Efficient response of an onshore Oscillating Water Column Wave Energy Converter using a one-phase SPH model coupled with a multiphysics library

In this paper the numerical modelling of an Oscillating Water Column (OWC) Wave Energy Converter (WEC) is studied using DualSPHysics, a software that applies the Smoothed Particle Hydrodynamics (SPH) method. SPH is a Lagrangian meshless method used in a growing range of applications within the field of Computational Fluid Dynamics (CFD). The power take-off (PTO) system of the OWC WEC is numerically modelled by adding a force on a plate floating on top of the free surface inside the OWC chamber. That force is implemented in the multiphysics library Project Chrono, which avoids the need of simulating the air phase that is computationally expensive in the SPH methods. Validation is carried out with experimental data received from the Korea Research Institute of Ship and Ocean Engineering (KRISO) and Ocean Energy Systems (OES) of the International Energy Agency (IEA) Task 10. The numerical and experimental water surface elevation at the centre of the OWC WEC chamber and the airflow speed through the orifice are compared for different wave conditions and different PTO systems (different orifice diameters at the top part of the chamber of the OWC WEC). Results show that DualSPHysics is a valid tool to model an OWC WEC with and without PTO system, even though no air phase is included.Research Foundation - Flanders | Ref. 1SC5421NXunta de Galicia | Ref. ED431C 2021/44Agencia Estatal de Investigación | Ref. IJCI-2017-3259

Development of Nano-Emulsions of Essential Citrus Oil Stabilized with Mesquite Gum

The use of nano-emulsions has great advantages over conventional macro-emulsions since the small droplet size allows to expand the options of applications besides presenting a greater surface area. This chapter focuses on the formulation of nano-emulsions of citrus essential oils in water, stabilized with a natural gum (mesquite gum), using a high pressure microfluidic homogenizer to obtain appropriate physicochemical characteristics and kinetic stability. When establishing the general conditions of the methods for obtaining nano-emulsions by high pressure homogenization, several formulations presented stability and size corresponding to nano-emulsions, and these were monitored during 4 months in order to study their stability as a function of time. Taking into account the results of size and stability, the best nano-emulsion obtained had a composition of Persian lemon oil (9.86%), mesquite gum (4.93%) Tween 80 (4.89%), Span 20 (1.45%), and deionized water (78.86%) with an average droplet size of 40 nm. In addition, the antibacterial activity studies also showed that this formulation had the best performance against common bacteria such as Staphylococcus aureus and Escherichia coli. The analysis of the minimum inhibitory concentration (MIC) shows that it is possible to prevent the growth of these particular bacteria using 6.25% of the best nano-emulsion formulations

Free-Surface Flow Simulations with Smoothed Particle Hydrodynamics Method using High-Performance Computing

Today, the use of modern high-performance computing (HPC) systems, such as clusters equipped with graphics processing units (GPUs), allows solving problems with resolutions unthinkable only a decade ago. The demand for high computational power is certainly an issue when simulating free-surface flows. However, taking the advantage of GPU’s parallel computing techniques, simulations involving up to 109 particles can be achieved. In this framework, this chapter shows some numerical results of typical coastal engineering problems obtained by means of the GPU-based computing servers maintained at the Environmental Physics Laboratory (EPhysLab) from Vigo University in Ourense (Spain) and the Tier-1 Galileo cluster of the Italian computing centre CINECA. The DualSPHysics free package based on smoothed particle hydrodynamics (SPH) technique was used for the purpose. SPH is a meshless particle method based on Lagrangian formulation by which the fluid domain is discretized as a collection of computing fluid particles. Speedup and efficiency of calculations are studied in terms of the initial interparticle distance and by coupling DualSPHysics with a NLSW wave propagation model. Water free-surface elevation, orbital velocities and wave forces are compared with results from experimental campaigns and theoretical solutions

A DEM approach for simulating flexible beam elements with the Project Chrono core module in DualSPHysics

This work presents a novel approach for simulating elastic beam elements in DualSPHysics leveraging functions made available by the coupling with the Project Chrono library. Such numerical frameworks, belonging to the Meshfree Particle Methods family, stand out for several features, like complex multiphase phenomena, moving boundaries, and high deformations which are handled with relative ease and reasonable numerical stability and reliability. Based on a co-rotating rigid element structure and lumped elasticity, a cogent mathematical formulation, relying on the Euler–Bernoulli beam theory for the structural discretization, is presented and applied to simulating two-dimensional flexible beams with the discrete elements method (DEM) formulation. Three test cases are presented to validate the smoothed particle hydrodynamics-based (SPH) structure model in both accuracy and stability, starting from an equilibrium test, to the dynamic response, and closing with a fluid–structure interaction simulation. This work proves that the developed theory can be used within a Lagrangian framework, using the features provided by a DEM solver, overtaking the initial limitations, and hence applying the results of static theories to complex dynamic problems.Xunta de Galicia | Ref. ED431C 2021/44Xunta de Galicia | Ref. ED481A-2021/337Ministerio de Ciencia, Innovación y Universidades | Ref. IJCI-2017-32592Agencia Estatal de Investigación | Ref. PID2020-113245RB-I0

GPUs, a new tool of acceleration in CFD: efficiency and reliability on smoothed particle hydrodynamics methods

