1 Introduction

The ship is an ancient object; the seafaring culture has a millenary tradition. Sea has always been the main way of communication between peoples, goods and a way of exchanging culture above all. The sea is the primary source of food, offers a great potential as renewable energy resources and still more than 80% of goods travel by sea.

The activities of the naval architect and of the marine engineer are focused at the design, construction and operation of ships and offshore structures involved in the activities carried out in the marine environment for the use of natural resources. These complex artefacts require multiple skills in fields such as hydrodynamics, fluid dynamics, theory of structures, fluid machines, automation and automatic controls, as well as expertise in management and economics.

Therefore, the inclusion of Naval Architecture and Marine Engineering (NAME) researchers in a broader context such as the Department of Industrial Engineering appears natural with the vision of the fruitful exchange of skills and results and successful collaborations among researchers from all fields embodied in the new Department. In recent years the growing attention of civil society and consequently of political authorities to environmental issues has led to a close collaboration between NAME researchers and those of the chemical, fluid machine mechanical and aerospace areas, related to the energy production from marine renewable sources (offshore wind, production of energy from marine currents and waves, etc.) and to the zero emissions demand in marine transportation (fuel cell, hydrogen propulsion, etc.). Another exquisitely multidisciplinary field is that of autonomous vehicles, where ships cannot be missing, in which cooperation between skills and a transversal approach is crucial.

The skills in the NAME field can be divided, for simplicity of description and for their historical development, into three major cultural areas: Naval Architecture, Naval Construction, and Marine Plants. The topics of interest of Naval Architecture are the conception and design of different ships and marine structures including special, military, submarine, and pleasure units, optimization of the hull form with particular regard to the resistance and the hydrodynamic aspects of the propulsion (unconventional propellers or thrusters), to reduce fuel consumption and emissions, and improve the seaworthiness, i.e., the behaviour of the vessel at sea, manoeuvrability and steering, operational safety and stability against the risk of capsizing or sinking in the event of damage. For these purposes, the numerical and experimental methodologies are developed and used in all phases of design. The topics of interest of Naval Constructions are, in the context of structural aspects, the actions applied to the structures, materials, technological and production processes, the analysis of the static and dynamic structural response, the dimensioning, outfit and fitting. The topics of interest in the Marine Plants area are the propulsion and energy generation plants, the systems for onboard services, the sensors and safety equipment, and the automatic control systems.

In order to increase safety, energy efficiency and comfort and to reduce consumption, and emissions in the atmosphere and in the sea, the life cycle assessment is considered in complete process: design, operation, maintenance, decommissioning. The studies of the sector, addressed with theoretical, numerical and experimental approaches and with deterministic and probabilistic models, are aimed at sustainable mobility and the growth of the sea economy, with recourse to traditional and innovative solutions.

2 Background and Legacy

In the context of the Neapolitan university, the course of Naval Architecture and Marine Engineering is among the oldest, given the consolidated tradition in shipbuilding in the area.

The systematic arrangement of engineering studies dates back to 1808 when Gioacchino Murat established the “Corpo Reale degli Ingegneri di Ponti e Strade” (Royal Corps of Bridges and Roads Engineers) with the consequent establishment of the “Scuola di Applicazione de’ Ponti e Strade” (School of Application of Bridges and Roads, 1811). After several vicissitudes, in 1863 the School passed under the control of the Ministry of Public Education and became the “Scuola di Applicazione per gli Ingegneri” (Application School for Engineers). In 1901 a new Industrial Engineering section was introduced and in 1904 the School of Application was transformed into the Polytechnic School. In 1905, at the Polytechnic School, the naval section was established, with the right to award degrees in “Ingegneria Navale e Meccanica” (Naval Architecture and Mechanical Engineering). The Institutes of “Architettura Navale” (Naval Architecture) and “Costruzioni Navali” (Shipbuilding) are born, to which the Institute of “Macchine Marine” (Marine Machinery) was added.

