Experimental and Numerical Modelling of an Offshore Aquaculture Cage for Open Ocean Waters

2018 ◽  
Author(s):  
Alfonso Jurado ◽  
Patricia Sánchez ◽  
Jose A. Armesto ◽  
Raúl Guanche ◽  
Bárbara Ondiviela ◽  
...  
Keyword(s):  
Numerical Model ◽  
Time Domain ◽  
Environmental Conditions ◽  
Ad Hoc ◽  
Experimental Tests ◽  
Ocean Basin ◽  
Open Ocean ◽  
Offshore Aquaculture ◽  
Decay Tests ◽  
Multi Body

An innovative offshore aquaculture cage design and its hydrodynamic behavior for different environmental conditions is presented. The work involves the following blocks: (i) design of the aquaculture cage, (ii) experimental tests performed at IHCantabria facilities (Cantabria Coastal and Ocean Basin, CCOB), (iii) brief description of the ad-hoc time domain numerical model developed, and (iv) calibration of decay tests and sea states cases, in order to be able to simulate different locations of interest for aquaculture stakeholders. The offshore aquaculture cage is a floating cylindrical structure, designed according to different requirements from standards and needs of contacted aquaculture stakeholders. The cage is focused on the growing and farming of fish species in open ocean conditions. It has been specially designed to be able to withstand different environmental conditions, even waves of more than 5m height. Through numerical and physical modeling, it has been shown that it has a good seakeeping and accessibility, to reduce O&M costs. Motions and loads have been registered during the tank testing to calibrate and validate a specific coupled time domain numerical model developed for multi-body structures to simulate the behavior of the assembled structure (cage and sinker connected by tendons), including non-linear damping forces and a FEM approach to model the mooring and the tendon system.

Calibration of a Time-Domain Hydrodynamic Model for A 12 MW Semi-Submersible Floating Wind Turbine

2021 ◽  
Author(s):  
Carlos Eduardo Silva de Souza ◽  
Nuno Fonseca ◽  
Petter Andreas Berthelsen ◽  
Maxime Thys
Keyword(s):  
Numerical Model ◽  
Wind Turbine ◽  
Time Domain ◽  
Quadratic Model ◽  
Wave Loads ◽  
Frequency Wave ◽  
Load Models ◽  
Wave Drift ◽  
Floating Wind Turbine ◽  
Decay Tests

Abstract Design optimization of mooring systems is an important step towards the reduction of costs for the floating wind turbine (FWT) industry. Accurate prediction of slowly-varying horizontal motions is needed, but there are still questions regarding the most adequate models for low-frequency wave excitation, and damping, for typical FWT concepts. To fill this gap, it is fundamental to compare existing load models against model tests results. This paper describes a calibration procedure for a three-columns semi-submersible FWT, based on adjustment of a time-domain numerical model to experimental results in decay tests, and tests in waves. First, the numerical model and underlying assumptions are introduced. The model is then validated against experimental data, such that the adequate load models are chosen and adjusted. In this step, Newman’s approximation is adopted for the second-order wave loads, using wave drift coefficients obtained from the experiments. Calm-water viscous damping is represented as a linear and quadratic model, and adjusted based on decay tests. Additional damping from waves is then adjusted for each sea state, consisting of a combination of a wave drift damping component, and one component with viscous nature. Finally, a parameterization procedure is proposed for generalizing the results to sea states not considered in the tests.

Numerical and Experimental Study of a Multi-Use Platform

2016 ◽  
Author(s):  
José A. Armesto ◽  
Javier Sarmiento ◽  
Víctor Ayllón ◽  
Arantza Iturrioz ◽  
Alfonso Jurado ◽  
...  
Keyword(s):  
Numerical Model ◽  
Time Domain ◽  
Laboratory Tests ◽  
Power Production ◽  
Ocean Basin ◽  
Mooring System ◽  
Nonlinear Friction ◽  
Friction Forces ◽  
Static Approach ◽  
Hydrodynamic Study

A complete hydrodynamic study of a Multi Use Platform designed to harvest energy from waves and wind is presented. The steps given in the study, and presented in this paper are: (i) the design of the platform, (ii) the laboratory tests performed at the Cantabria Coastal and Ocean Basin, (iii) the development of a new in-house time domain numerical model that integrates all components and (iv) the first validation cases of the numerical model. The development of time domain numerical model that coupled the behaviour of the platform and the OWCs based in Cummins equation is presented. The model includes nonlinear friction forces and a quasi-static approach to model the mooring system. The obtained system is extended to include the variation of the pressure inside each chamber. The effect of the wind turbine in the movements and power production of the platform is studied using also a quasi-static approach.

