Experimental study on vortex induced vibrations of highly flexible immersed pipe subjected to top end oscillations

This study reports an experimental investigation on vortex induced transverse vibrations of a highly flexible free hanging pipe. The experiment was carried out in a towing tank with a 6 m of long flexible rubber pipe, by exciting top end oscillations and measuring lateral displacements at nine points. The largest response amplitude of transverse vibrations occurs at the bottom part of the model for all excitation frequencies and amplitudes. Even though Kc numbers are different along the model length due to in-line response amplitude differences, transverse vibration frequencies are all the same along the model length. Transverse structural wave propagation is observed at the experiment and found in the measured data analysis. A transverse structural wave initiated at a particular point by vortex shedding propagates along the model length and resulting in all the response frequencies to be same.