It is necessary to mention the work of Prof. Mario Gleijeses, director of the Institute of “Architettura Navale” from 1907 to 1950, and of prof. Leonardo Fea, director of the Institute of “Costruzioni Navali” from 1926 to 1954.

The marine section has therefore been characterized since its inception in the university environment by a strong bond with the industrial tradition and, in particular, with mechanics.

In 1925 the Polytechnic School changed its name to become the “Reale Scuola di Ingegneria di Napoli” (Royal Engineering School of Naples). In 1935 the Faculty of Engineering was born.

In 1965 the new headquarters of the Faculty of Engineering was inaugurated in Piazzale Tecchio. The Vasca Navale, (Towing Tank), an important laboratory of marine hydrodynamics, dedicated to the experimentation on ship models, was built within the laboratories of the Faculty. The towing tank is still among the largest in Europe for dimensions in the university area (Fig. 1).

In 1984 the “Dipartimento di Ingegneria Navale (DIN)” (Department of Naval Architecture and Marine Engineering) was established, merging the Institutes of “Architettura Navale”, “Costruzioni Navali” and “Macchine Marine”. The professors and researchers of these Institutes become part of this structure.

The DIN promoted and coordinated research activities in the sectors of marine hydrodynamics, naval installations, naval structures, marine technologies and ship safety; contributes to the activities of the Degree Course in Naval Architecture and Marine Engineering and the PhD in Aerospace, Naval and Quality Engineering.

In addition to the hydrodynamics laboratory mentioned above, the Department of Naval Architecture and Marine Engineering has: a plant laboratory capable of carrying out experimental investigations even at sea; a computing center for processing experimental data and developing numerical surveys with modern automatic calculation procedures; a mechanical workshop and foundry, a carpentry shop, an electrical-electronic workshop, a system for surface and underwater photographic and television shooting; a library specializing in naval architecture and marine engineering disciplines.

It was a member of the International Associations: ITTC, International Towing Tank Conference; ISSC, International Ship Structure Conference; SRDC, Stability Research and Development Centre; WEGEMT, West European Graduate Education in Marine Technology (actually CEMT, Confederation European Maritime Technology Societies); IMAM, International Maritime Association of the Mediterranean and since 1980 organizes High Speed Marine Vehicles Conference arrived at 13th edition.

From the point of view of the experimental structures, the marine hydrodynamic laboratory (Laboratorio Esperienze Idrodinamica Navale LEIN) was strengthened with the installation, in the years from 2004 to 2006, of a new data acquisition system and of a wavemaker equipment capable of generating waves with high precision.

The Department of Industrial Engineering was born on 1 January 2013 with the confluence of professors and researchers belonging to the dissolved departments.

Fig. 1
A photograph of a multihull ship model tested in a water tank with measuring devices attached to the model via a steel frame from above.

Example of a multihull

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3 Evolution

In the last ten years, the group of professors and researchers engaged in the fields of Naval Architecture and Marine Engineering has been decisively renewed. Currently, it is made up of 14 members including professors, researchers, and specialized technicians.

Thanks to the possibilities offered by the new departmental structure, there was an enrichment of the research topics with the establishment of profitable synergies with other scientific sectors. For example, the collaborations in the field of self-driving airships, in that of ship propulsion with the use of new energy sources, in the study of methodologies for the use of marine renewable energies.

The development of the topics has been accompanied by the constant adaptation and strengthening of laboratory equipment and with the planning of new structures, like a fuel cells lab.

These activities have also had important repercussions in the educational field: just mention the Erasmus Master Mundus Joint Master Degree Sustainable Ship and Shipping 4.0, delivered together with the University of A Coruna, University of Zagreb and Technical University of Hamburg and coordinated by DII professors; and the recent BIP course Seakeeping and Stabilization of Large Yachts, delivered together with the CMC Marine; the collaborative activity within the Erasmus KA2 ShipMartech project, “Upgrading and Harmonization of Maritime Engineering Master’s Level Courses”, coordinated by the Technical University Tallinn, Estonia, with the University of Zagreb Faculty of Mechanical Engineering and Naval Architecture and University of Aegeo, on the harmonization of Naval Engineering courses; all initiatives that have projected the teaching of the NAME group into the international field.

