Drag Forces and Flow-Induced Vibrations of a Long Vertical Tow Cable—Part I: Steady-State Towing Conditions

Abstract

The analysis of data from a unique experiment on the quasistatics and vortex-induced dynamics of a long vertical tow cable is presented. The experiment consisted of measuring simultaneously the vortex-induced motions and the steady-state configuration of a tow cable. The measured steady-state configuration of the cable was used to calculate the cable’s average drag coefficient which ranged from 2.2 to 2.5. It was observed that the vortex-induced motion of the cable was modulated by a beat due to the presence of a shear current. This is confirmed here by spectral and time domain analysis of the acceleration records. The rms motion of the cable varies with depth, which indicates that the drag coefficient of the cable is spatially varying.