Numerical Methods to Predict Hydroelastic Response of Ships in Extreme Seas
Thomas E. Schellin
To assess structural integrity of ship hull structures in extreme seas, hydroelastic effects have become important because they contribute to life cycle load spectra of wave-induced hull girder stresses. To numerically predict these effects, Reynolds-averaged Navier-Stokes (RANS) equations were coupled with nonlinear rigid body motion equations of the elastic ship hull. Three containerships in regular waves, in random irregular long-crested waves, and in deterministic wave sequences were numerically investigated. Computations and comparative experimental measurements correlated favorably. The different wave models comprised second order Stokes waves and wave fields obtained from the solution of the nonlinear Schrödinger equation. This equation has a number of exact analytical solutions, known as breathers, which are prototypes of rogue waves. Such waves are relevant because they may emerge spontaneously from a random seaway, provided the spectrum is sufficiently narrow and waves, on average, are sufficiently steep. Numerical simulations in random irregular waves provided short-term ship response probabilities in extreme seas relevant for design.