Numerous international conferences: STAB, FAST, IMAM, International Hydrodynamic Conference have been hosted and organised. Conference High Speed Marine Vehicles Conference has started in 1991 and since that every three years is organised by the professors of NAME group, under the patronage of the Università degli Studi di Napoli “Federico II”, Royal Institution of Naval Architects, UK and Marina Militare Italiana.

4 Main Research Programmes

4.1 Hull Performance and Shape Optimization

The relationship between hull shapes and hydrodynamic performances and powering prediction in calm water has been always one of the main research topics in Marine Hydrodynamics group. The group strongly believe in synergy of experimental and numerical approach. The research activities on the hull shape optimization have been focused primarily on two areas: multihulls and monohulls: displacing, planing, and semi-planing [1,2,3]. The research is conducted experimentally in a towing tank [3,4,5] and via numerical simulations (by Computational Fluid Dynamics simulations). The behaviour of the vehicles, both in still and rough water, is analysed, [6,7,8,9,10]. Regarding planing and semi-planing vessels, in addition to systematic studies to identify the best hull forms, the effectiveness of conventional and unconventional high lift devices has been investigated. The research on multihulls was focused on catamarans, trimarans, and SWATHs. In particular, the hydrodynamic interferences between the demi-hulls have been systematically analysed, looking into the effects of clearance and stagger variations and asymmetries of both the demi-hulls and the entire catamarans.

On this topic, numerical tools have been largely used to explore the design space with different approaches (e.g., Design of Experiment, Surface responses, etc.) and identify the optimal hull shape (Fig. 2).

Fig. 2
A photograph and a spectral image depict the wetted surface area of the stepped hull model, with the wetted surface indicated by different shades.

Wetted surface of a stepped hull: comparison numerical versus experimental [8]

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4.2 Low Environmental Impact Ships

4.2.1 Integration of Electrical Propulsion Systems Onboard Ships

Electrical propulsion systems are currently used on many types of ships for their advantages in terms of comfort, operational flexibility and controllability. In addition, the hybrid or all electric can achieve also significant reduction in noxious and greenhouse gas emissions.

The integration of storage devices requires the development of energy management procedures that impact the sizing and efficiency of the various components. The challenge is to find the solution to optimal problems subject to different types of constraints.

The theoretical activities are accompanied by an experimental activity in collaboration with the Italian National Research Council, to verify the robustness and the optimality of the control of power flows between sources, batteries, supercapacitors and loads (Fig. 3).

Fig. 3
A photograph of a measuring device attached to the diesel engine with connecting wires.

Measuring the performance of a diesel engine powering a pleasure boat

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4.2.2 Emissions from Ships in Port

The problem of emissions from ships in areas close to inhabited zones is one of the most urgent items.

Nowadays, placing ports in crucial positions, especially in large seaside cities, is very attractive for tourism and trade as it is unquestionably suggestive to get off a cruise ship and find yourself right in the center of the city to visit. However, these ships have a great impact on the environment, since, in order to satisfy the hull and hoteling utilities active on board, they must produce very high power with consequent significant exhaust emissions.

This line of research is dedicated to the assessment of emissions from ships (with particular attention to cruise ships) and to the development of devices that would reduce the environmental impact of these emissions on the port environment. It is based on direct measurements of emissions onboard, analysis and post processing of AIS (Automatic Identification System) data, assessment of the emissions using internationally accepted routines of evaluation and reconstruction of the overall quantities of harmful elements emitted in the air [11, 12].

