Scipedia

Cianferra*, M.

Petris, G.

Armenio, V.

XI International Conference on Computational Methods in Marine Engineering
Hydroacoustic Pattern of Twin Propellers with Hull Interaction
M. Cianferra1,∗, G. Petris1 and V. Armenio1
1 Department of Engineering and Architecture
University of Trieste, Trieste, Italy
∗ marta.cianferra@dia.units.it
ABSTRACT
This study investigates the hydroacoustic patterns of
twin counter-rotating propellers, focusing on the in-
fluence of phase shifts between their rotations and the
effects of hull interaction on acoustic wave propaga-
tion. The analysis employs the Full Acoustic Anal-
ogy (FAA), a methodology previously developed by
Petris et al. (2022). The FAA integrates Large Eddy
Simulations (LES) to resolve the fluid dynamics,
the Ffowcs-Williams and Hawkings (FW-H) acous-
tic analogy (Ffowcs Williams and Hawkings, 1969)
to evaluate noise at specific observation points, and a
time-domain wave propagation model to reconstruct
the acoustic field in bounded domains.
The results emphasize the dipole nature of the noise
source and demonstrate that phase shifts between
the propellers significantly affect noise levels and
standing-wave patterns. Noise reduction or amplifica-
tion arises from the constructive or destructive inter-
ference of acoustic waves. Additionally, the presence
of the hull, modelled using the non-reflective hard-
source method (Lamonaca et al., 2024), introduces a
scattering effect that modifies both the amplitude and
directivity of the acoustic source. The study quanti-
fies the magnitude of this effect, highlighting its im-
portance in understanding and mitigating underwater
noise.
Furthermore, acoustic maps currently used to model
ship traffic noise typically rely on statistical models
that treat each noise source as a point-like emitter at
specific frequencies. This study demonstrates the de-
viation of the complete source here considered - com-
prising two propellers and the hull - from the simpli-
fied monopole model. The findings underscore the
necessity, particularly in shallow waters and confined
domains, to account for the source’s complexity to
achieve accurate noise predictions.
Figure 1: SPL of co-rotating twin propellers in unbounded
domain, synchronous case.
References
Petris, G., M. Cianferra, and V. Armenio (2022). Marine propeller noise propagation within bounded domains.
Ocean Engineering 265, p. 112618. DOI: https://doi.org/10.1016/j.oceaneng.2022. 112618.
FfowcsWilliams, J. E. and D. L. Hawkings (1969). Sound generation by turbulence and surfaces in arbitrary
motion. Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical
Sciences 264.1151, pp. 321–342.
Lamonaca F., Petris G., Cianferra M., Armenio V. (2024). Non-reflective hard source method for multi-
ple physically extended sources and scattering bodies. Physics of Fluids, 36 (3), art. no. 037115, DOI:
10.1063/5.0187929


Hydroacoustic Pattern of Twin Propellers with Hull Interaction

Scholcz*, T.

Serani, A.

 
Where Are We and Where Are We Going? Analyzing Simulation-Driven 
Design Optimization Trends in Marine Engineering by Scoping Review 
 
T.P. Scholcz1* and A. Serani2 
 
1Maritime Research Institute Netherlands (MARIN), Wageningen, The Netherlands 
e-mail: t.p.scholcz@marin.nl 
 
2National Research Council-Institute of Marine Engineering (CNR-INM), Rome, Italy 
e-mail: andrea.serani@cnr.it 
 
 
ABSTRACT 
In the marine/ocean engineering context, the demand for increasingly efficient products 
(e.g., hull-form, appendages, propellers, and offshore energy harvesting devices) is 
constantly increasing. These products must respond to an ever-increasing number of 
specific and complex requirements in order to improve on safety, sustainability, and a 
healthier environment. Over the last thirty years, engineering design, especially in the 
marine context, has radically transformed thanks to the exponential development of IT 
and digital resources. This stimulated the development of efficient simulation-driven design 
optimization (SDDO) methods, integrating CFD and design modification methods with optimization 
algorithms. There is an extensive body of literature describing state of the art SDDO approaches and 
research developments. In practice, the large scope makes it difficult to search and navigate the 
literature. Due to the complex and heterogeneous nature of the research, a scoping review helps to 
provide a map between the existing literature and characteristics of SDDO methods, see [1, 2]. This 
work answers the following questions: 
 
• What are the current best practices in using SDDO methods for marine engineering? 
• What issues arise when applying SDDO methods to marine engineering problems? 
• What are the main research gaps and possible future directions? 
 
For this purpose, the following steps are undertaken: 
1. Search and selection: paper identification, title/abstract screening and eligibility. 
2. Full text reading and characterization. 
3. Summary and synthesis. 
The scoping review may be used as a starting point for a systematic review in the future. This makes 
the review attractive, as it provides insight in the literature as well as a good basis for further study.       
  
REFERENCES 
[1] Serani, A, Scholcz, TP, Vanzi, V. A Scoping Review on Simulation-Based Design Optimization 
in Marine Engineering: Trends, Best Practices, and Gaps. Archives of Computational Methods in 
Engineering (2024). 
[2] Pham MT, Rajić A, Greig JD, Sargeant JM, Papadopoulos A, McEwen SA. A scoping review of 
scoping reviews: advancing the approach and enhancing the consistency. Res Synth Methods. 
2014 Dec;5(4):371-85. 


Where Are We and Where Are We Going? Analyzing Simulation-Driven Design Optimization Trends in Marine Engineering by Scoping Review

Zhou*, Y.

Cao, L.

Wan, D.

Study on the hydrodynamic performance of propellers in stratified
environments with temperature and salinity gradients
Yicheng Zhou1, Liushuai Cao1, Decheng Wan1*
1Computational Marine Hydrodynamics Lab (CMHL), State Key Laboratory of
Ocean Engineering, School of Ocean and Civil Engineering, Shanghai Jiao Tong
University, Shanghai, 200240, China
*Corresponding author. Tel.: +86 21 3420 5697; fax: +86 21 3420 5685.
E-mail address: dcwan@sjtu.edu.cn (D. Wan).
ABSTRACT
In the real oceanic environment, seawater exhibits stratification. The temperature, salinity,
and density of seawater all vary with depth. Among these, temperature and salinity are the
fundamental variables that jointly determine density and describe the basic properties of
seawater. They have significant impacts on mixing, turbulence, vortices, and other
phenomena, serving as crucial analytical indicators for conducting other marine research. This
study considers the dual influence of temperature and salinity on density, simulating a linearly
stratified flow field driven by both factors. Taking the MARIN 7371R propeller as the
research object, numerical simulations and studies were conducted on its propeller
performance in both homogeneous fluid and linearly stratified fluid influenced by the dual
factors of temperature and salinity, yielding the propeller's hydrodynamic parameters. A
comparison is drawn between stratified fluids and homogeneous fluids in terms of thrust
coefficient, torque coefficient, and open water efficiency, highlighting the unique properties
of stratified fluids. Furthermore, numerical simulations were conducted to evaluate the
hydrodynamic performance of the MARIN 7371R propeller in various temperature-salinity
fields. By comparing these three aspects of the propeller's performance, the impact of
different temperature and salinity on the propeller's performance was discussed.
Keywords: Stratified Fluid; Propeller; Open water characteristics;
References
Huang F, Meng Q, Cao L, et al. Wakes and free surface signatures of a generic submarine in
the homogeneous and linearly stratified fluid[J]. Ocean Engineering, 2022, 250: 111062.
Dogrul A. Numerical prediction of scale effects on the propulsion performance of Joubert
BB2 submarine[J]. Brodogradnja: An International Journal of Naval Architecture and Ocean
Engineering for Research and Development, 2022, 73(2): 17-42.
Pontarelli M, Martin J E, Carrica P M. Dynamic instabilities in propeller
crashback[C]//Proceedings of 5th International Symposium on Marine Propulsors. 2017.



Study on the hydrodynamic performance of propellers in stratified environments with temperature and salinity gradients

Smaoui, H.

Kaidi*, S.

 
 
XI International Conference on Computational Methods in Marine Engineering 
 
 
Numerical simulation of naval hydrodynamics by the LBM-IBM coupling 
 
 and S. Kaidi1 H. Smaoui1, *
 
 
1 Cerema Risks, Water and Sea  
34, Rue de Beauvais, 60280 Margny-lès-compiègne, France 
 
* Corresponding.Author:  hassan.smaoui@cerema.fr 
 
ABSTRACT 
 
 
The Lattice Boltzmann Method (LBM) is a recent numerical method compared to the classical approaches 
used to simulate fluid flow. Historically, it was presented in the 90s, to process gases on the lattice by cellular, 
and it could be seen as a particular discretization of the discrete velocity of the Boltzmann equation (BE), 
which describes the behavior of a fluid at a mesoscopic level. The LBM, which is based on the theory of 
statistical physics to solve numerically the BE. In this equation, the distribution of the different particles that 
compose a fluid is explicitly addressed in addition to the macroscopic quantities (speed, pressure, and density) 
[1]. For complex geometries, most LBM algorithms prove difficult to implement, but the Immersed boundary 
method (IBM)appears to offer a good practical compromise. 
The application of LBM to naval hydrodynamics begins to immerse in the community. The aim of this paper 
is to couple the LBM method with the solid boundary management strategy based on the immersed boundary 
method. To study the performance of this coupling, we simulate the hydrodynamic flow around a river boat. 
In particular the reproduction of the ripple waves. The results of the stimulations will be compared to those 
available in the literature, but also to those obtained experimentally. Finally, we try to apply the results of the 
model to the estimation of the bedload transport induced by the movement of the boats.  
 
References 
M. K. BANDA, M. SEAID AND G. THOMMES, Lattice Boltzmann simulation of dispersion intwo-
dimensional tidal flows, Int. J. Numer. Methods Eng., 77 (2009), pp. 878–900. 
 


Numerical simulation of naval hydrodynamics by the LBM-IBM coupling

Adam*, A.

Vogel, C.

Smyth, A.

XI International Conference on Computational Methods in Marine Engineering
Analysis of Wind Turbine Wake Meandering Using the Actuator Disc Model
Ali Ata Adam∗, Christopher R. Vogel and Amanda S.M. Smyth
Department of Engineering Science, University of Oxford, Oxford OX1 3PJ, UK
∗ ata.adam@eng.ox.ac.uk
ABSTRACT
The wind turbine wake, where the wind speed is re-
duced due to energy extraction by the turbine, is one
of the essential factors for evaluating energy produc-
tion in wind farms. The lateral and vertical low-
frequency oscillation of the wake, called wake me-
andering, causes a fluctuating loading on the down-
stream turbines, leading to increased fatigue and un-
even loadings (Larsen, 2022) and affects the overall
wind farm performance by impacting the wake recov-
ery (Hodgson et al., 2023). A key driving mechanism
of wake meandering is the amplification of upstream
disturbances (Gupta and Wan, 2019). The qualita-
tive impact of disturbances, such as the thrust force
(Medici and Alfredsson, 2008), turbine loading dis-
tribution (Dong et al., 2023), and inflow fluctuations
(Mao and Sørensen, 2018) on the dynamic wake char-
acteristics have been reported in the literature. How-
ever, quantifying the individual effects of these per-
turbations is challenging due to their complex interac-
tions, such as the coupling between turbulent inflow
and unsteady turbine loading.
This work aims to define and explore a well-defined
parameter space to isolate and quantify the effects
of the perturbations, such as turbine loading magni-
tude and distribution, on the wake instability, dynamic
wake characteristics and wake meandering parame-
ters. The study uses high-fidelity Large Eddy Sim-
ulations (LES) in OpenFOAM to capture the complex
unsteady flow features within the wake shear layer.
The wind turbine is modelled by an in-house actuator
disc model (ADM), allowing for a simplified and con-
trollable definition of parameters while preserving the
essential wake dynamics, as shown in Fig. 1. The
LES results are then analysed using the linear sta-
bility analysis method. This study provides insights
into wake stability and its relationship to wake re-
covery and turbulence intensity, which are expected
to advance our understanding of wake dynamics and
contribute to more accurate models for wind turbine
wakes and wind farm layout optimisation.
Figure 1: Normalised streamwise velocity on y=0 plane
around the actuator disc under a sheared inflow.
References
G. Dong et al. (2023). “Characteristics of wind turbine wakes for different blade designs”. Journal of Fluid
Mechanics 965, A15. doi:10.1017/jfm.2023.385.
V. Gupta and M. Wan (2019). “Low-order modelling of wake meandering behind turbines”. Journal of Fluid
Mechanics 877, pp. 534–560. doi:10.1017/jfm.2019.619.
E. L. Hodgson, M. H. A. Madsen, and S. J. Andersen (2023). “Effects of turbulent inflow time scales on wind
turbine wake behavior and recovery”. Physics of Fluids 35 (9), p. 95125. doi:10.1063/5.0162311.
G. C. Larsen (2022). “Wake Meandering”. Handbook of Wind Energy Aerodynamics. Ed. by B. Stoevesandt
et al. Springer International Publishing, pp. 955–1000. doi:10.1007/978-3-030-31307-4˙50.
X. Mao and J. N. Sørensen (2018). “Far-wake meandering induced by atmospheric eddies in flow past a wind
turbine”. Journal of Fluid Mechanics 846, pp. 190–209. doi:10.1017/jfm.2018.275.
D. Medici and P. H. Alfredsson (2008). “Measurements behind model wind turbines: further evidence of wake
meandering”. Wind Energy 11.2, pp. 211–217. doi:10.1002/we.247.


Analysis of Wind Turbine Wake Meandering Using the Actuator Disc Model

Kovacs*, G.

Shao, Y.

Bloom, R.

Walther, J.

CFD-based analysis and sensitivity study of a two-body
hinged raft wave energy converter
Gergely Kovacs1, Yanlin Shao1, Rune Pilgaard Bloom2 and Jens Honoré
Walther1
1 Technical University of Denmark, Department of Civil and Mechanical Engineering
gekov@dtu.dk, yshao@dtu.dk, jhwa@dtu.dk
2 Crestwing Aps, DK-9900 Frederikshavn, Denmark
rpb@crestwing.dk
Abstract
The two-body hinged raft  wave energy converters (WECs) offer significant
potential for harnessing ocean wave energy to generate electricity. Optimization of
these  devices  is  crucial  for  efficient  energy  conversion,  and  computational  fluid
dynamics  (CFD)  simulation  can  serve  as  a  pivotal  tool  since  nonlinear  wave
interactions  and  wave-structure  dynamics  can  be  simulated.  Validation  of  CFD
models for a 1:20 model-scale WEC from Crestwing will be shown with solutions to
address some of the challenges in CFD-based WEC simulations. For instance, the
calibration of a simplified damper model with time-varying damping to approximate
the highly nonlinear power take-off  (PTO) system, and the simulation of complex
motion using overset mesh technique with adaptive mesh refinement (AMR). The
numerical  results  correspond  appropriately  with  the  model  test  results  (3-10  %
difference in terms of absorbed power). Flow visualizations of the nonlinear effects
will be presented with a sensitivity study of mass, center of mass and width of the
device. These results contribute to the optimization of the WEC for a higher capture
width ratio (CWR) and a lower levelized cost of energy (LCOE).


CFD-based analysis and sensitivity study of a two-body hinged raft wave energy converter

Jiang*, Y.

Kelly, C.

Flatharta, D.

Sam-Daliri, O.

Flanagan, T.

Goggins, J.

Finnegan, W.

 
 
XI International Conference on Computational Methods in Marine Engineering 
 
 
Experimental Testing of Glass Fibre/Epoxy Resin Composite Bow Foil 
Demonstrators for Ships 
 
Yadong Jiang1,*, Coner Kelly2, Diarmuid Flatharta2, Omid Sam-Daliri1, Tomas Flanagan2, Jamie 
Goggins1, and William Finnegan1 
 
1 Construct Innovate and SFI MaREI Centre for Energy, Climate and Marine, Ryan Institute & 
School of Engineering, University of Galway 
University Road, H91 TK33 Galway, Ireland 
 
2 ÉireComposites Teo 
Údarás Industrial Estate An Choill Rua,Indreabhán, H91 Y923 Galway, Ireland 
* yadong.jiang@universityofgalway.ie. 
 
ABSTRACT 
Bow foils can reduce a ship’s CO2 emissions as they can 
reduce ship heave/pitch motions and improve the 
propulsive efficiency, Bowker and Townsend (2022). As 
energy-saving devices of a ship, bow foils are commonly 
made using metallic materials, which have low resistance 
towards salinity. Hence, there is a rising trend to use 
polymer composites instead of metallic materials in 
submarine device manufacturing, Natarajan et al. (2023). 
This paper focuses on the structural testing of two bow 
foil demonstrators which were manufactured using glass 
fibre-reinforced polymer composites. The two 
demonstrators, sharing the same geometry, represent the 
core component of a bow foil, which mainly resists 
bending force. The 1.0 m long demonstrators consist of 
two caps and one web, forming an I-shaped cross-section. 
One demonstrator was assembled using both adhesive and co-cured joints, while the other one contained two 
co-cured joints. Four-point bending tests (Figure 1) were performed as the bow foil was expected to suffer high 
bending. Strain gauges and displacement sensors were employed to monitor the demonstrators’ structural 
performance during testing. Test results revealed that both demonstrators shared a similar failure mechanism, 
namely local shear failure around the loading region. The co-cured demonstrator failed under a load of 123 
kN, which is almost the same as that of the glued demonstrator. In terms of weight, the co-cured demonstrator 
is approximately 4% lighter than the other one. However, the co-cured demonstrator had approximately 9% 
more mid-span deflection under the same load. Both demonstrators showed failure loads greater than the scaled 
foil load, proving that it is promising to use glass fibre/epoxy resin composites to manufacture bow foils. The 
development of bow foils will result in a reduction in ship fuel consumption of up to 20%, reducing carbon 
emissions for achieving climate neutrality by 2050. 
References 
J.A. Bowker and N.C. Townsend. A probabilistic method to evaluate bow foils for realistic seas and shipping 
routes. Applied Ocean Research, 129:103374, 2022. doi: 10.1016/j.apor.2022.103374. URL: 
https://www.sciencedirect.com/science/article/pii/S0141118722003054. 
E. Natarajan, L.I. Freitas, M.S. Santhosh, K. Markandan, A.A.M. Al-Talib, C.S. Hassan. Experimental and 
numerical analysis on suitability of S-Glass-Carbon fiber reinforced polymer composites for submarine hull. 
Defence Technology, 19:1-11, 2023. doi: 10.1016/j.dt.2022.06.003. URL: 
https://www.sciencedirect.com/science/article/pii/S2214914722001313 
Figure 1: Four-point bending testing of the 
demonstrator. 


Experimental testing of glass fibre/epoxy resin composite bow foil demonstrators for ships

Broglia*, R.

Posa, A.

Viola, I.

 
 
XI International Conference on Computational Methods in Marine Engineering 
 
 
Effects of nacelle and tower on the wake recovery of a hydrokinetic turbine 
 
Riccardo Broglia1*, Antonio Posa1, and Ignazio Maria Viola2 
 
1 Institute of Marine Engineering, National Research Council of Italy, Via di Vallerano 139, 00128 
Roma, Italy 
2 School of Engineering, Institute for Energy Systems, University of Edinburgh, Edinburgh, EH9 
3FD, UK 
 
* riccardo.broglia@cnr.it 
 
ABSTRACT 
Detached eddy simulation is adopted to investigate the wake development downstream of an axial-flow 
turbine. Both the isolated rotor and the complete configuration (i.e., including nacelle and tower) are 
analysed in depth for a range of tip speed ratios. For the isolated rotor we found (see Posa et al., 2024) that 
the trend of the momentum deficit as a function of the rotational speed changes between the near wake and 
further downstream. While the momentum deficit in the near wake is a growing function of the rotational 
speed, it becomes a decreasing function further downstream. This behaviour is due to the acceleration of the 
instability of the tip vortices, triggering the process of wake recovery through both radial advection and 
turbulent mixing (Lignarolo et al. 2014, 2015 and Posa & Broglia, 2021). In the present study, the 
computations including tower and nacelle demonstrate that they strongly influence the wake dynamics, with 
a clear anticipation of the mutual inductance between tip vortices, their pairing and eventual break-up into 
turbulence. As a result, wake recovery occurs more upstream when the presence of the nacelle and 
supporting tower is included in the computational model. The results of the present computations 
demonstrate indeed that mutual inductance phenomena between tip vortices develop at shorter downstream 
distances. This result has important implications, since axial-flow turbines are usually deployed in array 
configurations, where the downstream devices ingest the wake coming from the upstream ones. The flow 
structures they shed, especially the tip and hub vortices, are sources of fatigue loads on the downstream 
turbines, while the speed of the wake recovery affects the momentum actually available to them. Therefore, 
faster instability of the wake structures and wake recovery enable closer streamwise distances between 
devices. The results of this study highlight the importance of taking into account the effects of both the 
typical tip speed ratios of operation and the supporting structures of the rotor for an accurate assessment of 
the speed of their wake recovery and the optimal distance between turbines in farms of multiple devices. 
This work received funds from the UK Engineering and Physical Sciences Research Council (EPSRC) 
(Grant No. EP/V009443/1). 
References 
Posa, A., Viola. I.M. and Broglia, R., 2024. Influence of the tip speed ratio on the wake dynamics and 
recovery of axial-flow turbines, Physics of Fluids 36, p.055109. 
Lignarolo, L.E.M., Ragni, D., Krishnaswami, C., Chen, Q., Ferreira, C.S. and Van Bussel, G.J.W., 2014. 
Experimental analysis of the wake of a horizontal-axis wind-turbine model. Renewable Energy, 70, pp.31-46. 
Lignarolo, L.E.M., Ragni, D., Scarano, F., Ferreira, C.S. and Van Bussel, G.J.W., 2015. Tip-vortex instability 
and turbulent mixing in wind-turbine wakes. Journal of Fluid Mechanics, 781, pp.467-493. 
Posa, A. and Broglia, R., 2021. Momentum recovery downstream of an axial-flow hydrokinetic turbine. 
Renewable Energy, 170, pp.1275-1291. 


Effects of nacelle and tower on the wake recovery of a hydrokinetic turbine

Maki, K.

Geremia*, P.

Paolo, B.

 
 
XI International Conference on Computational Methods in Marine Engineering 
 
 
A Data-Driven Method for Performance Evaluation 
 of Wind-Assisted Ship Propulsion  
 
Kevin J. Maki1,*, Paolo Geremia2 and Benedetto di Paolo2 
 
1 Department of Naval Architecture and Marine Engineering, 
University of Michigan, Ann Arbor, MI, USA. 
 
2 Engys SRL 
Strada per Vienna, 9, 34151 Trieste, Italy 
 
* kjmaki@umich.edu 
 
ABSTRACT 
Wind assisted ship propulsion (WASP) is an attractive way to practically reduce fuel consumption for 
commercial ships.  For example the paper by Lu and Ringsberg (2020) compares three different WASP 
technologies for use on a real ship on its transatlantic route, and they estimate net fuel savings of 5-9%. Another 
example of WASP technology is the paper by Viola et. al (2015) that shows how a high-performance wing sail 
on a crude carrier can provide more than 10% of the total propulsive force. The activity on WASP has flourished 
to the point where the ITTC has a new specialist committee to track and recommend best practices to support 
the adoption of this promising technology. 
The number of concepts to harness propulsion from the wind are many, and each must be evaluated in a full 
range of wind and sea conditions. Computational fluid dynamics can help evaluate different ship and WASP 
designs, but the complex aerodynamic and hydrodynamic interaction requires dense grids with small time-
steps, and the computational costs of using overset meshes or sliding grids prohibit CFD from being widely 
used. 
In this paper the author team will present a data-driven method (based on the work of Knight and Maki 2024) 
to efficiently assess the performance of a WASP vessel. The method trains the data-driven model by performing 
simulations of the WASP technology for a range of wind conditions, and then the model is applied to the 
equations of motion for simulation of the vessel in calm-water and waves.  The method is shown to 
significantly reduced the computational expense and to be effective to evaluate many different types of WASP 
technologies in a full range of wind and ocean conditions. 
References 
Bradford G. Knight and Kevin J. Maki. “Fast-running CFD calculations of the ONR Tumblehome performing 
maneuvers in calm water and in waves using a Gaussian process regression propeller and rudder model.” 
Ocean Engineering, 2024, vol. 303, 117671. 
Ruihua Lu and Jonas W. Ringsberg. “Ship energy performance study of three wind-assisted ship propulsion 
technologies including a parametric study of the Flettner rotor technology.” Ships and Offshore Structures.  
2020, vol. 15, no. 3, pp 249-258. 
I.M. Viola, M. Sacher, J. Xu, and F. Wang. “A Numerical Method for the Design of Ships with Wind-Assisted 
Propulsion.” Ocean Engineering, 2015, vol. 105, pp 33-42. 
 


A Data-Driven Method for Performance Evaluation of Wind-Assisted Ship Propulsion

Zhang, Y.

Hosseinzadeh, S.

Sin, D.

Kurt, M.

Banks*, J.

Hudson, D.

XI International Conference on Computational Methods in Marine Engineering
Investigation of Leeway Angle on Wake Fraction for a Twin-Screw
Wind-Assisted Ship Using CFD and PIV Measurements
Yifu Zhang1,2,∗, Saeed Hosseinzadeh1, Dixon Sin1, Melike Kurt1, Joseph Banks1, Dominic Hudson1,
Martyn Prince3, Stephen Turnock1
1 Maritime Engineering Research Group, School of Engineering, University of Southampton, UK
2 High Performance Computing (HPC) Team, iSolutions, University of Southampton, UK
3 Wolfson Unit MTIA, University of Southampton, UK
∗ Yifu.Zhang@soton.ac.uk
ABSTRACT
The integration of wind-assisted propulsion systems in modern ships offers a promising pathway to reduce fuel
consumption and greenhouse gas emissions. For these vessels, understanding the wake fraction—the propor-
tion of the ship’s speed lost due to the surrounding flow field—is critical for accurately predicting propulsion
performance. The leeway angle, induced by side forces from wind-assisted devices, further complicates the
wake dynamics, potentially altering the nominal and effective wake at the propeller. This study explores the
influence of leeway angle on the wake fraction of a 3 meter model scale twin-screw bulk carrier, providing
essential insights for optimizing wind-assisted ship designs.
Numerical simulations are conducted to model the flow field around the hull, rudders and propellers, with and
without a leeway angle applied, using a RANS-based solver. Both nominal and effective wake fractions are
analysed, capturing the detailed wake structures at and behind the propeller plane. The CFD simulations in-
corporate realistic hull geometries and operational parameters, enabling accurate representation of the wake
dynamics. These numerical predictions form a critical part of the investigation, serving as a baseline for vali-
dating experimental findings.
Model tests complement the numerical work through Underwater Particle Image Velocimetry (UPIV) mea-
surements performed at and behind the propeller plane of the twin-screw bulk carrier. The experiments are
conducted in a Boldrewood Towing Tank facility under controlled conditions, with and without the application
of leeway angle. The UPIV setup uses stereo imaging, capturing the three-dimensional velocity fields across
the measurement plane in the wake, providing high-resolution data to calculate both nominal and effective wake
fractions. These measurements offer a direct comparison to the numerical predictions, enabling the impact of
various numerical modelling parameters on the CFD accuracy to be assessed and further understanding of wake
modification caused by leeway.
This combined approach aims to deepen our understanding of how leeway and rudder angles impact wake
fractions, providing critical insights to support the design and optimization of wind-assisted propulsion systems.


Investigation of Leeway Angle on Wake Fraction for a Twin-Screw Wind-Assisted Ship Using CFD and PIV Measurements

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