Nonlinear dynamic response of floating circular cylinder with taut tether

Tethered floating circular cylinder can be regarded as a typical simplified model in offshore engineering. Such structure is the basic component of TLP. Careful investigation on the dynamic response of this type of cylinder may give a hint on some new nonlinear characteristics of TLP, which have been omitted before. Then the nonlinear dynamic analysis of a tethered cylinder is performed in the time domain. Nonlinearities considered in the analysis include geometric nonlinearity induced by coupled finite translational and rotational displacements of the cylinder, nonlinear hydrostatic and inviscid hydrodynamic forces introduced by the effect of instantaneous wet surface, and the velocity squared viscous drag force (also integrated to instantaneous wet surface). Numerical results are presented which illustrate that rotations exert a significant influence on the dynamic motion responses of the tethered cylinder, and should be dealt with as finite variables instead of infinitesimal.