4.2.3 Overall Impact of the Marine Activity on the Ports of Water Cities

Alongside the study of emissions from ships, another thread of research could be the evaluation of the influence of any source of pollution (including ships, of course) on the quality of the air in port with a particular interest in determining the so-called apportionment, i.e., the exact responsibility of each source of pollution on the healthiness of the air.

This research necessarily involves numerous and accurate measurements in order to have a reasonable knowledge of the contents of harmful elements in the air and their change according to the various phases of the life of the port [13] (Fig. 4).

Fig. 4
Two images. a. A photograph of electronic devices stacked in a steel rack. b. A photograph of different sensors installed on top of a van.

The instrumentation used for revealing the contents of the air in port (left) and the equipped van with sensors (right)

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4.2.4 Transport Phenomena in Ballast Water Management

The systems of ballast water management move very large quantities of water and they are exposed to various kinds of problems. One of these problems consists in the introduction of many elements carried by the flow of the water entering in the double bottoms. Among them, bacteria, living aquatic species, metals, debris and everything that can be gathered from the sea water or produced inside the chests.

In the phase of discharging of the ballast water from the double bottoms, due to the effect of the incrustations formed under the water intake points, debris may be sucked in, end up running along the entire ballast piping and entering in ballast pumps with potential damage to the moving parts of the latter.

For these reasons, the transport phenomena linked to the detachment of debris under the water intake points and their entry into the ballast piping are studied using a particular system that simulates the real ones installed on board ships to reconstruct with remarkable precision the trajectory of all the particles that detach from the bottom due to the effect of the overlying water flow, to understand the dynamics that move them and to develop systems capable of avoiding the damage potentially caused to pipes, components and pumps [14].

4.2.5 Modeling of Marine Diesel Engines

Another line of research active in our field regards the simulation approach to ship propulsion systems. This line of research involves purely mechanical aspects such as the simulation of marine engines and more generic approaches to innovative on-board power generation systems.

In particular, engine simulation is approached with cutting-edge simulation tools, with commercial software and/or built in the MATLAB/Simulink environment: the former, though requiring greater levels of detail about the individual components and the laws governing heat transfer, losses, turbo group dynamics, and combustion in the cylinders, allow an estimation of atmospheric pollutant emissions. The latter class of models, on the other hand, allows for broad-spectrum results about classic engine performance in slightly less detail [15].

Two-stroke, four-stroke, small, medium and large engines are taken into consideration, working with traditional or alternative fuels; energy recovery, efficiency, dual fuel engines and, in the near future, Fuel Cell, and methanol fueled engines will complete this line of research.

New frontiers in this area are the simulation of engines powered by alternative fuels such as natural gas and methanol, and the use of simulation models to set up an engine digital twin model capable of monitoring and fault diagnostics.

4.3 Sea Keeping and Structural Loads

Seakeeping embodies knowledge of three fields: probabilistic description of environment (wave, wind, current and geographical area) in which ship or offshore structure will operate, deterministic responses of ships in regular waves and seakeeping performance criteria intended as the established limits for the ship’s responses [16,17,18].

First numerical methods, developed in fifties of the 20th century, are based on the linearised physics of the phenomena and improving of mathematical models is very active research area. From nineties, professors and researchers of NAME are working on the improvement of frequency domain codes, development of weakly nonlinear time domain simulations for the displacement ships and fully nonlinear prediction of planing crafts to assess structural loads and motions [19,20,21].

Since 2006, Marine Hydrodynamic Laboratory has been equipped by wavemaker and researchers enriched their portfolio with the expertise in experimental seakeeping of planing craft, both in terms of highly nonlinear phenomena for the loads assessment as well as comfort assessment on board of pleasure boats, or working conditions on board [22].

4.4 Ship Propulsion

The topic of ship propulsion investigated at the NAME group of the DII can be divided into conventional and unconventional ship propulsion (Fig. 5).

Fig. 5
A photograph of a ship model being tested by a group of engineers inside a laboratory building.

