Virtual Replica of a Towing Tank Experiment to Determine the Kelvin Half-Angle of a Ship in Restricted Water

Momchil Terziev,Tahsin Tezdogan,Zhiming Yuan,Guangwei Zhao,Atilla Incecik

doi:10.3390/jmse8040258

Momchil Terziev, Tahsin Tezdogan + Show 3 more

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https://doi.org/10.3390/jmse8040258

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Abstract

The numerical simulation of ship flows has evolved into a highly practical approach in naval architecture. In typical virtual towing tanks, the principle of Galilean relativity is invoked to maintain the ship as fixed, while the surrounding water is prescribed to flow past it. This assumption may be identified, at least partly, as being responsible for the wide-scale adoption of computational solutions within practitioners’ toolkits. However, it carries several assumptions, such as the levels of inlet turbulence and their effect on flow properties. This study presents an alternative virtual towing tank, where the ship is simulated to advance over a stationary fluid. To supplement the present work, the free surface disturbance is processed into Fourier space to determine the Kelvin half-angle for an example case. The results suggest that it is possible to construct a fully unsteady virtual towing tank using the overset method, without relying on Galilean relativity. Differences between theoretical and numerical predictions for the Kelvin half-angle are predominantly attributed to the assumptions used by the theoretical method. The methods presented in this work can potentially be used to validate free-surface flows, even when one does not have access to experimental wave elevation data.

Highlights

Computational fluid dynamics (CFD) has become widely accepted as a useful tool to predict the flow around a ship
The number of cells or, more generally, the computational effort required to perform a numerical simulation in model-scale is not thought to be prohibitive for practical applications
Regardless of the advances in every field of numerical modelling, CFD is not yet considered a replacement of model-scale experimentation. This is because it is not possible to guarantee that a particular numerical model will perform with the same level of accuracy across all possible case studies

Summary

Introduction

Computational fluid dynamics (CFD) has become widely accepted as a useful tool to predict the flow around a ship. This is facilitated by the increase in available computational power, which has allowed practitioners to re-create the flow around a vessel even on a standard computer. Regardless of the advances in every field of numerical modelling, CFD is not yet considered a replacement of model-scale experimentation. This is because it is not possible to guarantee that a particular numerical model will perform with the same level of accuracy across all possible case studies. Results with accuracy of a few percentage error can be found in the open literature [1,2,3,4,5,6,7]

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