Time simulation of the motion of a tension leg platform

Paper in proceeding, 1988

The time-domain motion of a Tension Leg Platform is studied. The used method is based on a convolution technique in which the hydrodynamic reaction force from the frequency-domain solution is Fourier transformed to the time domain. Such a method allows one to consider arbitrary time varying external forces as for example non-linear reaction forces from tendons as well as transient loads. In the developed model time series of first-order wave forces and second-orde slowly varying wave forces are calculated for irregular plane and short-crested waves. Exciting forces due to wind and current are calculated using drag coefficients from model tests. The equations of motion in the time domain are solved for a tension-leg platform performing rigid body motion and results in time series of the motions as well as of the tension in the tendons. Numerical simulations have been carried out and the results are discussed. A comparison is made between calculations and model tests for a tension-leg platform in irregular long-crested waves.