Study for the computational resolution of conservation equations of mass, momentum and energy

The main purpose of this project is the creation of a CFD program able to solve the Navier-Stokes equations. Before the realisation of this program, other programs solving different problems will be created, like a 2D heat conduction program, a potential flow program and a convection-diffusion program. After those are done and validated, the Navier-Stokes solving program will be done. This program must also be validated, so the results obtained are reliable

Numerical study of fluidic oscillators with compressible flow

Se estudiará el fllujo en el interior de osciladores fluídicos mediante el uso de un código abierto de Mecánica de Fluidos Computacional, prestando especial atención al comportamiento con flujo compresible.1. Documentación y estudio del estado del arte. 2. Aprendizaje de los conceptos básicos de la Mecánica de Fluidos Computacional. 3. Aprendizaje del software OpenFOAM. 4. Mallado del oscilador fluídico de referencia. 5. Lanzamiento de las simulaciones. 7. Extracción y análisis de resultados, comparándolos con los resultados obtenidos en simulaciones con flujo incompresible. 8. Conclusiones

Synthetic presentation of iterative asynchronous parallel algorithms.

Iterative asynchronous parallel methods are nowadays gaining renewed interest in the community of researchers interested in High Performance Computing (HPC), in the specific case of massive parallelism. This is because these methods avoid the deadlock phenomena and that moreover a rigorous load balancing is not necessary, which is not the case with synchronous methods. Such iterative asynchronous parallel methods are of great interest when there are many synchronizations between processors, which in the case of iterative methods is the case when convergence is slow. Indeed in iterative synchronous parallel methods, to respect the task sequence graph that defines in fact the logic of the algorithm used, processors must wait for the results they need and calculated by other processors; such expectations of the results emitted by concurrent processors therefore cause idle times for standby processors. It is to overcome this drawback that asynchronous parallel iterative methods have been introduced first for the resolution of large scale linear systems and then for the resolution of highly nonlinear algebraic systems of large size as well, where the solution may be subject to constraints. This kind of method has been widely studied worldwide by many authors. The purpose of this presentation is to present as broadly and pedagogically as possible the asynchronous parallel iterative methods as well as the issues related to their implementation and application in solving many problems arising from High Performance Computing. We will therefore try as much as possible to present the underlying concepts that allow a good understanding of these methods by avoiding as much as possible an overly rigorous mathematical formalism; references to the main pioneering work will also be made. After a general introduction we will present the basic concepts that allow to model asynchronous parallel iterative methods including as a particular case synchronous methods. We will then present the algorithmic extensions of these methods consisting of asynchronous sub-domain methods, asynchronous multisplitting methods as well as asynchronous parallel methods with flexible communications. In each case an analysis of the behavior of these methods will be presented. Note that the first kind of analysis allows to obtain an estimate of the asymptotic rate of convergence. The difficult problem of the stopping test of asynchronous parallel iterations will be also studied, both by computer sciences considerations and also by numerical aspects related to the mathematical analysis of the behavior of theses iterative parallel methods. The parallel asynchronous methods have been implemented on various architectures and we will present the main principles that made it possible to code them. These parallel asynchronous methods have been used for the resolution of several kind of mathematical problems and we will list the main applications processed. Finally we will try to specify in which cases and on which type of architecture these methods are efficient and interesting to use

METFAC-2.1 User's Guide

Technical ReportPostprint (author’s final draft

Development of Computational Fluid Dynamic codes for the numerical resolution of the Navier-Stokes equations applied to benchmark problems using finite volume method

