Documents published in Scipedia

• A Parallel Solver for CFD based on the Alternating Anderson-Richardson Method

  L. Chan, S. Marques, N. Hills

  eccomas2022.

  
  

  Abstract

  Recent advancement in the usage and deployment of large supercomputing resources require the need for algorithmic improvements to make use of the increased parallelism architecture. The Alternating Anderson-Richardson (AAR) method has been recently shown to exhibit good performance when solving problems in distributed parallel computers. This research will extend and investigate the performance of the AAR method to solve CFD problems using a modern compressible flow solver. This work will compare its performance and scalability against commonly used linear solvers, such as the Richardson method and the Generalised Minimal RESidual (GMRES), for solving large, sparse linear systems of equations arising from CFD applications. Results using a range of turbomachinery test cases demonstrate that the current AAR implementation offers significant performance improvement over the Richardson method. The speedup of AAR with respect to GMRES is less significant due to the load imbalance across partitions.

  Abstract
  Recent advancement in the usage and deployment of large supercomputing resources require the need for algorithmic improvements to make use of the increased parallelism architecture. [...]

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• Next-generation HPC models for future Rotorcraft applications

  N. Sanguini, T. Benacchio, D. Malacrida, F. Cipolletta, F. Rondina, A. Sciarappa, L. Capone

  eccomas2022.

  
  

  Abstract

  Rotorcraft technologies pose great scientific and industrial challenges for numerical computing. As available computational resources approach the exascale, finer scales and therefore more accurate simulations of engineering test cases become accessible. However, shifting legacy workflows and optimizing parallel efficiency and scalability of existing software on new hardware is often demanding. This paper reports preliminary results in CFD and structural dynamics simulations using the T106A Low Pressure Turbine (LPT) blade geometry on Leonardo S.p.A.'s davinci-1 high-performance computing (HPC) facility. Time to solution and scalability are assessed for commercial packages Ansys Fluent, STAR-CCM+, and ABAQUS, and the open-source scientific computing framework PyFR. In direct numerical simulations of compressible fluid flow, normalized time to solution values obtained using PyFR are found to be up to 8 times smaller than those obtained using Fluent and STAR-CCM+. The findings extend to the incompressible case. All models offer weak and strong scaling in tests performed on up to 48 compute nodes, each with 4 Nvidia A100 GPUs. In linear elasticity simulations with ABAQUS, both the iterative solver and the direct solver provide speedup in preliminary scaling tests, with the iterative solver outperforming the direct solver in terms of time-to-solution and memory usage. The results provide a first indication of the potential of HPC architectures in scaling engineering applications towards certification by simulation, and the first step for the Company towards the use of cutting-edge HPC toolkits in the field of Rotorcraft technologies.

  Abstract
  Rotorcraft technologies pose great scientific and industrial challenges for numerical computing. As available computational resources approach the exascale, finer scales and [...]

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• Wind Turbine Control using Machine Learning techniques

  L. Schena

  eccomas2022.

  
  

  Abstract

  This article presents two model-free controllers for wind-turbine torque and pitch control. These controllers are based on reinforcement learning (RL) and Bayesian optimization (BO) and do not rely on any mathematical model of the wind-turbine dynamics, in contrast to classical approaches designed on linearized models. The model-free controllers were benchmarked against a proportional-integral-derivative (PID) regulator in a numerical environment using Blade Element Momentum theory for computing the aerodynamic torque and the blade loads. The results showed that the model-free approaches could increase power harvesting while reducing wind turbine loads.

  Abstract
  This article presents two model-free controllers for wind-turbine torque and pitch control. These controllers are based on reinforcement learning (RL) and Bayesian optimization [...]

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• Separation behaviour of small foreign objects in dry foods

  S. Takeda, M. Saeki

  eccomas2022.

  
  

  Abstract

  It is difficult to detect small foreign objects such as hair and soft plastics in dry foods. In our laboratory, an electrostatic separator of small foreign objects in dry foods was developed. The separator consists of a grounded inclined rotating drum, a cylindrical electrode fixed at the centre of the drum, and a suction device. The principle of the separation is based on the difference in the charge per unit mass of the dry food and foreign objects. Although it was found that it is possible to obtain a high purity and a high recovery rate of foods using this separator, the understanding of the separation mechanism is still limited. In this study, we numerically investigated the separation behaviours of foreign objects and dry foods in the inclined rotating drum. The behaviours of the foreign objects and dry foods were calculated, considering the electrostatic force. The electric field strength was calculated by the finite difference method. The effect of the inclination angle of the rotating drum on the trajectory of the particles to be separated was investigated. To examine the validity of the calculation method, the experimental result was compared with the calculated result.

  Abstract
  It is difficult to detect small foreign objects such as hair and soft plastics in dry foods. In our laboratory, an electrostatic separator of small foreign objects in dry [...]

