279
Chapter 20
An Italian Twist on
an Americas Cup
Sailboat Hull Design
Raffaele Ponzini and Andrea Penza
20.1 INTRODUCTION
To win the America’s Cup [1], one must defeat the other teams not only
in regattas but also in design studies, a strongly technological challenge
where a major role is covered by computational uid dynamics (CFD).
As is common in most computer-aided engineering (CAE) industrial
applications, soware licenses are a major cost item; moreover, it is
well known that in-silico data acquisition (i.e., data obtained from
computational models) is becoming the elective environment for the
design development process, involving multiphysics CAE tools and a
dramatic increase in requested high-performance computing (HPC)
resources. As a byproduct, budgets related to “computing” activities are
increasingly at risk of becoming the real bottleneck in the technological
challenge. Open-source CFD soware might become a key point to
CONTENTS
20.1 Introduction 279
20.2 Adoption of HPC: Insights into Portability and Scalability 280
20.3 HPC Performance Evaluation and Benets 282
20.4 Future Developments 282
References 283
280 Industrial Applications of High-Performance Computing
overcome such a bottleneck; nevertheless, large campaigns are required
to validate digital models against physical models to ensure reliability
for industrial-use cases of interest. e problem is complex in its entirety
and it is crucial to have access to advanced computing resources that are
able to process the large amount of data produced by such design studies
considered as a whole and by each single numerical simulation. For this
purpose, the design team of the Luna Rossa Challenge [2], besides taking
advantage of large amount of HPC resources for design data production,
both in terms of computing and remote visualization, undertook
with CINECA in 2012, a 12-month feasibility study evaluating the
OpenFOAM (Open Source Field Operation and Manipulation) toolbox
[3].
20.2 ADOPTION OF HPC: INSIGHTS INTO
PORTABILITY AND SCALABILITY
e validation project presented herein has been designed to study
both state-of-the-art AC72 hulls, those that ended up competing in the
San Francisco Bay waters in August 2013, and well-known benchmark
hulls, fully validated through computational tools and towing tank
experiments. To provide fruitful answers, we tested both the accuracy
of the open-source solution against other commercial CFD codes and
its computational eciency concerning the time-to-solution at dierent
degrees of parallelism.
As a rst attempt, we studied the hull hydrodynamic of a reference hull
known in literature as DTMB–5415, a model conceived by the U.S. David
Taylor Model Basin (DTMB) in the early 1980s as a preliminary design
for a surface combatant ship with a sonar dome bow and transom stern.
For intellectual property reasons, all the results detailed in this article
concern this hull type. Suce to say that we found that the same general
conclusions may be applied also to the racing hulls in design.
e Navier–Stokes physics equations that govern the motion of uids
are particularly complex to solve. Only in very rare cases, and with simpli-
ed geometry and conditions, is it possible to obtain an analytical solu-
tion. erefore, digital numerical methods are considered the only feasible
way to solve such complex equations in real-life geometry and ow con-
ditions. e library used for this validation work, OpenFOAM, is based
on breaking down, or discretization, of the problem obtained through
the so-called nite-volume method. e equations are strongly nonlinear
and coupled, which makes the search for a solution even more complex,

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