Vibration Monitoring for Local Fault Detection in Synchronous Belts

2008 ◽  
Author(s):  
Roberto Basso ◽  
Giulio Fanti
Keyword(s):  
Numerical Model ◽  
Frequency Spectrum ◽  
Test Bench ◽  
Power Spectra ◽  
Experimental Tests ◽  
Vibration Monitoring ◽  
Signal Acquisition ◽  
Motion Sensors ◽  
Belt Transmission ◽  
Multi Body

The possibility of diagnosing the presence of a fault in a synchronous belt transmission during its work, without dismantling it, by monitoring the vibrations of the pulley support, was investigated in this work. After a few simulations with a multi-body numerical model, several experimental tests were carried out in an apparatus made up of a test bench, motion sensors, a system of signal acquisition and software for data processing. The behavior of mechanical transmissions with healthy and faulty synchronous belts was compared. The damage was simulated by removing a tooth from the belt. The results show that a localized defect on a synchronous belt modifies the frequency spectrum of the motion signals measured on the pulley support. From the experimental tests performed, the following results were obtained: the direction of vibrations measured on the pulley support must be chosen so as to be parallel to the direction of the taut side of the belt; the presence of a defect can be seen in the frequency spectrum by the change in the amplitude of the peaks at the first harmonics of the run frequency; the best condition to highlight the different behaviour in the power spectra occurs when the transmission is under load.

Drift-Off Study in Drilling Vessels Comparing Numerical Model and Full-Scale Field Measurements

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Eduardo A. Tannuri ◽  
Pedro C. de Mello ◽  
Raul Dotta ◽  
Anderson T. Oshiro ◽  
Gustavo R. Diederichs ◽  
...  
Keyword(s):  
Numerical Model ◽  
Time Domain ◽  
Environmental Conditions ◽  
Emergency Situation ◽  
Field Measurements ◽  
Full Scale ◽  
Large Set ◽  
System Failures ◽  
Environmental Disasters ◽  
Drift Trajectory

Abstract In drilling vessels, the dynamic positioning (DP) system has a great importance for the operation, since it ensures the station-keeping ability for the drilling operation. However, an emergency situation involves ungoverned drift due to problems associated with the DP system failures, such as thrusters, generators, powerbus, or control system. During this situation, the vessel drift is subjected to the influence of environmental conditions and the drift can lead to collisions with floating obstacles or submerged systems, wellhead emergency disconnection, damage to equipment and potentially causing major environmental disasters. It is then necessary to define a safety region for the drilling ship operation and to determine the limiting operation offset that the drilling vessel can disconnect from the wellhead without damage to any equipment. This offset limit is obtained through a riser analysis and drift-off study, important inputs for the Well Specific Operating Guidelines (WSOG). A validated time-domain simulator is required and able to predict the vessel drift trajectory after the DP failure under several environmental conditions. The aim of this work is to present a large set of model and full-scale drift tests and the validation of a time-domain numerical simulator (Dynasim), based on the main parameters of the drift tests: drift distance, heading variation, and trajectory. The comparisons between the numerical simulation results with full- and model-scale data demonstrated the accuracy of the numerical model, confirming that the simulator is a reliable tool to predict the motion of a drilling vessel after a blackout.

TELWIND: Numerical Analysis of a Floating Wind Turbine Supported by a Two Bodies Platform

2018 ◽  
Author(s):  
José A. Armesto ◽  
Alfonso Jurado ◽  
Raúl Guanche ◽  
Bernardino Couñago ◽  
Joaquin Urbano ◽  
...  
Keyword(s):  
Numerical Model ◽  
Wind Turbine ◽  
Large Scale ◽  
Ad Hoc ◽  
Numerical Study ◽  
Coupled Model ◽  
Ocean Basin ◽  
Full Description ◽  
Aerodynamic Model ◽  
Floating Wind Turbine

This paper presents a numerical study of an innovative floating wind turbine developed by ESTEYCO S.A.P. as part of an intensive R&D roadmap initiated ten years ago. The concept is called TELWIND, an evolved spar concept composed by a telescopic tower and two independent concrete bodies: the upper tank (acting as buoyancy body) and lower tank (acting as ballasting body), connected by suspension tendons. An ad-hoc numerical model has been developed by IHCantabria, calibrated and validated, based on a set of large scale laboratory tests performed at the Cantabria Coastal and Ocean Basin (CCOB), located at IHCantabria, Santander, Spain. The inhouse numerical model is a fully coupled model which comprehends three main modules: i) Hydrodynamic model that analyses the coupled hydrodynamics of floater and ballast. ii) Mooring and tendon module, and iii) Aerodynamic model. The full description of the numerical model is summarized, as well as the validation procedure followed. Finally, the validation of the numerical model is shown.

