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 Simulation of Ship Model Self-propulsion in Shallow Water
Boao Cai1,2,3, Qing Xu1,2,3, Liaoyuan Qiu1, Binbin Tian1, Xiaofei Mao2,3, Jiangtao Qin2,3, Wei Chai2,3
1. China Ship Development and Design Center, Wuhan, Hubei, China.
2. School of Naval Architecture, Ocean and Energy Power Engineering, Wuhan University of Technology, Wuhan, Hubei, China.
3. Key Laboratory of High Performance Ship Technology (Wuhan University of Technology), Ministry of Education, Wuhan, Hubei, China.

errors (Lv et al., 2013). Recently, Lee et al. (2021) employed thedescriptive body force method to predict the self-propulsion performanceof a ship in regular waves, and the calculation time has been greatly
shortened. Different from the descriptive body force method, theiterative body force method has better performance in capturing thedetails of flow field (Choi et al., 2010). In this method, the propeller load
calculated by potential flow method is converted into a body force
distribution, which is then applied to the Reynolds-averaged Navier–Stokes (RANS) solver, and the flow fields of the propeller and the hullare iterated until convergence (Simonsen, 2005; Vaz and Bosschers,2006). In order to avoid errors caused by the BEM solver in the iterative
body force method, Qin (2014) calculated the flow fields of the propellerin the RANS solver. Recently, a new iterative body force method without
nesting iteration has been put forward and reduces the time of calculation(Guo et al., 2020). Feng et al. (2020) presented a modified Osaka
University Method (OUM) coupled with blade element momentum
theory (BEMT). Based on this method, the full-scale KCS free runningsimulation is further studied (Yu et al., 2021). Furthermore, the bodyforce method is widely used in the field of ocean engineering, such as
tidal turbines and water turbines (Turnock et al., 2011; Dominguez et al.,2016).
For ship self-propulsion in shallow water, larger hydrodynamic forces
are generated. In addition, ship-bottom and propeller-bottom interactions
are more obvious due to the blockage between the ship and the bottomof the waterway, which influence the navigation performance of the ship
(Liu et al., 2019). In recent years, the numerical prediction of the shallow
water effect is mainly focused on resistance, instead of the flow fielddetails. Most researchers explore the influence of water depth on the ship
resistance and the flow field characteristics by changing the depth of thenumerical tank (Sun et al., 2017). There are a lot of problems that needto be solved in numerical research on ship self-propulsion in shallow
water. On the one hand, the hydrodynamic forces acting on the hull andpropellers will increase, and the motion amplitude of the ship will also
increase, which will lead to longer calculation time to ensure the stabilityof calculation. On the other hand, the interaction between ship, propeller
and bottom makes the flow field more complex, which requires moregrids to capture. In order to solve these problems, it is of greatsignificance to introduce the body force method to ship self-propulsion
in shallow water.
The purpose of this paper aims to apply the descriptive body force
method to the shallow water. The commercial software, STAR-CCM+,

ABSTRACTIn numerical research of ship self-propulsion, the body force method iswidely used to save the computational resources. In this work, the bodyforce method is introduced to simulate the self-propulsion of the ship inshallow water. Specifically, the KVLCC2 model and the propeller model
are taken as research objects. The results of the body force method show
good agreement with the discretized propeller method in different water
depths. In addition, water depth influences the thrust deduction fraction
and the wake fraction significantly. The calculation results can provide abasis for the optimization of ship with low speed and large block
coefficient as well as for the propeller optimization in shallow water.

KEY WORDS: CFD; body force method; shallow water effect; ship
self-propulsion.

INTRODUCTION
Research of ship self-propulsion performance is of great significance tothe design of ships and propellers. Compared with model tests,
computational fluid dynamics (CFD) can not only reduce cost, but also
provide details of the flow field which are difficult to capture in the tests.
For numerical simulation, the discretized propeller method and the bodyforce method are widely used (Lübke, 2005; Hough and Ordway, 1964).
In order to capture the complex transient flow around a rotating propeller,
the discretized propeller method requires a great number of grids and asmall-time step. When the details of flow field are not the focus, the bodyforce method can be applied as an effective alternative method tosimulate self-propulsion. In this method, the real propeller is replaced bya virtual disk which can generate force and torque just like the propeller,
therefore, the computational efficiency can be greatly improved(ADAPCO, 2021). Based on the methods of obtaining the source term ofbody force, the body force method can be divided into the descriptive
body force method and the iterative body force method (Moctar, 2001;
Kawamura et al., 1997). In the descriptive body force method, the thrust
and the torque of the propeller are discretized in the virtual disk with aspecific distribution. The body force model proposed by Hough andOrdway (H-O) (Hough and Ordway, 1964) is the most widely usedmodel, and quite accurate results can be obtained even without
considering the torque (Wu et al., 2013). However, if the torque is notconsidered in the uniformly distributed body force model, it may cause

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