COLLECTIONS

Documents published in Scipedia

• Monte Carlo-Based and Sampling-Based Methods and Their Range of Applicability

  R. Schmidt, M. Voigt, M. Pisaroni, F. Nobile, P. Leyland, J. Prats, G. Bugeda

  (2018). Hirsch C., Wunsch D., Szumbarski J., Łaniewski-Wołłk Ł., Pons-Prats J. (eds) Uncertainty Management for Robust Industrial Design in Aeronautics. Notes on Numerical Fluid Mechanics and Multidisciplinary Design, vol 140. Springer, Cham

  
  

  Abstract

  The present section will focus on the applicability issues of Monte Carlo-based methods, as well as those methods based on sampling techniques. Special focus will be put on the Multi-Level Monte Carlo method and the two implementations developed during the UMRIDA project, namely the Continuous MLMC and MLMC. All named methods have been described in the above sections of this book.

  Abstract
  The present section will focus on the applicability issues of Monte Carlo-based methods, as well as those methods based on sampling techniques. Special focus will be put on [...]

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• Summary of UMRIDA Best Practices

  J. Pons Prats, G. Bugeda

  (2018). Hirsch C., Wunsch D., Szumbarski J., Łaniewski-Wołłk Ł., Pons-Prats J. (eds) Uncertainty Management for Robust Industrial Design in Aeronautics. Notes on Numerical Fluid Mechanics and Multidisciplinary Design, vol 140. Springer, Cham

  
  

  Abstract

  Uncertainty quantification (UQ) is becoming a strategic step in the design phase. Robust Design Optimization (RDO) is the following step. The Technological Readiness Level (TRL) of intrusive and non-intrusive methodologies is increasing rapidly, although several limitations remain. Nowadays, UQ is a major trend in research, because there is a lot of room for improvement.

  Abstract
  Uncertainty quantification (UQ) is becoming a strategic step in the design phase. Robust Design Optimization (RDO) is the following step. The Technological Readiness Level [...]

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• General Introduction to Monte Carlo and Multi-level Monte Carlo Methods

  R. Schmidt, M. Voigt, M. Pisaroni, F. Nobile, P. Leyland, J. Pons Prats, G. Bugeda

  (2019). Hirsch C., Wunsch D., Szumbarski J., Łaniewski-Wołłk Ł., Pons-Prats J. (eds) Uncertainty Management for Robust Industrial Design in Aeronautics. Notes on Numerical Fluid Mechanics and Multidisciplinary Design, vol 140. Springer, Cham

  
  

  Abstract

  In this chapter, we present a general introduction to Monte Carlo (MC)-based methods, sampling methodologies, stratification methods, and variance reduction techniques. In the first part, we will discuss the theoretical basis and the convergence proprieties of MC methods. The next part is devoted to pseudorandom and quasi-random number generation, the generation of random variables and the application of stratification. It is followed by techniques for correlation and discrepancy control. The third part presents the concept of Latin Hypercube Sampling (LHS). The last part introduces the concept of Multi-Level Monte Carlo (MLMC).

  Abstract
  In this chapter, we present a general introduction to Monte Carlo (MC)-based methods, sampling methodologies, stratification methods, and variance reduction techniques. In [...]

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• Multi-level Monte Carlo Method

  J. Pons Prats, G. Bugeda

  (2019). Hirsch C., Wunsch D., Szumbarski J., Łaniewski-Wołłk Ł., Pons-Prats J. (eds) Uncertainty Management for Robust Industrial Design in Aeronautics. Notes on Numerical Fluid Mechanics and Multidisciplinary Design, vol 140. Springer, Cham

  
  

  Abstract
  Uncertainty quantification has gained interest during the recent years. Two clear examples are NODESIM-CFD and, the just finished, UMRIDA projects.