Tensegrity Structures in the Design of Flexible Structures for Offshore Aquaculture

2007 ◽  
Author(s):  
O̸sten Jensen ◽  
Anders Sunde Wroldsen ◽  
Pa˚l Furset Lader ◽  
Arne Fredheim ◽  
Mats Heide ◽  
...  
Keyword(s):  
Flexible Structures ◽  
Weather Conditions ◽  
High Energy ◽  
Open Ocean ◽  
Element Analysis ◽  
Tensegrity Structures ◽  
Stiffness Properties ◽  
Offshore Aquaculture ◽  
And Performance ◽  
Open Ocean Aquaculture

Aquaculture is the fastest growing food producing sector in the world. Considerable interest exists in developing open ocean aquaculture in response to a shortage of suitable, sheltered inshore locations. The harsh weather conditions experienced offshore lead to a focus on new structure concepts, remote monitoring and a higher degree of automation in order to keep the cost of structures and operations within an economically viable range. This paper proposes tensegrity structures in the design of flexible structures for offshore aquaculture. The finite element analysis program ABAQUS™ has been used to investigate stiffness properties and performance of tensegrity structures when subjected to various forced deformations and hydrodynamic load conditions. The suggested concept, the tensegrity beam, shows promising stiffness properties in tension, compression and bending, which are relevant for development of open ocean aquaculture construction for high energy environments. When designing a tensegrity beam, both pre-stress and spring stiffness should be considered to ensure the desired structural properties. A large strength to mass ratio and promising properties with respect to control of geometry, stiffness and vibration could make tensegrity an enabling technology for future developments.

scholarly journals Elasto-plastic-adhesive DEM model for simulating hillslope debris flows: cross comparison with field experiments

2018 ◽  
Author(s):  
Adel Albaba ◽  
Massimiliano Schwarz ◽  
Corinna Wendeler ◽  
Bernard Loup ◽  
Luuk Dorren
Keyword(s):  
Numerical Model ◽  
Flow Velocity ◽  
Debris Flows ◽  
Field Experiments ◽  
Initial Conditions ◽  
Experimental Tests ◽  
Height Velocity ◽  
Model Parameters ◽  
Fine Content ◽  
Adhesive Model

Abstract. This paper presents a Discrete Element-based elasto-plastic-adhesive model which is adapted and tested for producing hillslope debris flows. The numerical model produces three phases of particle contacts: elastic, plastic and adhesion. The model capabilities of simulating different types of cohesive granular flows were tested with different ranges of flow velocities and heights. The basic model parameters, being the basal friction (ϕb) and normal restitution coefficient (ϵn), were calibrated using field experiments of hillslope debris flows impacting two sensors. Simulations of 50 m3 of material were carried out on a channelized surface that is 41 m long and 8 m wide. The calibration process was based on measurements of flow height, flow velocity and the pressure applied to a sensor. Results of the numerical model matched well those of the field data in terms of pressure and flow velocity while less agreement was observed for flow height. Those discrepancies in results were due in part to the deposition of material in the field test which are not reproducible in the model. A parametric study was conducted to further investigate that effect of model parameters and inclination angle on flow height, velocity and pressure. Results of best-fit model parameters against selected experimental tests suggested that a link might exist between the model parameters ϕb and ϵn and the initial conditions of the tested granular material (bulk density and water and fine contents). The good performance of the model against the full-scale field experiments encourages further investigation by conducting lab-scale experiments with detailed variation of water and fine content to better understand their link to the model's parameters.

Experimentally calibrated simplified time-domain numerical model for a multi-chamber OWC device

2015 ◽  
pp. 463-469
Author(s):  
A Iturrioz ◽  
J Sarmiento ◽  
J Armesto ◽  
R Guanche ◽  
C Vidal ◽  
...  
Keyword(s):  
Numerical Model ◽  
Time Domain
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