Adaptive mesh simulations of compressible flows using stabilized formulations

This thesis investigates numerical methods that approximate the solution of compressible flow equations. The first part of the thesis is committed to studying the Variational Multi-Scale (VMS) finite element approximation of several compressible flow equations. In particular, the one-dimensional Burgers equation in the Fourier space, and the compressible Navier-Stokes equations written in both conservative and primitive variables are considered. The approximations made for the VMS formulation are extensively researched; the design of the matrix of stabilization parameters, the definition of the space where the subscales live, the inclusion of the temporal derivatives of the subscales, and the non-linear tracking of the subscales are formulated. Also, the addition of local artificial diffusion in the form of shock capturing techniques is included. The accuracy of the formulations is studied for several regimes of the compressible flow, from aeroacoustic flows at low Mach numbers to supersonic shocks. The second part of the thesis is devoted to make the solution of the smallest fluctuating scales of the compressible flow affordable. To this end, a novel algorithm for $h-$refinement of computational physics meshes in a distributed parallel setting, together with the solution of some refinement test cases in supercomputers are presented. The definition of an explicit a-posteriori error estimator that can be used in the adaptive mesh refinement simulations of compressible flows is also developed; the proposed methodology employs the variational subscales as a local error estimate that drives the mesh refinement. The numerical methods proposed in this thesis are capable to describe the high-frequency fluctuations of compressible flows, especially, the ones corresponding to complex aeroacoustic applications. Precisely, the direct simulation of the fricative [s] sound inside a realistic geometry of the human vocal tract is achieved at the end of the thesis.Esta tesis investiga métodos numéricos que aproximan la solución de las ecuaciones de flujo compresible. La primera parte de la tesis está dedicada al estudio de la aproximación numérica del flujo compresible por medio del método multiescala variacional (VMS) en elementos finitos. En particular, se consideran la ecuación de Burgers unidimensional descrita en el espacio de Fourier y las ecuaciones de Navier-Stokes de flujo compresible escritas en variables conservativas y primitivas. Las aproximaciones hechas para plantear la formulación VMS son ampliamente investigadas; el diseño de la matriz de parámetros de estabilización, la definición del espacio donde viven las subescalas, la inclusión de las derivadas temporales de las subescalas y el seguimiento no lineal de las subescalas son particularidades de la formulación que se analizan para cada una de las ecuaciones consideradas. Además, se incluye la adición de difusión artificial local en forma de técnicas de captura de choque. La precisión de las formulaciones se estudia para varios regímenes del flujo compresible, desde flujos aeroacústicos a bajos números de Mach hasta choques supersónicos. La segunda parte de la tesis está dedicada a hacer asequible la solución de las escalas fluctuantes más pequeñas del flujo compresible. Con este fin, se presenta un algoritmo novedoso para el refinamiento $h$ de las mallas de física computacional usadas en computación distribuida en paralelo. Además, se demuestra la solución en superordenadores de algunos casos de prueba del refinamiento de mallas. También se desarrolla la definición de un estimador de error explícito a posteriori que se puede usar en las simulaciones adaptativas de refinamiento de malla de flujos compresibles; la metodología propuesta emplea las subescalas variacionales como una estimación de error local que induce el refinamiento de la malla. Los métodos numéricos propuestos en esta tesis son capaces de describir las fluctuaciones de alta frecuencia de los flujos compresibles, especialmente los correspondientes a aplicaciones aeroacústicas complejas. Precisamente, la simulación directa del sonido consonántico fricativo [s] dentro de una geometría realista del tracto vocal humano se demuestra al final de la tesis

Refficientlib: an efficient load-rebalanced adaptive mesh refinement algorithm for high-performance computational physics meshes