1001 Vela Indoor Challenge Trophy 2018

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Regarding conventional ship propulsion, the investigation focused more on the analysis of the interaction between the hull and propeller than the propeller itself.

The interaction between the hull and propeller, as well as the optimization of hull resistance, are the two pillars of optimizing hull performance which has become increasingly important in recent years due to the increased effort to reduce the environmental impact of the maritime transport system. The hull-propeller interaction has been investigated mainly through experimental tests and numerical (Computational Fluid Dynamics) simulations using different propeller models (e.g., Actuator disk, Blade Element Theory or Actual propeller geometry) [23] (Fig. 6).

Regarding the unconventional propulsions, on the other hand, the investigations were more focused on Wind Assisted Ship Propulsion (WASP), specifically on the characterization of the Flettner rotor performances by systematically varying shapes and sizes and the interaction between the Flettner rotor and the whole conventional ship propulsion system [24].

Fig. 6
A photograph of a ship model being tested in a water tank with sensors attached to the model via a steel frame from above.

Measurement of the pressure distribution on the bottom of planing hull

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4.5 Ship Stability and Safety

4.5.1 Second Generation Intact Stability Criteria

The stability criteria are the requisites that ships must accomplish to ensure an adequate level of safety against the risk of capsizing, regulated by the International Maritime Organization (IMO), the specialized agency of United Nations with responsibility for the safety and security of shipping and the prevention of marine pollution by ships. The first set of the stability criteria are based on the statistical elaboration of the survived ships and are empirical formulation giving limiting values for the most important parameters which affects ship stability, as proposed in Rahola (1935). After numerous stability failures of intact ships in waves, IMO working group started development of the so called “second generation intact stability criteria” in which the most advanced nonlinear numerical simulations can be used for the direct assessment of the ship dynamics. Phenomena like parametric roll, surf riding, pure loss of stability and excessive acceleration are considered in the probabilistic frame of their occurrence. In this context, the group has given significant contributions, reported in prestigious international journals [25].

4.5.2 Damage Stability and Flooding Analysis

The study of damaged stability is required to ensure the survivability of damaged ships after the accidental flooding of one or more compartments.

The damage stability criteria, as for intact stability, are regulated by the IMO. Currently, two approaches are available at the scope: probabilistic and deterministic damage stability. Probabilistic damage stability is a methodology based on accident statistics on ship-ship collisions and involves some degrees of uncertainty- Deterministic methodology, instead, works on a predefined set of damage scenarios. The research group gave a significant contribution in this context, following also the global research trend on the topic.

Nowadays, time-domain simulations of flooding and motions of damaged ships are more frequently performed to obtain a more realistic overview of the actual survivability in case of a flooding accident. Therefore, the research group currently focuses on the understanding of flooding mechanisms and on the response in terms of ship dynamics by means of experimental tests and numerical simulations [26].

The outcomes of these research activities, together with the participation in a relevant benchmark study on numerical simulation of flooding and motions of a damaged ship, are reported in international journals [27, 28] (Fig. 7).

Fig. 7
A photograph of a damaged ship model floating in water with the motions of the model measured using sensors.

Experimental study of damaged DTMB 5415 naval vessel

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4.6 Ship Structural Analysis—Noise and Vibrations

Shipping has played a central role in transportation and trade with about 90% of internationally traded goods carried by ships. Simultaneously, with the growth in demand for ships and an increase in their complexity, ship structural design and calculation procedures have advanced considerably from prescriptive rules of the classification societies to rational analysis and design methods (Fig. 8).

Fig. 8
A photograph displays a dock where a ship is being built, with a massive crane putting the ship's parts together.

View of a ship under construction in a dry-dock

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In this context, the marine engineering section of the Industrial Engineering Department carried out research and studies on the four tasks that identify a rational structural design process:

  1. 1.

    Calculation of environmental loads;

  2. 2.