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• Geomiso ISA: a hybrid software for isogeometric analysis with plate elements and advanced spline techniques

  P. Karakitsios, K. Gogos, K. Mprellas

  eccomas2022.

  
  

  Abstract

  In this paper, we propose the Geomiso ISA program (www.geomiso.com), a new hybrid software for applications on static isogeometric analysis with plate elements. It is based on the isogeometric analysis, the powerful generalization of the traditional finite element analysis, which, in combination with the plate theory, has attracted increasing attention in construction industry over the last decade, as it achieves efficient design-throughanalysis procedures and shows superior performance. This recently developed program is not just a plug-in, but a both on-premises and cloud-based software solution, applicable to thin (Kirchhoff-Love theory) and thick (Mindlin-Reissner theory) plates. It is used to simulate spline models of slabs and analyze their strength and behavior, while it has many features in common with both finite element software and design programs. This new software solution addresses the rising industrial need for seamless integration of computer-aided design and computer-aided analysis, while it appears to be more efficient to finite element software packages with major improvements, as it facilitates the geometry modeling within analysis, and achieves superior accuracy per degree-of-freedom with shortened computational cost. This is the first time ever such a both on-premises and cloud-based software package has been developed.

  Abstract
  In this paper, we propose the Geomiso ISA program (www.geomiso.com), a new hybrid software for applications on static isogeometric analysis with plate elements. It is based [...]

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• Isogeometric representations for digital twins subjected to dynamic excitations with GEOMISO DNL software

  P. Karakitsios, I. Prentzas, A. Leontaris

  eccomas2022.

  
  

  Abstract

  The new Geomiso DNL software is proposed to facilitate the use of isogeometric analysis for nonlinear inelastic dynamic applications. This hybrid software solution combines isogeometric analysis and 3D design with advanced spline techniques, such as NURBS and Tsplines. Its dual nature satisfies the rising industrial need for unification of the fields of computer-aided design (CAD) and computer-aided analysis (CAE), as it eliminates geometric errors by merging geometry design with mesh generation into a single procedure. This paper presents sample nonlinear applications in structural dynamics. Geomiso DNL is seen to handle these situations remarkably well, as the numerical examples exhibit significantly improved accuracy of the results, and reduced computational cost, when compared with finite element software packages. Geomiso DNL is not just a plug-in, but a both on-premises and cloud-based software, which enables engineers to simulate complex dynamic phenomena, whose impact on industrial products and structures in real-world environments can be more efficiently estimated. Taking advantage of the new horizons offered in the peak of the Industry 4.0 era, the physical twin feeds, via cloud technology, with real-time data its geometrically exact digital twin, while a dynamic analysis is performed and crucial results about structure safety and quality are obtained. It is argued that Geomiso DNL is a new, more efficient, alternative to FEA software. This is the first time ever such a cloud-based program has been developed.

  Abstract
  The new Geomiso DNL software is proposed to facilitate the use of isogeometric analysis for nonlinear inelastic dynamic applications. This hybrid software solution combines [...]

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• Physics-driven digital twin for laser powder bed fusion on GPUs

  S. Ferreira, B. Klein, A. Stork, D. Fellner

  eccomas2022.

  
  

  Abstract

  Metal Additive Manufacturing (AM) processes such as Laser Powder Bed Fusion (LPBF) suffer from part distortion due to the localized melting and resolidification of the metal powder, which introduces stresses and strains. Despite becoming more and more important as a manufacturing process, options for simulating the printing process to predict the distortions are limited, especially because existing solutions often require very long computation times. In this work, we present the results of an implementation of the inherent strain method on graphics processing units (GPUs) that exploits the massive parallelism of the many GPU cores to speed up the simulations considerably compared to CPU-based implementations.

  Abstract
  Metal Additive Manufacturing (AM) processes such as Laser Powder Bed Fusion (LPBF) suffer from part distortion due to the localized melting and resolidification of the metal [...]

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• Immersed boundaries in hypersonic flows with considerations about high-fidelity and massive parallelism

  F. Nauleau, T. Bridel-Bertomeu, F. Vivodtzev, H. Beaugendre

  eccomas2022.

