Simulation of mooring Lines in complex bathymetries using a finite element method

ABSTRACT: This paper presents a novel method for the modeling of the seabed interaction of mooring lines in complex bathymetries, known as "continuous projection method". This method is able to calculate ground normal and friction forces for any seafloor surface. This provides an improvement in the mooring systems simulation, as it captures additional non-linearities on the mooring line performance due to seabed interaction. The method is based on constructing a triangulation for the seabed and projecting mooring line nodes by using the vertex normal vectors of each triangle, ensuring the continuity of the projection. For the sake of the computational cost reduction, the line nodes are first projected into the closest triangles. Also, whenever the floor is flat, inclined or horizontal, a point-to-plane projection expression is used instead. The projection method described has been implemented to a finite element model. The initial condition problem was solved with a static approach, based on finding the static equilibrium with Newton-Armijo algorithm. This improves other static approaches which use the catenary equation, and that are only valid for a flat seabed. The model was successfully verified against the analytical solution of an inextensible catenary line in a slope. Furthermore, the simulation results were validated against experimental scale tests on a single chain mooring line with three different seafloor structures: one flat floor and two different sloped steps. For each of them, static and dynamic regular tests were performed. Moreover, high and low frequency fairlead movements were imposed in the dynamic tests, aiming to validate the model both in cases with and without snapping loads. Overall, the obtained results were coherent and allow to validate the accuracy of the proposed model. Finally, a mooring line over an irregular seabed surface was studied, comparing the results obtained by directly applying the developed method for complex bathymetries, by interpolating the surface by an inclined plane and using the constructed projection algorithm for that case or, by last, approximating by a flat seafloor. The comparison of the results among the different approaches illustrates the importance of considering the seabed slope and irregularities for the fairlead tension prediction. Also, this flat seafloor was evaluated with two different projection methods: the one specific for horizontal seafloors and the one developed for general seabed surfaces. This allows to compare the computational time required in both of them.This work is part of the COREWIND project which has received funding from the European Union’s Horizon 2020 Research and Innovation programme under grant agreement No 815083, as well as part of OASYS Project Grant PDC2021-121786-I00 funded by MCIN/AEI/ 10.13039/501100011033 and by the European Union Next Generation EU/PRTR. Also, Raul Guanche would like to acknowledge the funding received from the Ramon y Cajal 2017 research program. GrantRYC-2017-23260 funded by MCIN/AEI/10.13039/501100011033 and by ESF Investing in your future’’. All authors approved the version of the manuscript to be published

Simulation of Marine Towing Cable Dynamics Using a Finite Elements Method

A numerical model to study the towing maneuver for floating and submerged bodies has been developed. The proposed model is based on the dynamic study of a catenary line moving between two bodies, one body with imposed motion, and the other free to move. The model improves previous models used to study the behavior of mooring systems based on a finite element method by reducing the noise of the numerical results considering the Rayleigh springs model for the tension of the line. The code was successfully validated using experimental results for experimental data from different authors and experiments found in the literature. Sensitivity analysis on the internal damping coefficient and the number of elements has been included in the present work, showing the importance of the internal damping coefficient. As an example of the application of the developed tool, simulations of towing systems on a real scale were analyzed for different setups. The variation of the loads at the towed body and the position of the body were analyzed for the studied configurations. The reasonable results allow us to say that the proposed model is a useful tool with several applications to towing system design, study or optimizationThe authors are grateful to the Spanish Ministry of Economy, Industry and Competitiveness for funding ACOPLE- Analysis of the dynamic behavior of floating wind platforms for design optimization in deep waters (ENE2017-89716-R), within the National Programme for Research, Development and Innovation Aimed at the Challenges of Society (Call 2017). Raúl Guanche also acknowledges financial support from the Ramon y Cajal Program (RYC-2017-23260) of the Spanish Ministry of Science, Innovation and Universities

Plataforma semisumergible para aplicaciones en mar abierto

Una plataforma semisumergible que comprende: una columna interior y al menos cuatro columnas exteriores, donde cada una de dichas columnas interior y exteriores comprenden una base resistente y un tronco, y donde cada columna comprende una sección de mayor resistencia a una determinada altura y una pluralidad de vigas que unen cada columna exterior con la columna interior y cada columna exterior con cada columna exterior adyacente. Un método de construcción de una plataforma semisumergible.Solicitud: 201200760 (18.07.2012)Nº Pub. de Solicitud: ES2387232A1 (18.09.2012)Nº de Patente: ES2387232B2 (03.02.2014

Plataforma semisumergible triángular para aplicaciones en mar abierto

Una plataforma semisumergible que comprende: una columna interior configurada para dotar de mayor flotabilidad y tres columnas exteriores, donde cada una de dichas columnas interior y exteriores comprenden una base resistente y un tronco, y donde cada columna comprende una sección de mayor resistencia a una determinada altura y una pluralidad de vigas que unen cada columna exterior con la columna interior y cada columna exterior con las otras dos columnas exteriores. Un método de construcción de una plataforma semisumergible.Solicitud: 201200759 (18.07.2012)Nº Pub. de Solicitud: ES2387342A1 (20.09.2012)Nº de Patente: ES2387342B2 (10.02.2014

Dispositivo flotante offshore de acuicultura para el cultivo de diversas especies de peces

Dispositivo flotante de acuicultura para el cultivo de diversas especies de peces en mar abierto, que comprende: - dos cilindros huecos de igual radio interior y diferente radio exterior, de tal forma que la pared interior de ambos cilindros huecos está contenida en el mismo plano; - una placa de reducción y amortiguación de arfada unida a lo largo de todo el perímetro exterior de la base del cilindro hueco inferior: - una red de contención de especies de peces, que se conecta en un extremo a la parte inferior del cilindro hueco inferior y en el extremo restante a un lastre; - un lastre con forma de toroide, cuyo radio primario es igual al radio de la red de contención de especies de peces; - una pluralidad de tensores situados en la parte inferior del cilindro hueco inferior configurados para unir el lastre y dicho cilindro hueco inferior.Solicitud: 201600275 (06.04.2016)Nº Pub. de Solicitud: ES2578429A1 (26.07.2016)Nº de Patente: ES2578429B2 (18.04.2017

Physical and Numerical Modeling of an Innovative Vertical Breakwater for Sustainable Power Generation in Ports: SE@PORTS Project

This work has been supported by the OCEANERA-NET project, SE@PORTS (Sustainable Energy at Sea Ports); reference OCEANERA/0003/2016, under the frame of Sociedad para el Desarrollo Regional de Cantabria S.A. (SODERCAN)