    Overall and substructure response analysis;

  3. 3.

    Limit state analysis;

  4. 4.

    Formulation of reliability-based structural constrains.

Several methods and tools for the assessment of loads and load effects were developed together with methods for the strength assessment of the hull girder [29]. Moreover, structural reliability, safety and environmental protections were the core topics of several researches [30].

Fig. 9
A photograph of a microphone mounted on a tripod placed on the platform with a ship in the background.

Experimental measurements of noise from ships

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4.6.1 Noise from Ships

The NAME group of the Industrial Engineering Department, gave great attention also to the problem of Ship noise and vibrations. These can originate from a variety of sources on board, (including auxiliary engine exhausts, engine room and hold ventilation systems) and have negative impacts in terms of acoustic pollution, in air and in water. A research program was established, aiming at studying the noise levels of the ships and the possible solutions to the problem. A line of research has been treating the noise radiated into the air by ships, especially passenger ships, when engaged in port activities. In particular, the problem was approached from two sides; the first implied experimental measurements on board and in port by using sound level meters and intensimetric sound probes; the second is a simulative approach that, by ray tracing models, takes into account the countless sources of noise on board, the orography of the area, the buildings present and estimates the transmission of noise in the air that impacts the port city [31] (Fig. 9).

5 Future

Realistically, the marine field will undergo a number of significant changes. There is an urgent need to reduce the environmental impact of the operations of ships in all phases of navigation and, particularly, when the ship is in port. Indeed, since the power released by the engines of large ships is huge, the emissions are correspondingly high. For these reasons, rules and regulations are in progress to reduce the environmental impact of marine engines, above all, during working in ports i.e., close the inhabited zones. Probably, the reduction of emissions from ships will be achieved on various fronts and it will involve different solutions. The use of alternative fuels—such as methanol, liquid methane, LPG, and other fuels—will be further developed together with more radical solutions like the application of fuel cells onboard; this will certainly be achieved but the path towards a truly applicable solution is still long and difficult because the research in this field will have to overcome the problems associated with the production and use of hydrogen on board with all its operational and safety risks.

Autonomous and smart vessels, as in other fields of self-traction vehicles, are under study in order to create ocean-going cargo ships capable of navigating without crew, aiming at generating a significant money saving in the management of the ship and a remarkable improvement in the safety of the navigation. Indeed, the challenge of the researchers in the field is to ensure an adequate level of safety of the autonomous vessel, accounting for the peculiar environment where the ship operates.

The future research topics will also focus on the effects of climate change on the estimation of environmental actions, such as those from wind, waves, and currents, and their consequences on all maritime activities. Changes in ocean wave climate are expected to affect the extreme waves and rogue waves occurrence, demanding an upgrade in the structural design of ships and off-shore structures.

The future research of the professors and researchers of NAME group will further boost the bond of our expertise in experimental and numerical approaches to achieve highly sustainable ships. This synergic approach provides a proper insight on the hydrodynamic phenomena, provides additional information to experimental results not easily measurable and assures validation of CFD simulations. Future research will continue the optimization of the hull forms for zero-emission and energy-saving devices with high fidelity tools through the coupled CFD and FEM methods (e.g., Fluid-Structure Interaction) and the application of mesh-less or mesh-free codes such as Smoothed Particles Hydrodynamics (SPH) and Moving Particle Semi-implicit (MPS) methods. Research on the development of weakly nonlinear simulations in 6 DoF for complex hydrodynamic phenomena for safety and loads assessment will continue within the regulatory framework of Second Generation Intact Stability Criteria and research on the performances of wave energy converters.

The synergic combination of the developed numerical models will allow the simulation of hull-propeller—engine interactions, providing a digital twin of the whole propulsion chain of the ship in different scenarios. The adoption of digital twins, as in other fields, is gathering great attention for future applications aiming at enhancing the safety, efficiency, and sustainability of ship systems.