  
  

  Abstract

  This paper inscribes itself in the ongoing doctoral work of the first author which aims at adapting the immersed boundary conditions (IBC) technique to three-dimensional (3D) large eddy simulations (LES) of viscous hypersonic flows around complex vehicles. The work relies on a pre-existing in-house IBC code, HYPERION (HYPERsonic vehicle design using Immersed bOuNdaries), originally developed in two dimensions (2D) as a proof of concept that it is possible to use IBC in the presence of strongly shocked flows [4]. As a first step towards the optimization of the 3D HYPERION, we discuss in this paper a novel MPI/Open MP hybrid rasterization algorithm allowing for the detection of immersed cells in record time even for very large problems. We then consider the least-square-based reconstruction algorithm from HYPERION [4]. It was shown in the original paper that the number of neighbors used in the reconstruction is directly related to the condition number of the least-square matrix and an optimum can be found when the condition number reaches an asymptote. In 3D configurations it is found that the number of neighbors has to be very high to ensure the proper conditioning of the least-square matrix. If the computation is distributed on several MPI processes (as is always the case in 3D for realistic return times), gathering the information from that many neighbors can cause obvious communication issues it amounts to covering large stencils with unrealistically large MPI halos. We therefore introduce an algorithm designed for a hybrid MPI/OpenMP environment based on migratable tasks and the consensus algorithm developed by [9] to remedy the former shortcoming. Finally, we discuss the premise of the implementation of LES capabilities in HYPERION. The last milestone of the main author's doctoral work is indeed to study the feasibility of embedding wall laws in the IBC modeling and reconstruction algorithm to try and counteract the low accuracy of the near-wall phenomena caused by the lack of body-fitted mesh.

  Abstract
  This paper inscribes itself in the ongoing doctoral work of the first author which aims at adapting the immersed boundary conditions (IBC) technique to three-dimensional (3D) [...]

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• Vulnerability assessment of cultural heritage structures

  M. Kioumarsi, V. Plevris, A. Shabani

  eccomas2022.

  
  

  Abstract

  Cultural heritage (CH) assets are the legacy of a society that are inherited from the past generations and can give us lessons for contemporary construction. Not only the formally recognized CH assets but also the non-CH structures and infrastructure, and the interconnection between them are crucial to be considered in a vulnerability assessment tool for the sustainable reconstruction of historic areas. Since most CH assets were not designed based on robust design codes to resist natural hazards such as earthquakes, vulnerability assessment and preservation are pivotal tasks for the authorities. For this aim, Hyperion, an H2020 project (Grant agreement No 821054), was formed in order to take advantage of existing tools and services together with novel technologies to deliver an integrated vulnerability assessment platform for improving the resiliency of historic areas. Geometric documentation is the first and most important step toward the generation of digital twins of CH assets that can be facilitated using 3D laser scanners or drone imaging. Afterward, the finite element method is an accurate approach for developing the simulation-based digital twins of cultural heritage assets. For calibration of the models, the result of the operational modal analysis from the ambient vibration testing using accelerometers can be utilized. Structural analysis for the prediction of the structural behavior or near real-time analysis can be carried out on the calibrated models. However, the full finite element analysis needs a lot of computational effort, and to tackle this limitation, equivalent frame methods can be utilized.

  Abstract
  Cultural heritage (CH) assets are the legacy of a society that are inherited from the past generations and can give us lessons for contemporary construction. Not only the [...]

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• Digitization Principles for Application Scenarios towards Digital Twins of Organizations

  A. Sumereder, R. Woitsch

  eccomas2022.

  
  

  Abstract

  In today's agile business ecosystems, digital twins (DTs) and especially digital twins of organizations (DTOs) allow for adaption through dynamically evolving models depicting organizational aspects such as production processes, data flows, human actors and interactions. A hybrid modelling approach is utilized, as the establishment of such DTOs either considered on their own or as part of a DT ecosystem is not trivial. Meta modelling and meta model merging patterns are applied to integrate heterogeneous perspectives and domain models. Two main research questions with respect to digitization towards digital twinning are discussed: First, which digitization principles/patterns are appropriate for DTOs? Patterns ranging from 'counting' to 'estimation' are introduced to fill digital models serving as a foundation for DTs with data. As a starting point, potential digitization principles for relevant characteristics of BPMN ­ 'Modelling Method for Business Processes' and KPI ­ 'Modelling Method for Key Performance Indicators' models are considered. Second, which principle/pattern is appropriate for which organizational structure? In order to ease the selection of suitable patterns for specific application scenarios, those will be associated with organizational structures like but not limited to construction processes, assembly processes or production processes each of them with domain-specific characteristics. A prototype consisting of three phases ­ use case requirements collection, model design and digitization assistance ­ builds upon (a) physical experimentations in the OMiLAB Innovation Corner using physical assets such as edge devices or sensors, (b) domain specific services considering software related aspects such as timeseries databases or simulation algorithms, and (c) modelling methods enabling the integration of physical and digital components. The paint production pilot from the European Change2Twin project serves as an application scenario evaluation use case. A notion of what the use case company intends to achieve by digital twinning and what is possible by introducing digital services is touched. The outlook presents how artificial intelligence may be introduced for the prototype to leverage the paint production use case and further application scenarios.

  Abstract
  In today's agile business ecosystems, digital twins (DTs) and especially digital twins of organizations (DTOs) allow for adaption through dynamically evolving models depicting [...]

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