In this paper we present a novel algorithm for adaptive mesh refinement in computational physics meshes in a distributed memory parallel setting. The proposed method is developed for nodally based parallel domain partitions where the nodes of the mesh belong to a single processor, whereas the elements can belong to multiple processors. Some of the main features of the algorithm presented in this paper are its capability of handling multiple types of elements in two and three dimensions (triangular, quadrilateral, tetrahedral, and hexahedral), the small amount of memory required per processor, and the parallel scalability up to thousands of processors. The presented algorithm is also capable of dealing with nonbalanced hierarchical refinement, where multirefinement level jumps are possible between neighbor elements. An algorithm for dealing with load rebalancing is also presented, which allows us to move the hierarchical data structure between processors so that load unbalancing is kept below an acceptable level at all times during the simulation. A particular feature of the proposed algorithm is that arbitrary renumbering algorithms can be used in the load rebalancing step, including both graph partitioning and space-filling renumbering algorithms. The presented algorithm is packed in the Fortran 2003 object oriented library \textttRefficientLib, whose interface calls which allow it to be used from any computational physics code are summarized. Finally, numerical experiments illustrating the performance and scalability of the algorithm are presented. No separate or additional fees are collected for access to or distribution of the wor

Refficientlib: an efficient load-rebalanced adaptive mesh refinement algorithm for high-performance computational physics meshes

No separate or additional fees are collected for access to or distribution of the work.In this paper we present a novel algorithm for adaptive mesh refinement in computational physics meshes in a distributed memory parallel setting. The proposed method is developed for nodally based parallel domain partitions where the nodes of the mesh belong to a single processor, whereas the elements can belong to multiple processors. Some of the main features of the algorithm presented in this paper are its capability of handling multiple types of elements in two and three dimensions (triangular, quadrilateral, tetrahedral, and hexahedral), the small amount of memory required per processor, and the parallel scalability up to thousands of processors. The presented algorithm is also capable of dealing with nonbalanced hierarchical refinement, where multirefinement level jumps are possible between neighbor elements. An algorithm for dealing with load rebalancing is also presented, which allows us to move the hierarchical data structure between processors so that load unbalancing is kept below an acceptable level at all times during the simulation. A particular feature of the proposed algorithm is that arbitrary renumbering algorithms can be used in the load rebalancing step, including both graph partitioning and space-filling renumbering algorithms. The presented algorithm is packed in the Fortran 2003 object oriented library \textttRefficientLib, whose interface calls which allow it to be used from any computational physics code are summarized. Finally, numerical experiments illustrating the performance and scalability of the algorithm are presented.Peer ReviewedPostprint (published version

