Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Numerical Study of The Effect of Wing Flexibility on Hydrodynamic Performance of An Underwater
Glider
Xiangcheng Wu1, Pengyao Yu1*, Wenting Wang2, Guangzhao Li1, Yanzhi Pan1
1College of Naval Architecture and Ocean Engineering, Dalian Maritime University, Dalian City, Liaoning Province, China
2No.703 Research Institute Of China State Shipbuilding Company Limiteo, Harbin City, Heilongjiang Province, China

ABSTRACT
Underwater gliders are winged, autonomous underwater vehicles that arebroadly applied in physical and biological oceanography. The wings
have an important impact on the hydrodynamic performance of theunderwater glider. In this paper, the effect of wing flexibility onhydrodynamic performance of an underwater glider is studied bycomputational fluid dynamics (CFD) methodology. The results showthat the wing deformation will reduce the lift force, drag force and pitch
moment of the underwater glider. The larger the Young’s modulus of thewing, the smaller the influence of the wing flexibility on thehydrodynamic performance of the underwater glider.

KEY WORDS: Underwater glider; wing flexibility; fluid-structureinteraction (FSI).

INTRODUCTION
An underwater glider is a special type of autonomous underwater vehicle
which is controlled by adjusting its buoyancy. For the characteristics of
low energy consumption, low cost and long range, several typicalunderwater gliders have been developed and broadly applied in physicaland biological oceanography, such as Slocum (Webb, 2001),Spray(Sherman, 2001) and Seaglider(Eriksen, 2001).
Underwater gliders move in the horizontal plane through thehydrodynamic force acting on the wings. Therefore, the wings greatly
affect the hydrodynamic characteristics of underwater gliders. And somescholars have studied these effects. Fan and Woolsey (2013) studied theeffect of a few geometric parameters on the steady wings-level gliding
and steady spiral motion of a glider. The conclusions include the fact thatusing smaller wingspans can attain to higher speed but smaller lift-dragratio. Positioning the wings father aft can improve the stable of theglider’s longitudinal dynamics. Liu (2014) studied the impact of winglayout on the movement efficiency and stability of a hybrid underwater
glider by orthogonal test. The results show that the chord length is themost important influence factor to the lift-drag ratio and the sweep angle
has the most significant impact on the stability of the glider. Javaid (2017)1111

investigated the effect of two different wing forms on the hydrodynamic
performance by experimental and numerical methods. The results showthat the glider with the rectangular wings has 15% more drag force and
17% more lift force than the glider with tapered wings when the pitch
angle is 12°. Shankar and Vijayakumar (2020) discussed the effect ofwing position on the glider’s lift and drag characteristics bycomputational fluid dynamics (CFD) methodology. The study brings outthat positioning the wings at the farthest point aft improves thehydrodynamic performance of the glider. The lift-drag ratio of the glider
with wing position farther aft is 6% higher than that of the glider withthe position at the forward of the glider when the attack angle is ±8°.
The effect of wing geometric parameters and position on thehydrodynamic performance has been studied. However, the wings
usually undergo certain elastic deformation due to hydrodynamic force
when the glider moves. There is no doubt that the deformation willchange the hydrodynamic performance of the glider. To our knowledge,
previous studies usually regarded the wing as rigid body and the effectof wing deformation on hydrodynamic performance of glider has notbeen fully investigated. In this paper, the effect of wing flexibility onhydrodynamic performance of an underwater glider is studied by CFD
method. The wing deformation are calculated by numerical simulationsof fluid-structure interaction (FSI). The results can provide a reference
for the design of underwater glider wings.
The rest of the paper is organized as follows. Section 1 introduces thenumerical model and discusses the accuracy of the present numericalmodel. Section 2 analyses the effect of wing flexibility on hydrodynamic
performance of an underwater glider. Finally, the main conclusions aresummarized.

Numerical model
Governing Equations
The commercial CFD software STAR-CCM+ is employed to solve theflow field and the deformation of the wings. The flow is assumed to beincompressible and solved by calculating the transient Reynolds
Averaged Navier Stokes (RANS) equations expressed as follows:(1) u f = 0