Non-Linear Numeric Parametric Roll Analysis for the DTMB 5512 in Regular Waves

Abstract

Parametric roll motion is a phenomenon that occurs within seconds, and it can reach high roll degrees.If the periodic stability of a ship changes, it may cause roll angles over 25 degrees, threatening the safety of the crew and the ship.This also threatens the operational skills of the ship.To investigate this phenomenon, a navy combatant model DTMB 5512 is selected.The model also has a bilge keel.Himeno's method was employed to calculate damping coefficients based on roll decay experiments (from literature) conducted at various model speeds and initial angles.This approach facilitated the extraction of both linear and non-linear damping coefficients from experimental data.Additionally, extinction coefficients were also obtained.Maxsurf stability software was utilized to compute GM values and generate the GZ curve.A Runge-Kutta method implementation in Python programming enabled numerical analysis, comprising a total of 240 simulations across 10 wave heights and 24-speed scenarios.For each scenario, the maximum roll angle was determined.It was observed that roll angles increased notably when the encounter frequency approached twice the natural roll frequency.Based on the analysis findings, maximum roll angles did not exceed 25 degrees, indicating that the DTMB 5512 model is not vulnerable to parametric roll resonance.