Abstract:

An experimental study has been conducted of forces on a cylinder in a standing acoustic wave. The cylinder is representative of the leg of an offshore structure or platform, while the acoustic field is representative of the oscillatory wave loading on such a structure. A piston oscillator drive mechanism provides the requisite large acoustic amplitudes in the pressure vessel resonator that houses the test cylinder. The use of a high-pressure gas allows the desired high values of the Reynolds numbers to be achieved. Both in-line drag forces and transverse (lift) forces on the cylinder, along with the phasing information, have been measured with the help of suitably mounted strain gauges, and corroborated with existing data in the literature. Higher harmonic forces and resonant interactions, typical of compliant structures, have also been measured and analyzed. This experimental technique appears to have a promising potential for studying the large amplitude, large Reynolds number regime of hydrodynamic loading and the resulting fluid--structure interactions.