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was derived from the parameters of the incident wave. The results of approximate solution are shown in Fig.8 by solid lines, the experimental values are denoted analogously to Fig.7. The experimental conditions are given in Table 1.

The agreement between the predicted and measured loads is better for the horizontal component as compared to the vertical component what is especially notable at high wave frequencies. In general, the results of this series of computations give better fit to the experimental data at low frequency (large length) of incident waves what is consistent with the physical assumptions used in the formulation of the approximate solution.

4.
CONCLUSIONS

This study is among the first attempts to determine the diffraction loads induced by internal waves on restricted horizontal elliptic cylinder in the case of continuous pycnocline stratification. It is shown that the presence of a finite layer of variable density changes the character of wave loading compared to the case of two-layer fluid with a step change in density.

The comparison between the experimental data and the computations reveals that the vertical force is essentially overestimated by the linear theory. There are reasons to believe that this departure results from non-linear effects. The elliptic shape of cross-section implies different conditions for separation depending on orientation of the cylinder in the flow.

In future, it would be desirable to continue the investigation of internal wave scattering with the study on role of the shape of cylinder cross-section and refined account of effects conditioned by continuous stratification.

ACKNOWLEDGMENT

This work was made possible in part by Grant No. JHX 100 from International Science Foundation and Russian Government.

REFERENCES

1. Phillips, O.M., ”The Dynamics of the Upper Ocean,” 2nd ed. Cambridge Univ.Press, Cambridge e.a., 1977.

2. Miropolsky, Yu.Z., ”Dynamics of Internal Gravity Waves in the Ocean,” Gidrometeoizdat, Leningrad, 1981 (in Russian).

3. Ermanyuk, E. & Sturova, I., ”Effects of Regular Waves on the Body Submerged in a Stratified Fluid, ” 20th Symposium on Naval Hydrodynamics, Santa Barbara, Calif., USA, Aug. 1994, pp.232–246.

4. Razumeenko, Y.V., ”Changeability of Hydro-physic Ocean Fields; Problems of Manoeuvrability of Submerged Objects in Real Ocean,” International Symposium on Ship Hydrodynamics, St.-Petersburg, Russia, 1995, pp. 275–288 (in Russian).

5. Sarpkaya, T.,” Forces on a Circular Cylinder in Viscous Oscillatory Flow at Low Keulegan-Carpenter Numbers,” Journal of Fluid Mechanics, Vol. 165, Apr. 1986, pp.61–77.

6. Chaplin, J.R., ”Wave Forces on a Horizontal Cylinder Beneath Waves,” Journal of Fluid Mechanics, Vol. 147, Oct. 1984, pp. 449–464.

7. Kochin, N.E., Kibel, I.A., Rose N.V. ”Theoretical Hydromechanics”, Fizmatgiz, Moskva, P. 1, 1963 (in Russian).

8. Sturova, I.V., ”Scattering of Surface and Internal Waves on Submerged Body,” Computational Technology, Novosibirsk, Vol. 2, No. 4, 1993, pp.30–45 (in Russian).

9. Sturova, I.V., ”Effect of Anomalous Dispersion Dependences on Scattering and Generation to Internal Waves,” Journal of Applied Mechanics and Technical Physics, Vol. 35, No. 3, Nov. 1994, pp.366–372.



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