El papel del sector transitario dentro del comercio exterior español

[ES] El presente trabajo de fin de grado pretende destacar el rol que tiene la empresa transitaria dentro del comercio internacional. Se pretende explicar las funciones y la importancia de este tipo de empresa desde el punto de vista del mercado exterior español. Hoy en día, la mayoría de productos que compramos no se han producido en España y provienen de mercados extranjeros. De la misma manera las empresas tienden a internacionalizarse para lograr ser más competitivas y conseguir recursos de otros países a menor coste. Gracias al fenómeno de la globalización , las mejoras de la infraestructura en el transporte y los avances tecnológicos, las cifras de comercio internacional se han disparado. Para entender la situación actual es preciso volver al pasado y observar cómo han evolucionado los intercambios internacionales de bienes entre países. Desde hace mucho tiempo que existe el comercio internacional, pero es a partir de la época de la colonización donde empieza a coger forma. Gracias a las políticas liberalizadoras de los países y a la integración económica de territorios se ha conseguido eliminar un gran número de barreras que complican las relaciones comerciales entre países. Cabe destacar que el desarrollo del internet ha sido clave para lograr una mayor rapidez en la comunicación y esto ha conllevado a que tanto el comercio internacional como el transporte y la logística avancen hacia la digitalización. Tras los conflictos internacionales provocados por la Primera y Segunda Guerra Mundial se han originado distintas organizaciones internacionales de carácter multilateral que tratan de resolver conflictos internacionales y lograr una mejor comunicación entre las naciones miembras con el fin de conseguir una mayor liberalización del mercado. España se encuentra dentro de las top 20 economías mundiales exportadoras e importadoras. Además los flujos comerciales de mercancías, a excepción de los años post crisis, han sufrido un constante crecimiento. Para entender esto es preciso resaltar la figura del transitario y sol rol de intermediación en las operaciones de comercio exterior que ha hecho posible que tanto grandes empresas como especialmente Pymes afronten su proceso de internacionalización comercial con mayor confianza. Las operaciones de exportación e importación son muy complejas y requieren de una elevada especialización. Las aduanas siguen siendo una gran barrera para el libre intercambio de mercancías. A pesar de que hoy en días tienen como prioridad la función de controlar y aportar mayor seguridad en los flujos de mercancías más que un carácter recaudatorio, sus gestiones son bastantes complejas y es necesario la figura de una agente de aduanas u Operador Económico Autorizado (OEA) que se encargue de la tramitación documental y el pago de impuestos. En la cadena de la logística internacional intervienen un gran número de agentes. El papel del transitario es clave en este aspecto, ya que conecta al exportador e importador con los demás partícipes. Además su experiencia en mercados internacionales y su gran red de contactos en el extranjero permiten ofrecer al cliente la manera más eficiente para llevar a cabo el transporte y la logística de la mercancía. Por último se hará una breve mención sobre las perspectivas de futuro del sector y los posibles cambios que se producirán en la industria. El trabajo quedará reforzado con una serie de conclusiones enfocadas en destacar la importancia del transitario en el comercio internacional.[EN] This final degree project aims to highlight the role of the freight forwarder in the international trade. It is intended to explain the functions and importance of this type of company from the point of view of the Spanish foreign market. Today, most of the products we buy have not been produced in Spain and come from foreign markets. In the same way, companies tend to internationalize to be more competitive and obtain resources from other countries at a lower cost. Thanks to the phenomenon of globalization, improvements in transport infrastructure and technological advances, international trade numbers have skyrocketed. To understand the current situation, it is necessary to return to the past and observe how international exchanges of goods between countries have evolved. International trade has been around for a long time, but it is from the time of colonization that it began to take shape. Thanks to the liberalizing policies of the countries and the economic integration of territories, a large number of barriers that complicate trade relations between countries have been eliminated. It should be noted that the development of the internet has been key in order to achieve a better communication and this has led to both international trade and transport and logistics move towards digitalization. After the international conflicts caused by the First and Second World War, different international organizations of a multilateral nature have been created to try to resolve international conflicts and achieve better communication between the member nations in order to achieve greater market liberalization. Spain is among the top 20 exporting and importing world economies. In addition, commercial merchandise flows, with the exception of the post-crisis years, have undergone constant growth. To understand this, it is necessary to highlight the figure of the freight forwarder and its intermediation role in foreign trade operations that has made it possible for both large companies and especially SMEs to face their commercial internationalization process with greater confidence. Export and import operations are very complex and require high specialization. Customs remain a great barrier to the free exchange of goods. Although today they have as a priority the function of controlling and providing greater security in the flow of goods rather than a tax collection, their efforts are quite complex and the figure of a customs agent or an Authorised Economic Operator (AEO) is required to manage all the documentary processing and the payment of taxes. A large number of agents are involved in the international logistics chain. The role of the freight forwarder is key in this regard, since it connects the exporter and importer with the other participants. In addition, their experience in international markets and their large network of contacts abroad allows to offer the customer the most efficient way to carry out the transport and logistics of the merchandise. Finally, a brief mention will be made about the future perspectives of the sector and the possible changes that will occur in the industry. The work will be reinforced with a series of conclusions focused on highlighting the importance of the freight forwarder in international trade.Bayona Barrios, CD. (2019). El papel del sector transitario dentro del comercio exterior español. http://hdl.handle.net/10251/128214TFG

Propuesta para la formulación de un mecanismo de gestión Nexo Agua-Energía en la industria de hidrocarburos en el Valle del Magdalena Medio

