Energy Presentations

Download user presentations that focus on applications of FLOW-3D for the energy industry from past users conferences.

2019

Numerical modelling of a two-degree-of-freedom Wave Energy Converter: Creation, validation and utilization of the model

Eliseo Marchesi, Politecnico di Milano/Studio Frosio srl
Marco Negri and Stefano Malavasi, Politecnico di Milano
Filippo Palo, XC Engineering S.r.l.

The aim of this study is the numerical modelling, through FLOW-3D, of a particular Wave Energy Converter (WEC) that has been subject of laboratory-scale tests at Politecnico di Milano: the Energy Double System (EDS), a two degree-of-freedom oscillating-body system, composed of a heaving float and a surging paddle. The two bodies are interconnected and each of them is connected to a Power Take-Off (PTO) that reacts against the ground. The numerical model has been verified against available experimental tests with periodic waves. The first simulations have been aimed at reproducing the periodic waves of the laboratory tests. Then, a numerical model of the EDS equivalent to the experimental system has been created, and it has been subjected to the previously modeled periodic waves. Once the quality of the numerical method has been verified, simulations of new configurations of the EDS system have been carried out. In a first series of simulations, the damping of the paddle PTO has been varied in order to optimize it, since this parameter was not optimized in the experimental model. Subsequently, the EDS behavior has been investigated in random waves that are energetically equivalent to the previously simulated periodic waves.

2015

Numerical simulation of extreme wave loading on an axisymmetric point absorber wave energy converter in a survival sea state

Peter Arnold, Minerva Dynamics Limited

An early assessment of the forces and moments likely to be experienced by a wave energy converter (WEC) in survival sea states is of particular importance during the concept design phase. To date, the main method used to assess survivability for WEC’s is model scale tank testing, however due to the size of the survival waves, which typically have a significant wave height in the range of 10m to 15m, tank testing programmes must either use small scale prototypes, with their associated instrumentation and physical scaling issues, or else resort to larger scale prototypes, with their associated larger costs. More recently CFD has been used to assess non-linear wave loading on static and floating structures using solitary focused or “New Waves,” as opposed to irregular wave spectrums due to the smaller computational costs. However these initial studies only provide necessary but not sufficient conditions for WEC survival, as statistical distributions of the resulting loads are required by WEC designer engineers. The aim of this study is to re-distribute the importance attached to the modelling assumptions in the CFD model by utilising an irregular wave spectrum with a reduced number of spectral components and level of mesh refinement and wave tank width in an attempt to obtain a solution in a reasonable time scale. The resulting WEC motions and loads are then compared to high fidelity tank test results of the survival of a 35th scale axisymmetric point absorber in terms of key statistical parameters.

Wave propagation and reflection at an inclined plane – simulations and experiments

Boris Huber, Vienna University of Technology

Physical model tests were conducted in a 20 m long flume to observe wave propagation and reflection at an inclined plane at the end of the flume. Wave generation was done with a paddle mounted at the bottom moving forwards and backwards driven by an extender wheel. The propagation of the waves was recorded at several points by water level measurements. The experiments were run with many different waves and then simulated with FLOW-3D. Furthermore, experiments with a wave-absorbing boundary consisting of stones and perforated sheets were carried out and simulations run with different boundary conditions in order to gain a suitable boundary condition in the CFD simulation.

2013

Flap type wave power device in near shore conditions

Stephen Saunders, Ibis Group, Inc

A CFD analysis of a single moving flap wave power capture device has been performed using FLOW-3D v10.1 as the solution code. The purpose of this undertaking is to predict the forces encountered by the flap in its intended working environment prior to construction and deployment of a prototype. FLOW-3D was selected for this project above its competitors because of the robust VOF model needed for capturing the dynamics of the moving air/water interface. Moreover, FLOW-3D‘s FAVOR™ method for representing moving solid objects is critical to simulating the flap in motion. The performance of the flap geometry was simulated and subsequently evaluated in what would be near shore conditions where oncoming waves are normal to the face of the flap. The models tested are constructed as 3-D in order to assess flow characteristics around the end of the flap. To date, two sea states have been tested. These are non-breaking swells and waves that are breaking just as they reach the flap. The non-breaking swells, as expected, induce a smooth flap motion that is nearly symmetrical with equal flap deflections on either side of neutral. Results from breaking wave cases are much more dramatic with asymmetric motion and loadings.

Ocean waves resonance analysis of an oscillating water column energy converter

José Manuel Grases; Sendekia

SDK Marine is developing a new way to gather electrical energy from ocean waves based in a hydraulic turbine immersed in water within an oscillating water column chamber. FLOW-3D was used to understand flow behavior inside and outside the chamber. The main goal of the project was to obtain the response of the device by measuring the inside water level and comparing it with the outside wave excitation. As well, different porous membranes were implemented in order to simulate the behavior of different hydraulic turbines in order to calculate hydraulic power on the device.