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• Industrial application of genetic algorithms to cost reduction of a wind turbine equipped with a tuned mass damper

  J. Pons Prats, M. Coma, J. Betran, X. Roca, G. Bugeda

  (2018). Andrés-Pérez E., González L., Periaux J., Gauger N., Quagliarella D., Giannakoglou K. (eds) Evolutionary and Deterministic Methods for Design Optimization and Control With Applications to Industrial and Societal Problems. Computational Methods in Applied Sciences, vol 49. Springer, Cham

  
  

  Abstract

  Design optimization has already become an important tool in industry. The benefits are clear, but several drawbacks are still present, being the main one the computational cost. The numerical simulation involved in the solution of each evaluation is usually costly, but time and computational resources are limited. Time is key in industry. The present communication focuses on the methodology applied to optimize the installation and design of a Tuned Mass Damper. It is a structural device installed within the tower of a wind turbine aimed to stabilize the oscillations and reduce the tensions and the fatigue loads. The paper describes the decision process to define the optimization problem, as well as the issues and solutions applied to deal with a huge computational cost.

  Abstract
  Design optimization has already become an important tool in industry. The benefits are clear, but several drawbacks are still present, being the main one the computational [...]

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• Description of the Test Cases

  G. Bugeda, J. Periaux, N. Qin, J. Pons Prats

  (2020). Qin N., Periaux J., Bugeda G. (eds) Advances in Effective Flow Separation Control for Aircraft Drag Reduction. Computational Methods in Applied Sciences, vol 52. Springer, Cham

  
  

  Abstract

  The high-level objective of MARS project was to understand the formation and behaviour of turbulent structures which affects the Reynolds stress and skin friction. The aim was, once understood, to apply flow control techniques in order to control these structures and reduce the overall drag derived from the Reynolds stress and mainly from the skin friction. Active flow control devices were the main interest; DBD plasma, Synthetic jets, Micro Blowing and Suction, Moving Surfaces were included on the list. To test all these devices, two test cases were defined, and a database and file repository were established in the project webserver. The present chapter is aimed to describe the test cases, including the set-up of the flow control devices, as well as to describe the file repository were all the data was stored.

  Abstract
  The high-level objective of MARS project was to understand the formation and behaviour of turbulent structures which affects the Reynolds stress and skin friction. The aim [...]

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• Optimization of the Experimental Set-up for a Turbulent Separated Shear Flow Control by Plasma Actuator Using Genetic Algorithms

  N. Benard, J. Pons Prats, J. Periaux, J. Bonnet, G. Bugeda

  (2020). Qin N., Periaux J., Bugeda G. (eds) Advances in Effective Flow Separation Control for Aircraft Drag Reduction. Computational Methods in Applied Sciences, vol 52. Springer, Cham

  
  

  Abstract

  Since 1947, when Schubauer and Skramstad established the basis of the technology with its revolutionary work about steady state tools and mechanisms for the flow management, the progress of the flow control technology and the development of devices have progressed constantly. Anyway, the applicability of such devices is limited, and only few of them have arrived to the assembly workshop. The problem is that the range of actuation is still limited. Despite their operability limitations, flow control devices are of great interest for the aeronautical industry. The number of projects investigating this technology demonstrates the relevance of in the Fluid Dynamic field. The scientific interest focus not only on the industrial applications and the improvement of the technology, but also on the deep understanding of the physical phenomena associated to the flow separation, turbulence formation associated to the final drag reduction aim. A clear example of what has been mentioned is the EC MARS research project (MARS project, FP7 project number 266326, [2]). Its objectives are aimed to a better understanding of the Reynolds Stress and turbulent flow related to both drag reduction and flow control. The research was carried out through the analysis of several flow control devices and the optimization of the parameters for some of them was an important element of the research. When solving a traditional fluid dynamics optimisation problem numerical flow analysis are used instead of experimental ones due to their lower cost and shorter needed time for evaluation of candidate solutions. Nevertheless, in the particular case of the selected flow control plasma devices the experimental measurement of the performance of each candidate configuration has been much quicker than a numerical analysis. For this reason, the corresponding optimisation problem has been solved by coupling an evolutionary optimization algorithm with an experimental device. This paper discusses the design quality and efficiency gained by this innovative coupling.

  Abstract
  Since 1947, when Schubauer and Skramstad established the basis of the technology with its revolutionary work about steady state tools and mechanisms for the flow management, [...]

