On the numerical accuracy of the wave load distribution on a ship advancing in short and steep waves

Abstract

Defining numerical uncertainty is an important part of the practical application of a numerical method. In the case of a ship advancing in short and steep waves, little knowledge exists on the solution behaviour as a function of discretisation resolution. This paper studies an interfacecapturing (VOF) solution for a passenger ship advancing in steep (kA = 0.24) and short waves (L w /L pp = 0.16). The focus is to estimate quantitative uncertainties for the longitudinal distributions of the first-third harmonic wave loads in the ship bow area. These estimates are derived from the results of three systematically refined discretisation resolutions. The obtained uncertainty distributions reveal that even the uncertainty of the first harmonic wave load varies significantly along the ship bow area. It is shown that the largest local uncertainties of the first harmonic wave load relate to the differences in the local details of the propagating and deforming encountered waves along the hull. This paper also discusses the challenges that were encountered in the quantification of the uncertainties for this complex flow case.

Computational and experimental study on local ship loads in short and steep waves

“…This study continues our previous work in [17]. The previous work has focused on quantifying the numerical uncertainty of the loading in terms of the harmonic components of the force distribution in the bow area.…”

“…1 and the case parameters in Table 1. We have studied this case and another similar one previously in [17][18][19].…”

“…In general, the solution should be in the vicinity of the asymptotic range when quantifying uncertainties. In the case of ship wave loads, reaching the asymptotic range is a challenge even for the lowest harmonic components, although quantified uncertainties have been presented for mean and first harmonic global loads in [5,6,14,16] and for the 1st-3rd harmonic components of the vertical force acting on a ship frame in [17]. The qualitative solution behaviour of ship wave loads has been studied in [2,4,10].…”

“…The previous work has focused on quantifying the numerical uncertainty of the loading in terms of the harmonic components of the force distribution in the bow area. As such, the paper [17] focused on the numerical behaviour of the solution only. This paper studies the validity of the flow behaviour predicted by the numerical method.…”

Manufacturing and design of the offshore structure Froude scale model related to basin restrictions

“…CFX analysis is able to determine model forces, moments and displacements in regular waves. CFX-Pre module can model input parameters of the analysis as required [2]. Based on the results of CFX-Post module we can view and measure the results for static mechanical analysis on the scale model.…”