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Numerical Comparison between a Modern Surfboard and an Alaia
Board using Computational Fluid Dynamics (CFD)
Luca Oggiano
Norwegian University of Science and Technology – SIAT (Senter for Idrettsanlegg og Teknologi),
K. Hejes Vei 2b 7042, Trondheim, Norway
IFE -Institutt for Energiteknikk, Instituttveien 18a, 2007, Kjeller, Norway
Keywords: Hydrodynamics, CFD, Surfboard Design.
Abstract: Surfboard design is traditionally considered more as an art than an engineering process. However, in the
past decade, the use of computers is becoming the standard in the shaping process. In the design part the use
of computer-aid-design (CAD) software, has simplified the design process allowing shapers to save time
and consistently modify or reproduce similar designs. At the same time, the improvement of computer-
numerical-controlled (CNC) machines is slowly replacing the traditional hand shaping techniques with more
controlled and reproducible manufacturing process. Another considerable advantage about having a 3D
CAD model of the surfboard is that the model can be imported in Computational Fluid Dynamics (CFD)
programs and its performances can be studied and evaluated highlighting details that would be otherwise
impossible to identify from a field test. The present paper aims to show the potential of CFD solvers for
surfboard design and its applicability by comparing a modern surfboard with a traditional ancient surfboard
design (alaia). The performances of the modern surfboard are evaluated and compared with the alaia board,
represented by an equivalent flat plate which is also used for validation. The commercial CFD code STAR-
CCM+ is used in the present work. An Unsteady Reynolds Navier Stokes (URANS) approach is used, the
volume of fluid (VOF) method is chosen as free surface discretization method and the turbulence model
chosen to allow the numerical closure of the RANS equations is the k-ɷ-SST proposed by Menter. The
model validation on an alaia board, represented as a flat plate shows good agreement with previous studies
and the comparison between the surfboard and the alaia addresses the superiority of the modern surfboard
design in terms of stability.
1 INTRODUCTION
Surfboards firstly appeared in the 5
th
-6
th
century in
Hawaii and they were used monarchs and villagers
alike. At that time, three types of surfboards were
available: the paipo (used by children) the olo (long,
thick and heavy boards that could weight up to
100kg) and the alaia. Surfing as we know it
(standing up and riding curing waves) was
developed and discovered thanks to the alaia boards.
The alaia boards are middle sized boards, simple in
shape, made in wood and finless, they can be
resembled to flat plates with a rounded nose. The
board paddles well enough to catch unbroken swells
still allows manoeuvres and curves on the waves
face and it is responsive to the surfer commands. For
centuries, surfing and surfboard design was confined
to Hawaii and no evolutions in the shape of the
boards were made since modern times. For the first
time, in 1930’s balsa wood (much lighter than
normal wodd) was introduced, the tail of the boards
were tapered to have a more hydrodynamic design
and increase manoeuvrability and fins were firstly
introduced to increase stability . The main change in
construction and materials didn’t appear since the
late 1940’s, where fiberglass was introduced,
allowing more complex shaping and finally driving
the design to the modern surfboard design
(Warshaw, 2010, Heimann, 2010). During this
period of time, boards became lighter, smaller and
their shape constantly evolved. However, the
surfboard design and shaping is still seen as a form
of art more than an engineering task.
Surfboards can be considered as 3D planing
surfaces similar to planing boats, velles, and surface
effect ship (SES) (Doctors, 2009). The main
Oggiano L.
Numerical Comparison between a Modern Surfboard and an Alaia Board using Computational Fluid Dynamics (CFD).
DOI: 10.5220/0006488400750082
In Proceedings of the 5th International Congress on Sport Sciences Research and Technology Support (icSPORTS 2017), pages 75-82
ISBN: 978-989-758-269-1
Copyright
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2017 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved