Scipedia

Lopes*, R.

Eslamdoost, A.

Bensow, R.

Ponkratov, D.

XI International Conference on Computational Methods in Marine Engineering
Blind Resistance Prediction Using CFD - A Summary of the Lucy Ashton
Workshop
Rui Lopes1,∗, Arash Eslamdoost1, Rickard E. Bensow1 and Dmitriy Ponkratov2
1 Department of Mechanics and Maritime Sciences
Chalmers University of Technology, Gothenburg, Sweden
2 Siemens Digital Industries Software
London, UK
∗ rui.lopes@chalmers.se
ABSTRACT
The confidence in using CFD for full-scale predictions is hampered by the lack of validation at full-scale, where
measurements are much scarcer than at model-scale. In particular when it comes to ship resistance, it would
appear to be extremely difficult to perform bare hull experiments at full-scale in a similar manner as they are
conducted at model-scale. However, some cases exist that prove this to be possible, such as the towing of
the H.M.S. Greyhound (Froude, 1874) and the ”Lucy Ashton” measurement campaign in the 1950s (Conn et
al., 1953; Denny, 1951; Lackenby, 1954; Smith, 1955). In the latter, the ”Lucy Ashton” paddle steamer was
fitted with four jet engines on its deck for propulsion, thus avoiding the need for a propeller and consequently
propeller-hull interaction effects. As a result, the ”Lucy Ashton” experiments provide a rare and valuable
opportunity. Despite its merits, this campaign is not well known in the maritime community.
As part of the JoRes project, a blind CFD workshop based on the ”Lucy Ashton” trials was organised and took
place in 2024. This contribution provides an overview of the workshop, which received data from more than
40 different participants. Results for varying model-sizes at a constant Froude number, and variable Froude
number at full-scale were received. Discrepancies in the reported resistance between participants were larger
at model-scale rather than at full-scale, as a consequence of different approaches to handle the boundary-layer,
i.e. wall-resolved vs wall-functions. The numerical results tended to underpredict the measured values since
roughness was not considered and the simulations were carried out at even keel.
References
J. F. C. Conn, H. Lackenby and W. P. Walker. B.S.R.A. Resistance experiments on the ”Lucy Ashton”. Part II -
The ship-model correlation for the Naked Hull Conditions, Proceedings of the Spring Meeting of the Institution
of Naval Architects, London, United Kingdom, 1953.
M. E. Denny. B.S.R.A. Resistance experiments on the ”Lucy Ashton”. Part I - Full-Scale Measurements, Pro-
ceedings of the International Conference of Naval Architects and Marine Engineers, London, United Kingdom,
1951.
W. Froude. On Experiments with H.M.S. ”Greyhound”, Transactions of the Royal Institution of Naval Archi-
tects, Volume 15, 1874.
H. Lackenby. B.S.R.A. Resistance experiments on the ”Lucy Ashton”. Part III - The ship-model correlation
for the shaft-appendage conditions, Proceedings of the Autumn Meeting of the Institution of Naval Architects,
Torquay, United Kingdom, 1954
S. L. Smith. B.S.R.A. Resistance experiments on the ”Lucy Ashton”. Part IV - Miscellaneous Investigations
and general Appraisal, Proceedings of the Spring Meeting of the Institution of Naval Architects, London, United
Kingdom, 1955


Blind Resistance Prediction Using CFD - A Summary of the Lucy Ashton Workshop

Wang*, C.

Nader, M.

Stambaugh, K.

Leibman, L.

 
 
XI International Conference on Computational Methods in Marine Engineering 
 
 
6-DOF Simulation of High-Speed Boat Maneuvering 
 
Chengjie Wang,1*, Michael M. Nader,2 Karl Stambaugh,3 and Larry Leibman4 
 
1 Simerics, Inc, 
1750 112th Ave NE. Ste C250, Bellevue, WA 98004, USA. 
 
2 US Coast Guard SFLC, ESD 
 
3 US Coast Guard SFLC, ESD (ret) 
 
4 Orca3D, LLC 
Annapolis, MD 21403, USA. 
 
* Chengjie.Wang@simerics.com. 
 
ABSTRACT 
Designing high-speed boat rudders and appendages is most often based on empirical relationships of 
appendage and underbody lateral projected area.  The empirical approach does not reflect objective evaluation 
of desired characteristics nor performance in a seaway.  This effort was initiated to determine if higher fidelity 
simulations will provide insights into rudder and appendage sizing in calm water maneuvers and eventually in 
a seaway. Six Degree-of-Freedom (6-DOF) free-running simulations of high-speed boats conducting standard 
ship maneuvers are performed using a RANS-based computational fluid dynamics (CFD) tool as described in 
Wang, Snodgrass, and Ding (2019). The explicit Volume of Fluid (VOF) method is employed to accurately 
capture the complex free surface dynamics, ensuring precise representation of the interaction between the hull 
and the water. To accurately model the dynamic propulsive forces during the maneuvers, actual propeller 
geometries are incorporated into the simulations.  
The simulation results are validated against experimental data for the USCG 47ft Motor Lifeboat (47 MLB). 
Multiple maneuvering sea trials were conducted for the 47 MLB under various conditions, including different 
speeds and appendage configurations. Full scale data used in the included standard tactical diameter and zig-
zag maneuvers.  By comparing the simulated and experimental results, the accuracy and reliability of the CFD 
tool are assessed. Key performance metrics, such as resistance, heave/pitch, and maneuvering characteristics, 
like minimum turning radius, are compared to validate the simulation's predictive capabilities. Furthermore, 
an improved propeller force model is proposed to enhance the ability to predict propulsive forces during boat 
maneuvering, especially in dynamic conditions where propeller unsteady flow effects can significantly 
influence performance. It is anticipated that this force model could be applied during new vessel design when 
the details of the propeller three-dimensional geometry are not yet available, or it is not computationally 
feasible to analyse the actual propeller geometry. 
The comparisons of simulations and measured data provides valuable insights into rudder and appendage 
design.  
References 
C. Wang, J. Snodgrass, and H. Ding. The Simulation of Ship Maneuvering Using a RANS-Based CFD Tool. 
Paper presented at the SNAME Maritime Convention, Tacoma, Washington, USA, October 2019. 


6-DOF Simulation of High-Speed Boat Maneuvering

Heilshorn*, E.

Knight, B.

Silva, K.

Maki, K.

XI International Conference on Computational Methods in Marine Engineering
Propeller and Rudder Interaction in Large-Amplitude Waves 
Eric Heilshorn1,*, Bradford G. Knight2, Kevin M. Silva3 and Kevin J. Maki1 
1 Department of Naval Architecture and Marine Engineering,  
University of Michigan, Ann Arbor, MI USA. 
2 Department of Ocean Engineering, University of Rhode Island, Kingston, RI, USA. 
3 Naval Surface Warfare Center Carderock Division, West Bethesda, MD, USA. 
* ejheilsh@umich.edu. 
ABSTRACT 
The control of ships in large amplitude seaways depends on the interaction of the ship 
propulsion and rudders to keep the ship on the desired course. The rudder and 
propeller must be designed to control the ship in conditions that pose risk of capsize. 
Also, the rudder and other appendages must be sized to comply with other 
maneuvering in waves criteria. Computational Fluid Dynamics (CFD) has made little 
impact towards assessment of maneuvering in waves because the number of 
conditions that must be considered are too numerous to afford CFD.  This is primarily 
due to the cost of discretizing the rudder and propeller with sliding or overset meshes. 
Recent work by the author team has developed a 
rudder propeller modeling framework that 
alleviates the need to discretize the control surfaces 
when per forming s imula t ions fo r sh ips 
maneuvering in waves (Knight and Maki 2024). 
The existing rudder propeller model is trained with 
double-body CFD computations of the propellers 
and rudders operating in the behind condition in 
different conditions, and the effect of waves is 
imposed with linear superposition. The current paper will describe work that extends 
the rudder and propeller model to include training in conditions that have large-
amplitude waves, and to explicitly account for the wave-hull-propeller-rudder 
interaction.  A set of focused waves from sea-state seven will be used to study the 
interaction between the waves and the rudder and propeller forces (see Figure 1).
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.
Figure 1: Ensemble of Focused Waves


Propeller and Rudder Interaction in Large-Amplitude Waves

Mourlas*, C.

Papatheocharis, T.

Gavriilidis, I.

Karamanos, S.

 
 
XI International Conference on Computational Methods in Marine Engineering 
 
 
 
High-Frequency Mechanical Impact Effect on High-Cycle Fatigue of Welded 
Steel Connections for Offshore Structures 
 
Christos K. Mourlas1,*, Theocharis Papatheocharis1, Ilias Gavriilidis1 and Spyros A. Karamanos1 
 
1Department of Mechanical Engineering, University of Thessaly 
Pedion Areos, 38334 Volos, Greece. 
 
 
* mourlaschristos@gmail.com 
 
 
 
 
ABSTRACT 
The present paper presents the fatigue performance of twelve (12) full-penetration welded T-joint specimens 
commonly used in offshore tubular steel structures. The research work is part of an extensive Greek national 
research program with the acronym SIRENES, focusing on the structural integrity of offshore structures for 
renewable energy production. It is the continuation of the European REFOS project for developing hybrid 
tension-leg-platforms (TLP) installed in deep water locations for combined wind and wave energy production. 
The study focuses on the effect of High-Frequency Mechanical Impact (HFMI) post-weld treatment on welded 
joints fatigue life. The full-penetration welds represent the brace-to-chord connections of the offshore structure. 
The specimens are made of either mild steel S355 or high-strength steel S700, and are subjected to four-point 
bending cyclic loading under a constant load amplitude with a load ratio (R=0.5). Two welding techniques for 
the connection have been employed: (a) manual (semi-automatic) weld; (b) manual weld with HFMI post-
weld treatment. Crack initiation and propagation along the weld toe is monitored during testing using magnetic 
particle inspection. A three-dimensional numerical model of the welded connections is also developed using 
ABAQUS/Standard FE software to support the experiments accounting for material properties based on 
uniaxial tests of coupon specimens extracted from the same steel sheet used for specimens fabrication. 
 
References 
T. Papatheocharis, G. T. Plakias, A. D. Zervaki, P. C. Perdikaris, S. A. Karamanos. Ultimate Strength and 
Fatigue of Stiffened Welded Tubular Joints in Floating Energy Production Structures. Engineering Structures, 
297:116985, 2023. doi: 10.1016/j.engstruct.2023.116985. https://doi.org/10.1016/j.engstruct.2023.116985 
Mavrakos, S.A. et al.. Life-Cycle Assessment of a Renewable Energy Multi-Purpose Floating Offshore System: 
Final report of REFOS project. Brussels, European Commission, 2020. 
 
 


High-Frequency Mechanical Impact Effect on High-Cycle Fatigue of Welded Steel Connections for Offshore Structures

Dai, S.

Wang, Y.

Zhou, X.

Liu, Y.

Zhang*, X.

 
 
XI International Conference on Computational Methods in Marine Engineering 
 
 
Physical-data driven hybrid modelling for structural optimization of buckling 
resistance of wind turbine blades bio-inspired by beetle elytron 
 
First A. Shenglin Dai1, Second B. Yuhang Wang1, Third C. Xuhong Zhou1, Fourth D. Yingyi Liu2 
and Fifth E. Xiaoming Zhang1,* 
 
1 School of Civil Engineering, Chongqing University, Chongqing, 400045, China. 
 
2 Research Institute for Applied Mechanics, Kyushu University, Fukuoka, 8168580, Japan. 
 
* Corresponding Author: xiaomingzhang@cqu.edu.cn. 
 
ABSTRACT 
Wind turbine blades, designed as sandwich structures, 
are susceptible to compressive buckling [1,2], due to 
Brazier effect caused by the curvature that arises from 
flap-wise bending deformations [3,4]. This study, 
therefore, introduces a beetle elytron-bioinspired 
trabecular core, featuring thin-walled cylindrical 
trabeculae with lateral supports and end’s chamfers, 
providing superior compressive performance over 
conventional web cores [5]. However, there has been a 
lack of study on optimizing the parameters in terms of 
compressive strength (σu) of trabecular cores. Three 
trabecular-related dimensionless parameters are 
introduced: the ratio of trabecular radius to cellular 
length (η), chamfer radius to trabecular radius (ξt) and 
core height to core thickness (β), which have been 
incorporated into 32 sets of coupon test, revealing that local buckling is the preferred mode. Due to the complex 
relationships between these parameters, a physical-data driven hybrid modelling is used to establish 
optimization functions. The physical condition, preference for local buckling in trabecular cores, guides the 
derivation of the buckling mode critical function ϕ(x), which is adapted from that of comparable cylindrical 
shells; and the boundary constraint coefficient (x) of trabecular cores is then determined using a data-driven 
predictive model trained on test results. The optimization results are validated through experimental data and 
numerical models, which are employed to identify the optimal combination of trabecular-related parameters 
with various radius-to-thickness ratio (D) for the sectional design of trabecular cores in wind turbine blades.  
References 
[1] J. Tang, X. Chen, Experimental investigation on ultimate strength and failure response of composite box 
beams used in wind turbine blades, Compos. Struct. 198 (2018) 19-34.  
[2] X. Chen, W. Zhao, X.L. Zhao, J.Z. Xu, Failure test and finite element simulation of a large wind turbine 
composite blade under static loading, Energies 7(4) (2014) 2274-2297. 
[3] F.M. Jensen, B.G. Falzon, J. Ankersen, H. Stang, Structural testing and numerical simulation of a 34 m 
composite wind turbine blade, Compos. Struct. 76(1-2) (2006) 52-61. 
[4] F.M. Jensen, P.M. Weaver, L.S. Cecchini, H. Stang, R.F. Nielsen, The Brazier effect in wind turbine blades 
and its influence on design, Wind Energy 15(2) (2012) 319-333. 
[5]  J. Chen, X. Zhang, Y. Okabe, K. Saito, Z. Guo, L. Pan, The deformation mode and strengthening 
mechanism of compression in the beetle elytron plate, Mater. Design 131 (2017) 481-486. 
Figure 1: Wind turbine blade and its mechanical 
analysis model under Brazier effect. 


Physical-data driven hybrid modelling for structural optimization of buckling resistance of wind turbine blades bio-inspired by beetle elytron

Levine*, M.

Edwards, S.

 
 
XI International Conference on Computational Methods in Marine Engineering 
 
Machine Learning for Ocean Wave Height Estimation 
 
Michael D. Levine1 and Samuel J. Edwards1* 
 
1 Naval Surface Warfare Center – Carderock Division 
9500 MacArthur Blvd, Bethesda, MD 20817, USA 
 
* Corresponding Author: samuel.j.edwards33.civ@us.navy.mil 
 
ABSTRACT 
 
Safe operation of a ship requires accounting for ship motion responses in stochastic ocean waves.  Excessive 
ship motions can lead to hazardous and unsafe conditions such as pure loss of stability, surf-ride and broaching 
(IMO, 2020).  Mitigation of these risks can be performed through selection of ship speeds and headings for a 
given seaway, and avoiding conditions likely to lead to severe motions.  Estimation of wave conditions is 
typically based on weather forecast data.  However, significant variability can exist between predicted wave 
conditions from a general area forecast, and the actual conditions in the local vicinity of the vessel.  
Additionally, the fidelity of a given weather forecast degrades as a function of time.  Alternatively, local 
conditions can be measured off-board by wave buoys, but this requires deployment and retrieval of sensor 
hardware as well a transmission and processing of buoy data.  By effectively employing the “ship as buoy”, 
on-board measurements of ship motion responses to a seaway can potentially help address estimation of local 
wave conditions (Nielsen et al., 2023). 
 
A new data-adaptive model is investigated as a prospective capability for estimation of ocean wave height 
based on ship motions.  Long Short-Term Memory (LSTM) neural networks are trained and tested with 
physics-based Large Amplitude Motion Program (LAMP) simulation data.  This approach focuses on 
prediction of wave height based on simulated 6-DOF ship motion responses.  LSTM networks are trained and 
tested with simulated wave time-series data as the target and motion time-series as inputs.  For training data, 
wave-series are generated based on the Longuet-Higgins model.  LAMP simulations and LSTM training are 
performed over a set of irregular unidirectional wave conditions in Sea States 5 and 6.  From initial results, 
this machine learning approach has the potential to produce results consistent with a physics-based model.   
References 
IMO “Interim Guidelines on the Second Generation Intact Stability Criteria”, MCS.1/Circ. 1627, International 
Maritime Organization, London, UK`, 2020.I. M. Viola and R. G. J. Flay. Pressure Distribution on Sails 
Investigated using Three Methods: On-Water Measurements, Wind-Tunnel Measurements, and Computational 
Fluid Dynamics. In 20th Chesapeake Sailing Yacht Symposium, 2011. 
U.D Nielsen., H.B. Bingham., Brodtkorb, A. H., Iseki, T., Jensen, J. J., Mittendorf, M., Mounet, R. E. G., Shao, 
Y., Storhaug, G., Sørensen, A. J., and Takami, T., (2023). Estimating Waves via Measured Ship Responses. 
Scientific Reports, Vol. 13 
 


Machine Learning for Ocean Wave Height Estimation

Sato*, Y.

Takeda, S.

Matsuura, K.

Okada, Y.

Matsuka, T.

Hamada, S.

A Basic Study on Estimating the Effects of Wind Propulsion Systems

Schot*, J.

Garenaux, M.

 
 
XI International Conference on Computational Methods in Marine Engineering 
 
 
Efficient prediction of aerodynamic interaction effects including optimised 
controls for wind propulsion 
 
J. J. A. Schot1,*, M. Garenaux1, 
 
1 Maritime Research Institute Netherlands (MARIN) 
Haagsteeg 2, 6708 PM, Wageningen, The Netherlands 
 
* j.j.a.schot@marin.nl. 
 
ABSTRACT 
The power savings obtained from a configuration of wind propulsors on a vessel is affected by the location of 
the wind propulsor in the atmospheric boundary layer, the interaction of the wind propulsor with the ship and 
superstructure and the interaction between the wind propulsors. In additions the controls of the wind propulsors 
should be adapted to these interactions. Inclusion of these interaction effects is required for the EEDI (IMO, 
2020) and all but the lowest fidelity performance predictions (ITTC, 2024). Some guidance is available on 
generating data for a specific condition (ITTC, 2024), but no methodology is specified to generalise data to all 
the wind and operational conditions covered in a performance prediction. Such a methodology is especially 
relevant when using numerical methods instead of wind tunnel tests.  
MARIN developed the “effective wind model” for this purpose (Garenaux and Schot, 2021), using a 
combination of the standalone performance of the wind propulsor, CFD for the interaction between the wind 
propulsor and ship and superstructure and a non-linear lifting line method (Schot and Garenaux, 2023) for the 
interaction between the wind propulsors. The “effective wind model” is described together with the integration 
of the aerodynamic interaction effects in a performance prediction. Finally, the predicted aerodynamic 
performance is validated using CFD for a configuration or rotor sails and rigid wing sails on a bulk carrier as 
shown in Figure 1.  
 
 
 
Figure 1: Results from the validation using CFD for a configuration of rigid wing sails. 
References 
IMO. MEPC.364(79): 2022 Guidelines on the method of calculation of the attained energy efficiency design 
index for new ships (2022) 
ITTC. 7.5-0.2-03-01.9: Recommended Procedures and Guidelines - Predicting the Power Saving of Wind 
Powered Ships (2024) 
M. Garenaux, J. J. A. Schot. Flettner rotors performance and interaction effects on the MARIN Hybrid 
Transition Coaster. International conference on Wind Propulsion, 2021. 
J. J. A. Schot, M. Garenaux. Modelling of aerodynamic interaction effects for wind propulsion applied in 
commercial shipping: Development of a non-linear lifting line method. INNOV’SAIL, 2023. 


Efficient Prediction of Aerodynamic Interaction Effects Including Optimised Controls for Wind Propulsion

Marri*, S.

Kacimi, A.

Moçayd, N.

Seaid, M.

XI International Conference on Computational Methods in Marine Engineering
Bernstein-Bézier finite elements with perfectly
matched layer for the prediction of wave agitation in harbors and coastal regions
S. El Marri1∗, A. El Kacimi1, N. El Moçayd2, and M. Seaid3
1 Laboratory of Modeling and Combinatorial, FP Safi, Cadi Ayyad University, Morocco
2 College of Agriculture and Environmental Sciences, Mohammed VI Polytechnic University,
Benguerir, Morocco
3 Department of Engineering, Durham University, Durham DH1 3LE, UK
∗ Email: saloua.elmarri@ced.uca.ma
ABSTRACT
The aim of this work is to effectively solve wave prob-
lems, governed by the linear elliptic mild-slope equa-
tion (MSE), on unstructured triangular mesh grids
based on the Bernstein-Bézier finite elements. The
present model enables to account for non-uniform
bathymetry and to accurately describe wave agitation
problems. A domain truncation method relying on
the perfectly matched layer (PML) concept is per-
formed to address the issues related to open region
domains [1]. The proposed PML model uses a non-
standard weak form of the truncated MSE to handle
the incident wave field weakly and takes into account
external bathymetry effects [2]. A low-complexity
procedure, exploiting the tensorial property of Bern-
stein polynomials in conjunction with the sum fac-
torisation method, is applied to set up the local high-
order FE matrices. Additionally, static condensation
is applied element-wise to reduce the memory re-
quirements. The computer model is extended to pre-
dict the wave field in a harbor of arbitrary shape and
bathymetry, where the effects of wave reflection, re-
fraction, diffraction, dissipation losses, due to (par-
tially) reflecting boundaries are incorporated. A case
study of Mohammedia port is considered to demon-
strate the performance of our numerical model.
REFERENCES
[1] J. BÉRENGER, A perfectly matched layer for the absorption of electromagnetic waves. Journal of Com-
putational Physics, 114:185–200, 1994.
[2] PANCHANG, V., W. CHEN, B. XU, K. SCHLENKER, Z. DEMIRBILEK, AND M. OKIHIRO (2000),
Exterior bathymetric effects in elliptic harbor wave models. J. Waterw. Port Coast. Ocean Eng. 126 (2),
71–78.


Bernstein-Bézier Finite Elements With Perfectly Matched Layer for the Prediction of Wave Agitation in Harbors and Coastal Regions

Peiró Alemany, Josep Maria

Furro-Estany, Eduard

Bugeda, Jaume

Sicilia, Oscar

Montero-Homs, Jaume

LA RECONFIGURACIÓ DEL TRANSPORT EN LA TRANSICIÓ ENERGÈTICA - 4t. CONGRÉS D’ECONOMIA I EMPRESA DE CATALUNYA

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