Experimental and numerical estimation on roll damping and pressure on a 2-D rectangular structure in free roll decay test

Abstract

Experimental and numerical studies were performed to estimate roll damping and hydrodynamic pressure on a 2-D rectangular structure. Free roll decay test was simulated by experiment in 2-D wave tank with Particle Image Velocimetry (PIV) measurement, and by numerical simulations using CFD based on an unsteady incompressible Reynolds-Averaged Navier-Stokes (RANS) approach. The dynamic characteristics of the roll motion and the roll damping coefficients from the experiment and CFD were analyzed and compared. Velocity and vorticity fields obtained from the PIV measurement were examined to understand the fluid fields in the vicinity of the structure and compared with them from CFD to validate the numerical methods applied in the study. The PIV-based pressure estimation method was applied to predict pressures on the structure, and results were compared with them from CFD to assess the feasibility of the PIV-based estimation approach. The overall agreement between experimental and CFD results was good for roll damping coefficient, velocity and vorticity fields, and pressure considering the complexity of fluid physics in the roll motion. It was found that the PIV-based pressure estimation method would be alternative technique to estimate the pressure and loads on the structure.