Aprofundir en la simulació de les equacions fonamentals de la dinàmica de fluids i transferència de calor i massa, així com la seva aplicació en algun cas d’interès per l’estudiant en el camp de l’enginyeria industrial i/o aeronàutica.   Depenen del background de l’estudiant en la resolució multidimensional de les equacions de Navier-Stokes treballat en assignatures del seu màster, es farà una tutela personalitzada que li permeti avançar en la modelitzacióó de situacions més complexes d’acord amb els seus interessos.   Així, l’estudiant podrà aprofundir en el desenvolupament de codis de simulació de fluxos laminars en geometries complexes (malles no estructurades), fluxos turbulents (simulació directe de la turbulència i models de Large Eddy Simulation), fluxos bifàsics (sòlid-líquid o líquid-vapor), medis participants a la radiació, combustió, interacció sòlid-fluid, etc. El codis es desenvoluparan utilitzant preferentment tècniques de volums finits i en llenguatge de programació C o C++. També es considerarà la possibilitat de crear subrutines per ser implementades en codis de propòsit general (e.g. el codi obert OpemFoam, el codi TermoFluids, etc.).   L’estudiant tindrà també la possibilitat d’orientar el seu TFM a aplicacions específiques en el camp de l’optimització de sistemes i equips termo-fluídics i aeronàutics per tal d’aconseguir la seva optimització, i.e. màxima eficiència energètica amb el mínim cost i impacte ambiental. Aquí l’estudiant podrà proposar, d’acord amb els professors, aquelles situacions que consideri més adients als seus interessos. Com a possibles casos d’aplicació citarem:   En base al treball de simulació desenvolupat, una segona part del TFG estarà dirigida a aplicacions específiques en el camp de l’optimització de sistemes i equips termo-fluídics i aeronàutics per tal d’aconseguir la seva optimització, i.e. màxima eficiència energètica amb el mínim cost i impacte ambiental. Aquí l’estudiant podrà proposar, d’acord amb els professors, aquelles situacions que consideri més adients als seus interessos. Com a possibles casos d’aplicació citarem:   Advanced study for the computational resolution of conservation equations of mass, momentum and energy. Application to aerodynamics of airfoils shaped bodies.Advanced study for the computational resolution of conservation equations of mass, momentum and energy. Application to heating, ventilating, air conditioning and refrigeration (HVAC & R). Advanced study for the computational resolution of conservation equations of mass, momentum and energy. Application to combustion processes for aeronautic and aerospace applications. Advanced study for the computational resolution of conservation equations of mass, momentum and energy. Application to turbomachinery. Advanced study for the computational resolution of conservation equations of mass, momentum and energy. Application to solar thermal collectors for low and middle temperatures. Advanced study for the computational resolution of conservation equations of mass, momentum and energy. Application to thermal energy storage in industrial applications. Advanced study for the computational resolution of conservation equations of mass, momentum and energy. Application to analysis of the power block in thermoelectric plants. Advanced study for the computational resolution of conservation equations of mass, momentum and energy. Application to compact heat exchangers using micro-channels and fin-and-tube systems. Advanced study for the computational resolution of conservation equations of mass, momentum and energy. Application to bioengineering applications. Advanced study for the computational resolution of conservation equations of mass, momentum and energy. Application to refrigeration of electric and electronic components. Advanced study for the computational resolution of conservation equations of mass, momentum and energy. Application to solid-fluid interaction.  El títol final del TFM dependrà de l’aplicació final escollida. El llistat anterior és representatiu de com podria quedar el títol final.The main objective of this work is the development of different programs to learn and verify computational fluid dynamics problems which are governed by the Navier-Stokes equations. The document will be divided into different chapters in which we will detail the procedures performed. During the first chapter there will be an introduction on computational fluid dynamics problems, as the basic requirements to deal with this type of cases, as well as the limits that will be encountered during the development of these. In the second chapter there will be a brief introduction about the necessary theory which will be of great help during the development of the case studies. The convection-diffusion equations will be studied in the third chapter, which will be discretized for the development of the different cases. In this chapter we will also introduce the concept of Finite volume method that will be a fundamental part of this work. Finally, we will see the different numerical schemes that can be implemented, as well as the different solvers. During the fourth chapter the different cases will be presented, such as the Transient Conduction problem, the Diagonal flow and the Smith Hutton problem, which will be developed and commented. In the fifth chapter we will introduce in the Fractional Step Method, we will see the different steps to follow for the implementation of this method in the development of the case the Driven Cavity. the spatial discretization and the algorithm necessary for the development of this will be detailed. Finally, the results will be discussed, and the pertinent conclusions will be given. We will make an introduction to the field of turbulence that is why in chapter six the Burgers equations will be discretized; two different methods will be studied LES (Large eddy simulation) and DNS (Direct numerical simulation). The results obtained will be compared with the references given by the CTTC

Parallel alogorithms for MIMD parallel computers

This thesis mainly covers the design and analysis of asynchronous parallel algorithms that can be run on MIMD (Multiple Instruction Multiple Data) parallel computers, in particular the NEPTUNE system at Loughborough University. Initially the fundamentals of parallel computer architectures are introduced with different parallel architectures being described and compared. The principles of parallel programming and the design of parallel algorithms are also outlined. Also the main characteristics of the 4 processor MIMD NEPTUNE system are presented, and performance indicators, i.e. the speed-up and the efficiency factors are defined for the measurement of parallelism in a given system. Both numerical and non-numerical algorithms are covered in the thesis. In the numerical solution of partial differential equations, a new parallel 9-point block iterative method is developed. Here, the organization of the blocks is done in such a way that each process contains its own group of 9 points on the network, therefore, they can be run in parallel. The parallel implementation of both 9-point and 4- point block iterative methods were programmed using natural and redblack ordering with synchronous and asynchronous approaches. The results obtained for these different implementations were compared and analysed. Next the parallel version of the A.G.E. (Alternating Group Explicit) method is developed in which the explicit nature of the difference equation is revealed and exploited when applied to derive the solution of both linear and non-linear 2-point boundary value problems. Two strategies have been used in the implementation of the parallel A.G.E. method using the synchronous and asynchronous approaches. The results from these implementations were compared. Also for comparison reasons the results obtained from the parallel A.G.E. were compared with the ~ corresponding results obtained from the parallel versions of the Jacobi, Gauss-Seidel and S.O.R. methods. Finally, a computational complexity analysis of the parallel A.G.E. algorithms is included. In the area of non-numeric algorithms, the problems of sorting and searching were studied. The sorting methods which were investigated was the shell and the digit sort methods. with each method different parallel strategies and approaches were used and compared to find the best results which can be obtained on the parallel machine. In the searching methods, the sequential search algorithm in an unordered table and the binary search algorithms were investigated and implemented in parallel with a presentation of the results. Finally, a complexity analysis of these methods is presented. The thesis concludes with a chapter summarizing the main results