Agent-supported simulation environment for intelligent manufacturing and warehouse management systems

Abstract

The main objective of this PhD thesis is the study of Diesel sprays under evaporative conditions by means of Large Eddy Simulations (LES) techniques. This study has been performed implementing a precise, low-demanding LES model in the free, full-purpose Computational Fluid Dynamics (CFD) code OpenFOAM.The starting point was a careful and exhaustive review of the physical processes involved in sprays. An emphasis in CFD methodology, particularly for LES methods, was essential for the thesis, as we were able to find the possible problems and limitations of our approximation. Moreover, as the most widely used techniques for the industrial simulation of sprays are based on the Reynolds-Averaged Navier-Stokes models, we have highlighted the many advantages of LES modeling. As the latter are, by definition, more computationally expensive than RANS, we made an optimal configuration that, while it is able to recover accurately the experimental results, its characteristic time is in the same order of magnitude that RANS ones. As applicability is a must in this thesis, we use the surname "Engineering" LES.One of the key points of the thesis has been the correct configuration of the flow turbulent conditions on the inlet. In order to get accurate results, the turbulent structures coming from this inlet need to be time-and spacecoherent. An adequate calibration of this conditions is needed to perform any spray simulation.Last but not least, all the simulations performed where validated against experiments, obtaining a very good agreement even close to the nozzle. vi ResumenEl objetivo principal de esta tesis es el estudio del modelado numérico de chorros diesel evaporativos mediante la técnica de la simulación de grandes remolinos (LES por sus siglas en inglés). Este estudio se ha realizado mediante la implementación de un modelo LES de altas prestaciones y poco consumo informático en el código libre de dinámica de fluidos computacional (CFD) OpenFOAM.El trabajo de esta tesis ha partido de una revisión exhaustiva de los procesos físicos que tienen lugar en el chorro desde la perspectiva del modelado CFD en general y LES en particular. Esta revisión nos ha permitido identificar los problemas y limitaciones de nuestro planteamiento. Además, dado que la principal técnica CFD usada para el modelado de chorro diesel en procesos industriales son los modelos basados en las ecuaciones promediadas de Reynolds (RANS), se ha incidido en la tesis sobre las ventajas del modelado LES. Dado que estas técnicas son inherentemente más caras que los métodos RANS, se ha hecho hincapié en conseguir una configuraciónóptima que, siendo lo más fiel posible a los resultados experimentales, esté cercana a los tiempos propios de las técnicas RANS. Entendiendo que se quiere hacerénfasis en la aplicabilidad del modelo, se habla de "Engineering" LES.Uno de los puntos claves de la tesis es la adecuada configuración de las condiciones de contorno turbulentas a la entrada de la tobera, que necesitan ser coherentes tanto en espacio como en tiempo. L...

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