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• Drag reduction via turbulent boundary layer flow control

  A. Abbas, G. Bugeda, E. Ferrer, S. Fu, J. Periaux, J. Pons Prats, E. Valero, Y. Zheng

  Science China-Technological Sciences (2017). Vol. 60 (9), pp. 1281-1290 (Preprint)

  
  

  Abstract

  Turbulent boundary layer control (TBLC) for skin-friction drag reduction is a relatively new technology made possible through the advances in computational-simulation capabilities, which have improved the understanding of the flow structures of turbulence. Advances in micro-electronic technology have enabled the fabrication of active device systems able to manipulating these structures. The combination of simulation, understanding and micro-actuation technologies offers new opportunities to significantly decrease drag, and by doing so, to increase fuel efficiency of future aircraft. The literature review that follows shows that the application of active control turbulent skin-friction drag reduction is considered of prime importance by industry, even though it is still at a low technology readiness level (TRL). This review presents the state of the art of different technologies oriented to the active and passive control for turbulent skin-friction drag reduction and contributes to the improvement of these technologies.

  Abstract
  Turbulent boundary layer control (TBLC) for skin-friction drag reduction is a relatively new technology made possible through the advances in computational-simulation capabilities, [...]

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• Turbulent separated shear flow control by surface plasma actuator: experimental optimization by genetic algorithm approach

  N. Benard, J. Pons Prats, J. Periaux, G. Bugeda, P. Braud, J. Bonnet, E. Moreau

  Experiments in Fluids (2016). (preprint) Vol. 57 (2), pp. 1-17

  
  

  Abstract

  The potential benefits of active flow control are no more debated. Among many others applications, flow control provides an effective mean for manipulating turbulent separated flows. Here, a nonthermal surface plasma discharge (dielectric barrier discharge) is installed at the step corner of a backward-facing step (U 0 = 15 m/s, Re h  = 30,000, Re θ  = 1650). Wall pressure sensors are used to estimate the reattaching location downstream of the step (objective function #1) and also to measure the wall pressure fluctuation coefficients (objective function #2). An autonomous multi-variable optimization by genetic algorithm is implemented in an experiment for optimizing simultaneously the voltage amplitude, the burst frequency and the duty cycle of the high-voltage signal producing the surface plasma discharge. The single-objective optimization problems concern alternatively the minimization of the objective function #1 and the maximization of the objective function #2. The present paper demonstrates that when coupled with the plasma actuator and the wall pressure sensors, the genetic algorithm can find the optimum forcing conditions in only a few generations. At the end of the iterative search process, the minimum reattaching position is achieved by forcing the flow at the shear layer mode where a large spreading rate is obtained by increasing the periodicity of the vortex street and by enhancing the vortex pairing process. The objective function #2 is maximized for an actuation at half the shear layer mode. In this specific forcing mode, time-resolved PIV shows that the vortex pairing is reduced and that the strong fluctuations of the wall pressure coefficients result from the periodic passages of flow structures whose size corresponds to the height of the step model.

  Abstract
  The potential benefits of active flow control are no more debated. Among many others applications, flow control provides an effective mean for manipulating turbulent separated [...]

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• Docencia e investigación: ¿un falso dilema?

  E. Montilla, G. Amblàs, G. Bugeda, S. Roca

  Aula abierta (2013). Vol. 41 (2), pp. 13-22

  
  

  Abstract

  La Universidad Politécnica de Cataluña (UPC) dispone de un modelo de evaluación docente plenamente consolidado, que está adaptado a los requerimientos que emanan de la implantación del Espacio Europeo de Educación Superior. Dicho modelo de evaluación ha sido homologado por la Agència per a la Qualitat del Sistema Universitari de Catalunya (AQU Catalunya), la agencia de evaluación catalana y se basa en las directrices europeas más exigentes. Este modelo se ha empleado para evaluar la docencia del profesorado en seis convocatorias, por lo que se dispone de una información exhaustiva, tanto a nivel agregado como separado por colectivos y ámbitos de conocimiento. Por otro lado, también se dispone de información sobre la actividad investigadora del profesorado, medida mediante el número de sexenios obtenidos. En este artículo se presentan estos datos y se estudia si existe una correlación positiva entre la calidad de la docencia impartida y el reconocimiento de las tareas investigadoras de los profesores, medida a través del número de sexenios obtenidos. Nuestros resultados indican que tal correlación existe, aunque es más débil de lo que cabría esperar.

  Abstract
  La Universidad Politécnica de Cataluña (UPC) dispone de un modelo de evaluación docente plenamente consolidado, que está adaptado a los requerimientos [...]

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