Smoothed Particle Hydrodynamics (SPH) is a numerical method commonly used in Computational Fluid Dynamics (CFD) to simulate complex free-surface flows. Simulations with this mesh-free particle method far exceed the capacity of a single processor. In this paper, as part of a dual-functioning code for either central processing units (CPUs) or Graphics Processor Units (GPUs), a parallelisation using GPUs is presented. The GPU parallelisation technique uses the Compute Unified Device Architecture (CUDA) of nVidia devices. Simulations with more than one million particles on a single GPU card exhibit speedups of up to two orders of magnitude over using a single-core CPU. It is demonstrated that the code achieves different speedups with different CUDA-enabled GPUs. The numerical behaviour of the SPH code is validated with a standard benchmark test case of dam break flow impacting on an obstacle where good agreement with the experimental results is observed. Both the achieved speed-ups and the quantitative agreement with experiments suggest that CUDA-based GPU programming can be used in SPH methods with efficiency and reliability

Integration of UAV photogrammetry and SPH modelling of fluids to study runoff on real terrains

Roads can experience runoff problems due to the intense rain discharge associated to severe storms. Two advanced tools are combined to analyse the interaction of complex water flows with real terrains. UAV (Unmanned Aerial Vehicle) photogrammetry is employed to obtain accurate topographic information on small areas, typically on the order of a few hectares. The Smoothed Particle Hydrodynamics (SPH) technique is applied by means of the DualSPHysics model to compute the trajectory of the water flow during extreme rain events. The use of engineering solutions to palliate flood events is also analysed. The study case simulates how the collected water can flow into a close road and how precautionary measures can be effective to drain water under extreme conditions. The amount of water arriving at the road is calculated under different protection scenarios and the efficiency of a ditch is observed to decrease when sedimentation reduces its depth.Ministerio de Economía y Competitividad | Ref. BIA2012-38676- C03-0

Efficiency and survivability analysis of a point-absorber wave energy converter using DualSPHysics

Smoothed Particle Hydrodynamics (SPH) method is used here to simulate a heaving point-absorber with a Power Take-Off system (PTO). The SPH-based code DualSPHysics is first validated with experimental data of regular waves interacting with the point-absorber. Comparison between the numerical and experimental heave displacement and velocity of the device show a good agreement for a given regular wave condition and different configurations of the PTO system. The validated numerical tool is then employed to investigate the efficiency of the proposed system. The efficiency, which is defined here as the ratio between the power absorbed by the point-absorber and its theoretical maximum, is obtained for different wave conditions and several arrangements of the PTO. Finally, the effects of highly energetic sea states on the buoy are examined through alternative configurations of the initial system. A survivability study is performed by computing the horizontal and vertical forces exerted by focused waves on the wave energy converter (WEC). The yield criterion is used to determine that submerging the heaving buoy at a certain depth is the most effective strategy to reduce the loads acting on the WEC and its structure, while keeping the WEC floating at still water level is the worst-case scenario.Agencia Estatal de Investigación | Ref. ENE2016-75074-C2-1-RAgencia Estatal de Investigación | Ref. IJCI-2017-32592Xunta de Galicia | Ref. ED431C 2017/6

Coupling an SPH-based solver with an FEA structural solver to simulate free surface flows interacting with flexible structures

This work proposes a two-way coupling between a Smoothed Particle Hydrodynamics (SPH) model-based named DualSPHysics and a Finite Element Analysis (FEA) method to solve fluid–structure interaction (FSI). Aiming at having a computationally efficient solution via spatial adjustable resolutions for the two phases, the SPH-FEA coupling herein presented implements the Euler–Bernoulli beam model, based on a simplified model that incorporates axial and flexural deformations, to introduce a solid solver in the DualSPHysics framework. This approach is particularly functional and very precise for slender beam elements undergoing large displacements, and large deformations can also be experienced by the structural elements due to the non-linear FEA implementation via a co-rotational formulation. In this two-way coupling, the structure is discretised in the SPH domain using boundary particles on which the forces exerted by fluid phases are computed. Such forces are passed over to the FEA structural solver that updates the beam shape and, finally, the particle positions are subsequently reshuffled to represent the deformed shape at each time step. The SPH-FEA coupling is validated against four reference cases, which prove the model to be as accurate as other approaches presented in literature.Ministerio de Ciencia e Innovación | Ref. PID2020-113245RB-I00Ministerio de Ciencia e Innovación | Ref. TED2021-129479A-I00Xunta de Galicia | Ref. ED431C 2021/44Xunta de Galicia | Ref. ED481A-2021/337Universidade de Vigo/CISU

Coupling of an SPH-based solver with a multiphysics library

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGA two-way coupling between the Smoothed Particle Hydrodynamics-based (SPH) code with a multiphysics library to solve complex fluid-solid interaction problems is proposed. This work provides full access to the package for the use of this coupling by releasing the source code, completed with guidelines for its compilation and utilization, and self-contained template setups for practical uses of the novel implemented features, is provided here. The presented coupling expands the applicability of two different solvers allowing to simulate fluids, multibody systems, collisions with frictional contacts using either non-smooth contact (NSC) or smooth contact (SMC) methods, all integrated under the same framework. The fluid solver is the open-source code DualSPHysics, highly optimised for simulating free-surface phenomena and structure interactions, uniquely positioned as a general-purpose Computational Fluid Dynamics (CFD) software with a GPU-accelerated solver. Mechanical systems that comprise collision detection and/or multibody dynamics are solved by the multiphysics library Project Chrono, which uses a Discrete Element Method (DEM). Therefore, this SPH-DEM coupling approach can manage interactions between fluid and complex multibody systems with relative constraints, springs, or mechanical joints.Ministerio de Ciencia e Innovación | Ref. PID2020-113245RB-I00Xunta de Galicia | Ref. ED431C 2021/44Xunta de Galicia | Ref. ED481A-2021/337Ministerio de Ciencia e Innovación, Xunta de Galicia con fondos de la Unión Europea NextGenerationEU y el Fondo Europeo Marítimo y de Pesca | Ref. PRTR-C17.I