Simulators

The Maritime Technology Division of UGent uses the two maritime simulators (SIM360+ and SIM225) and one inland simulator (LARA) owned and developed by Flanders Hydraulics (FH) to conduct accessibility studies. Those simulators include the following mathematical manoeuvring model:

• calculation of hydrodynamic forces, shallow water effects, restricted (confined) water effects;
• propulsion;
• aerodynamic forces;
• contact forces and interaction with encountering and overtaking target vessels;
• effects of wind, waves and current.;

More info here.

VLUGMOOR: Simulating the behaviour of moored vessels

Description

Vlugmoor is used to calculate the behaviour of the moored vessel, under specific external loads. The software can handle input time series of wind, wave and current forces. Passing vessel forces are also modelled, using input from the commercial package RoPES [1]. The response of the moored vessel to these external influences is calculated in the time domain, in order to capture the non-linear nature of the vessel's response. Mooring lines and fenders are modelled, as are the ship's hydrodynamics. Both mooring at a quay and a jetty can be modelled.

[1] J.A.,Pinkster; H.J.M., Pinkster, 'A fast, user friendly, 3D potential flow program for the prediction of passing vessel effects', PIANC World Congress San Fransisco, 2014

Code specification

The code is at the moment exclusively used by the department, to perform mooring studies and research. The software is written in MATLAB language, using object oriented programming to make the code easy to rewrite in other computer languages. The advantage of this using this self-developed package is that it can be easily operated and modified, making it possible to include new modules to the code. The code is at the moment being fully overhauled as part of a PhD thesis.

Validation

The software has been validated successfully for passing ship effects, based on full-scale measurements performed at the port of Antwerp. Some of the results have been published at the PIANC World Conference 2018 in Panama [2]. The figures are taken from the referred paper, with on the left passing event at the North Sea Terminal in the port of Antwerp and on the right the surge motion of the moored vessel during the passing event, with a comparison between measured (GPS) and modelled motions. With the further development of the code, more validation work is planned in the near future.

[2] Van Zwijnsvoorde, T.; Vantorre, M; Ides, S, 'Container ships moored at the port of Antwerp : Modelling response to passing vessels', PIANC World Congress Panama City, 2018

Specific features

The code is not limited to only calculating time series of line forces and motions, it also allows post-processing, which can be finetuned to match project needs. For forces and motions due to cyclic wave action for example, the time series are converted to the frequency domain, to allow the calculation of significant and most probable maximum forces and motions, as well to identify possible resonance in the mooring system.

RIVSEA : Risk analysis estuary vessel at sea

Inland vessels are a key component in the connection between a (coastal) port and the hinterland. A good inland connection is not always available. In these cases, it might be opportunistic to perform a limited sea journey, under strict conditions, with well-equipped inland vessels. In Belgium, such traffic exists between the port of Zeebrugge and the mouth of the river Scheldt, allowing these so-called estuary vessels to reach Antwerp and travel further to neighboring countries. This is regulated by the Royal Decree for sea-going inland vessels [3]. According to this regulation, all inland vessels who want to perform estuary studies need to undergo a probabilistic sea-keeping analysis. Rivsea allows to calculate the response in waves of vessels, based on which a operational significant wave height is defined, by imposed risk limitations imposed by the Royal Decree.

Description

The Rivsea code is used to evaluate the risk of a inland vessel performing a sea journey. This is done according to the procedure outlined in [3] In a first step, the response of the vessel to incoming waves is calculated, based on the wave climate specification and the ship's response function (RAO). This is done for a representative period (e.g. 1 year measurement, with wave data every 2h), based on which the total number of exceedances of a given threshold response is calculated. Based on this risk assessment, the significant wave height up to which the vessel can operate is determined [4]. The figures show a spectral distribution of wave energy (left) and the ship response (RAO) to a unity wave height (center). The right figure shows the result of the risk analysis, giving a significant wave height up to which the vessel can operate. In this publication, a review of the sea-keeping analysis in the current legislation is given.[5]

[3] FOD, 'Koninklijk besluit betreffende binnenschepen die ook voor niet-internationale zeereizen kunnen worden gebruikt', Staatsblad 2013 [Dutch]

[4] Vantorre, M.; Eloot, K.; Delefortrie, G., 'Probabilistic regulation for inland vessels operating at Sea as an alternative hinterland connection for coastal harbours', EJTIR, 2012

[5] Donatini, L. et al.,'Belgian Royal Decree for sea-going inland vessels, a review for container and bulk cargo vessels', Pianc World Congress Panama City, 2018

Code specification

The calculation of ship responses for large data sets is performed using MATLAB, which is very efficient to handle large data matrices, performing calculations based on matrix manipulations. The code is written in a flexible way, where the core calculation core is written separately from the in- and output generation modules. This means that wave data can be imported from various locations, being either numerical hindcast results or measured wave data, and converted to the required input format. The software is suited to calculate the response for different variables (bending moment, relative motion) at different locations in a fast and efficient way, allowing to perform risk studies for a design vessel within acceptable time.

Specific features

The main advantages of the code are that it can handle different input wave sources and that it allows flexibility in the calculation. Next to the default calculation where the significant wave height is calculated up to which a vessel can operate, the need strength/freeboard can also be calculated for a target significant wave height, allowing to give valuable input to ship design.

Typhoon

Description

Typhoon is an open source free and easy to use software in which you can calculate any hydrofoil design. You get:

1. static force and moment calculation giving you forces, moments, as well as the overall lift and drag you get for a predefined forward speed, trim and elevation.
2. static equilibrium calculation (Newton Rhapson) gives you the trim and elevation which results in an equilibrium vertical force and moment around Y (external forces are assumed to be constant). For example, if more lift is needed for your mass, the trim will increase and/or your foils go deeper in the water (resulting in higher lift forces). The forces and moments you get are net forces so almost zero.
3. stability matrix indicating if the foiling ship is stable: If you give it a kick will it return to an equilibrium or get a nice splash? You need to like eigen values.

Please log on to the dedicated Typhoon website for more details about the code and tutorials on how to run it.

Happy foiling!