavounos
Affiliation:
Department of Ocean Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA

Abstract

The paper presents a method that removes the effects of all irregular frequencies in boundary-integral equations governing the interaction of regular waves with floating bodies of general geometry. A modified integral equation is obtained by the linear superposition of the classical Green equation and its normal derivative with respect to the field point. The selection of a purely imaginary constant of proportionality ensures the removal of all irregular frequencies in the continuous problem and the appropriate selection of its magnitude eliminates their undesirable effects in its numerical implementation. Computations are presented of the added-mass and damping coefficients and exciting forces on a sphere and a truncated vertical cylinder, illustrating the effectiveness of the method.

Type
Research Article
Copyright
© 1989 Cambridge University Press

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References

Adachi, H. & Ohmatsu, S. 1979 On the influence of irregular frequencies in the time-dependent free surface problems. J. Soc. Nav. Arch. Japan 146, 119128.Google Scholar
Angell, T. S., Hsiao, G. C. & Kleinman, R. E. 1986 An integral equation for the floating body problem. J. Fluid Mech. 166, 161171.Google Scholar
Bai, K. J. & Yeung, R. W. 1974 Numerical solutions to free-surface flow problems. In Proc. 10th Symp. Nav. Hydrodyn., Cambridge, MA, pp. 609633.
Brakhage, H. & Werner, P. 1965 Uber das Dirichletsche Aussenraumproblem fur die Helmholtzsche Schwingungsgleichung. Arch. Math. 16, 325329.Google Scholar
Breit, S. R., Newman, J. N. & Sclavounos, P. D. 1985 A new generation of panel programs for radiation-diffraction problems. Proc. BPSS'85 Conf., Delft.
Burton, A. J. & Miller, G. F. 1971 The application of integral equation methods to the numerical solution of some exterior boundary-value problems. Proc. R. Soc. Lond. A 323, 201220.Google Scholar
Colton, D. & Kress, R. 1983 Integral Equation Methods in Scattering Theory. Wiley Interscience.
Euvrard, D., Jami, A., Lenoir, M. & Martin, D. 1981 Recent progress towards an optimal coupling of finite elements and singularity distribution procedures in numerical ship hydrodynamics. Proc. 3rd Intl Conf. Num. Ship Hydrodyn, Paris.
Frank, W. 1967 Oscillation of cylinders in or below the free surface of deep fluids. Rep. 2375. Naval Ship Res. and Dev. Center, Bethesda, MD.
Hess, J. L. & Smith, A. M. O. 1966 Calculation of non-lifting potential flow about arbitrary bodies. Prog. Aero. Sci. 8, 1138.Google Scholar
Hsiao, G. C. & Kress, R. 1985 On an integral equation for the two-dimensional exterior Stokes problem. Appl. Numer. Maths 1, 7793.Google Scholar
Hulme, A. 1983 A ring-source/integral-equation method for the calculation of hydrodynamic forces exerted on floating bodies of revolution. J. Fluid Mech. 128, 387412.Google Scholar
John, F. 1950 On the motion of floating bodies. II. Simple harmonic motions. Communs Pure Appl. Maths 3, 45101.Google Scholar
Kellog, O. D. 1929 Foundations of Potential Theory. Springer.
Kleinman, R. E. 1982 On the mathematical theory of the motion of floating bodies – an update. DTNSRDC Rep. 82/074.
Korsmeyer, F. T., Lee, C.-H., Newman, J. N. & Sclavounos, P. D. 1988 The analysis of wave effects on tension-leg platforms. OMAE Conf., Houston.
Kress, R. 1983 Minimizing the condition number of boundary integral operators in acoustic and electromagnetic scattering. NAM-Bericht Nr. 35, pp. 130.
Lee, C.-H. 1988 Numerical methods for the solution of three-dimensional integral equations in wave–body interactions. Ph.D. Thesis, Department of Ocean Engineering, MIT.
Leis, R. 1965 Zur Dirichletschen Randwertaufgabe des Aussenraums der Schwingungsgleichung. Math. Z. 90, 205211.Google Scholar
Martin, P. A. 1981 On the null-field equations for water-wave radiation problems. J. Fluid Mech. 113, 315332.Google Scholar
Mei, C. C. 1978 Numerical methods in water-waves diffraction and radiation. Ann. Rev. Fluid Mech. 11, 289316.Google Scholar
Moran, J. 1984 An Introduction to Theoretical and Computational Aerodynamics. Wiley.
Nestegard, A. & Sclavounos, P. D. 1984 A numerical solution of two-dimensional deep water wave–body problems. J. Ship Res. 28, 4854.Google Scholar
Newman, J. N. 1985 Algorithms for the free-surface Green functions. J. Engng Maths. 19, 5767.Google Scholar
Newman, J. N. 1986 Distributions of sources and normal dipoles over a quadrilateral panel. J. Engng Maths 20, 113126.Google Scholar
Ogilvie, T. F. & Shin, Y. S. 1978 Integral-equation solutions for time-dependent free-surface problems. J. Soc. Nav. Arch. Japan 143, 8696.Google Scholar
Ohmatsu, S. 1975 On the irregular frequencies in the theory of oscillating bodies. Papers, Ship Res. Inst., No. 48.
Panich, O. I. 1965 On the question of the solvability of the exterior boundary-value problems for the wave equation and Maxwell's equations. Russ. Math. Surv. 20, 221226.Google Scholar
Sayer, P. 1980 An integral-equation method for determining the fluid motion due to a cylinder heaving on water of finite depth. Proc. R. Soc. Lond. A 372, 93110.Google Scholar
Sclavounos, P. D. & Lee, C. H. 1985 Topics on boundary-element solutions of wave radiation-diffraction problems. In Proc. 4th Intl Conf. Num. Ship Hydrodyn., Washington.
Ursell, F. 1981 Irregular frequencies and the motions of floating bodies. J. Fluid Mech. 105, 143156.Google Scholar
Wehausen, J. V. & Laitone, E. V. 1960 Surface Waves. Handbuch der Physik, Vol. 9, pp. 446778, Springer.
Wu, X. J. & Price, W. G. 1987 A multiple Green's function expression for the hydrodynamic anatysis of multi-hull structures. Appl. Ocean Res. 9, 5866.Google Scholar
Yeung, R. W. 1973 A singularity-distribution method for free-surface flow problems with an oscillating body. Rep. NA 73-6, College of Engng, Univ. of Cal., Berkeley.