Unsteady RANS CFD Simulations of Sailboat’s Hull and Comparison with Full-Scale Test

Pietro Casalone,Giuseppe Giorgi,Sergej Antonello Sirigu,Giuliana Mattiazzo,Oronzo Dell’Edera,Beatrice Fenu

doi:10.3390/jmse8060394

Abstract

The hydrodynamic investigation of a hull’s performance is a key aspect when designing a new prototype, especially when it comes to a competitive/racing environment. This paper purports to perform a fully nonlinear unsteady Reynolds Averaged Navier-Stokes (RANS) simulation to predict the motion and hydrodynamic resistance of a sailboat, thus creating a reliable tool for designing a new hull or refining the design of an existing one. A comprehensive range of speeds is explored, and results are validated with hydrodynamic full-scale tests, conducted in the towing tank facility at University of Naples Federico II, Italy. In particular, this work deals with numerical ventilation, which is a typical issue occurring when modeling a hull; a simple and effective solution is here proposed and investigated, based on the phase-interaction substitution procedure. Results of the computational fluid dynamic (CFD) campaign agree with the experimental fluid dynamic (EFD) within a 2% margin.

Highlights

The design of a new sailboat prototype is complex and requires time, experience, and resources
The K-epsilon model is recommended in volume of fluid (VOF) simulations as the computational cost is low and the accuracy in the discretization of the interface between the two phases is good enough [31,34]
Numerical Reynolds Averaged Navier-Stokes (RANS) simulation represents an accurate mean for the test of a new hull and can be useful during the boat design and testing process

Summary

Introduction

The design of a new sailboat prototype is complex and requires time, experience, and resources. Most of the time, it is not possible to simulate the real-scale experiment because the cost of realizing a full-scale model is usually prohibitive and, most importantly, towing tanks have limitations for the maximum beam, length, and velocity that can be tested in order to avoid blockage effects and wave reflection [3]. This means that once the analysis is completed, results must be scaled, potentially introducing errors [4].

Properties of Atka during the Midwinter Race

The Towing Tank of Naples University

CFD Model

Turbulence and Law of the Wall

Findings

Conclusions