Se propone desarrollar un sistema nexo agua-energía para el manejo de las aguas de producción en el Valle Medio del Magdalena; para esto se hace una aproximación al estado actual del nexo, y se dan recomendaciones al respecto de aspectos importantes como información, tecnologías de tratamientos y manejo de agua, normatividad, actores implicados y las relaciones entre sectores, entre otros, que son necesarios para desarrollar una gestión con esta filosofía. Las aguas de producción de hidrocarburos hacen referencia al agua que se encuentra naturalmente con los hidrocarburos o aquella que es inyectada para mejorar la operación del campo, y que emerge a superficie con el gas o el crudo durante la explotación. Debido a su calidad es considerada un residuo. En Colombia su manejo final es principalmente la reinyección (70%) y el vertimiento en superficie (30%) aprox. La relación de producción agua-petróleo aceptada en Colombia es de 12:1. Para realizar el vertimiento en superficie es necesario efectuar un tratamiento previo, a fin de no generar afectaciones medioambientales al suelo o a otros cuerpos de agua. La normatividad de cada país normalmente se encarga de establecer las condiciones obligatorias para efectuar el vertimiento. Colombia cuenta con normas de vertimiento en cuerpos de agua, vertimiento en suelo, reúso, así como con numerosas herramientas de gestión del recurso hídrico y protección medio ambiental; más la efectividad y control de estas se pone en duda. El panorama en Colombia es el de falta generalizada de información sobre los recursos hídricos, en especial en aspectos de calidad del agua. De igual forma, el nexo agua-energía, se encuentra en un estado prácticamente nulo; para la muestra la reciente conflictividad entre sectores de elevado interés nacional como la generación hidroeléctrica y la explotación de hidrocarburos. Aspectos como información, confiabilidad, requerimientos técnicos para las operaciones y las oportunidades y retos son abordados en este trabajo.Abstract: It is proposed to develop a water-energy nexus system for the management of produced water in the Middle Valley of Magdalena, Colombia; This job is an approximation to the current state of the Nexus, and gives recommendations over aspects such as information, technologies, treatments and water management practices, regulations, stakeholders and relationships, necessaries to develop a management with this philosophy. The produced water of hydrocarbons is the water that is naturally found with the hydrocarbons, or this one that is injected to improve the operation of the field, and emerge to surface with gas or oil during the production activities. Normally, the quality of this water is poor and is considered a waste; in Colombia the final management is mainly reinjection (70%) and surface discharge (30%) approx. The actual water-oil ratio production accepted for Colombia is 12:1. It is necessary to treat these effluents before the discharge to avoid environmental affectations in soil and water bodies Normally each country has established own laws and norms to limit de emission of contaminations. Colombia counts with regulations about, discharge on water bodies, discharge on soil, reuse, as numerous tools for water management and environment protection. But the effectivity and control of these norms is in doubt. The concept of Nexus in resources management is becoming more common. Produced water have their own relation to energy; the aim is to use this approach as an alternative to achieve the effective implementation and control of management decision’s, for these waters in the Middle Magdalena Valley Colombia has a general lack of information about water resources, especially in water quality conditions. By other side, the water-energy nexus is in a practically null state. Is developed an approximation to necessary conditions for the implementation of nexus, as information, confiability, technical requirements, and opportunities and challenge.Maestrí

Variational multiscale error estimators for the adaptive mesh refinement of compressible flow simulations

This article investigates an explicit a-posteriori error estimator for the finite element approximation of the compressible Navier–Stokes equations. The proposed methodology employs the Variational Multi-Scale framework, and specifically, the idea is to use the variational subscales to estimate the error. These subscales are defined to be orthogonal to the finite element space, dynamic and non-linear, and both the subscales in the interior of the element and on the element boundaries are considered. Another particularity of the model is that we define some norms that lead to a dimensionally consistent measure of the compressible flow solution error inside each element; a scaled -norm, and the calculation of a physical entropy measure, are both studied in this work. The estimation of the error is used to drive the adaptive mesh refinement of several compressible flow simulations. Numerical results demonstrate good accuracy of the local error estimate and the ability to drive the adaptative mesh refinement to minimize the error through the computational domain.Peer ReviewedPostprint (author's final draft

Solution of low Mach number aeroacoustic flows using a Variational Multi-Scale finite element formulation of the compressible Navier–Stokes equations written in primitive variables

In this work we solve the compressible Navier–Stokes equations written in primitive variables in order to simulate low Mach number aeroacoustic flows. We develop a Variational Multi-Scale formulation to stabilize the finite element discretization by including the orthogonal, dynamic and non-linear subscales, together with an implicit scheme for advancing in time. Three additional features define the proposed numerical scheme: the splitting of the pressure and temperature variables into a relative and a reference part, the definition of the matrix of stabilization parameters in terms of a modified velocity that accounts for the local compressibility, and the approximation of the dynamic stabilization matrix for the time dependent subscales. We also include a weak imposition of implicit non-reflecting boundary conditions in order to overcome the challenges that arise in the aeroacoustic simulations at low compressibility regimes. The order of accuracy of the method is verified for two- and three-dimensional linear and quadratic elements using steady manufactured solutions. Several benchmark flow problems are studied, including transient examples and aeroacoustic applications.Peer ReviewedPostprint (author's final draft