Aprèn - Antonio Huerta

El Three-Sphere micro-swimmer és un swimmer artificial a micro-escala, amb potencials aplicacions en la biomedicina, que consisteix en tres esferes unides per dos braços rígids les longituds dels quals varien entre dos valors. El comportament físic d'aquest dispositiu en un fluid està modelat pel flow de Stokes en règims de nombre de Reynolds petit, on les forces de viscositat dominen la dinàmica enfront de la inèrcia. Aquest swimmer és simulat tant en un domini infinit de tres dimensions com en un cilindre confinat, sent aquest últim el principal cas d'estudi. En aquest treball es presenta la modelització matemàtica del micro-swimmer com un conjunt de sistemes d'equacions diferencials parcials (EDP) que se solucionen numèricament amb el mètode de Face Centered Finite Volumes (FCFV) i generant les malles amb el software Gmsh. L'objectiu d'aquest treball és calcular els camps de velocitat i pressió de l'equació de Stokes així com les forces d'arrossegament exercides pel fluid sobre cada esfera en algunes configuracions geomètriques del model per analitzar qualitativament i numèricament la dinàmica del “swimmer”. Posteriorment, es presenta un estudi numèric per avaluar la qualitat de les solucions obtingudes mitjançant mètodes d'alt ordre.

El “Three-Sphere micro-swimmer” es un “swimmer” artificial a micro-escala, con potenciales aplicaciones en la biomedicina, que consiste en tres esferas unidas por dos brazos rígidos cuyas longitudes varían entre dos valores. El comportamiento físico de este dispositivo en un fluido está modelado por el ”flow de Stokes” en regímenes de número de Reynolds pequeño, donde las fuerzas de viscosidad dominan la dinámica frente a la inercia. Este “swimmer” es simulado tanto en un dominio infinito de tres dimensiones como en un cilindro confinado, siento este último el principal caso de estudio. En este trabajo se presenta la modelización matemática del “micro-swimmer” como un conjunto de sistemas de ecuaciones diferenciales parciales (EDP) que se solucionan numéricamente con el método “Face Centered Finite Volumes” (FCFV) y generando las mallas con el software Gmsh. El objetivo de este trabajo es calcular los campos de velocidad y presión de la ecuación de Stokes así como las fuerzas de arrastre ejercidas por el fluido sobre cada esfera para algunas configuraciones geométricas del modelo para analizar cualitativamente y numéricamente la dinámica del “swimmer”. Posteriormente, se presenta un estudio numérico para evaluar la calidad de las soluciones obtenidas usando métodos de alto orden.

The Three-Sphere micro-swimmer is an artificial swimmer at the micro-scale, with potential applications in bio-medicine, which consists of three spheres linked by rigid rods whose lengths vary between two values. The physical behavior of this device in a fluid is modeled by the Stokes flow at low-Reynolds number regimes, where viscous forces dominate over inertia. This swimmer is simulated both for an infinite three-dimensional domain and a confined capillary tube, being the latter the main case of study. In this work, the mathematical modeling of the micro-swimmer is stated as a set of PDE problems whose solution is tackled numerically with the Face Centered Finite Volume (FCFV) method and its computational meshes generated with Gmsh software. The aim of this work is to compute the velocity and pressure fields from the Stokes equations as well as the drag applied by the fluid over each of the spheres for some geometrical configurations, leading to a qualitative and numerical analysis of its locomotion. Afterwards, a numerical study to assess the quality of the solutions will be made using High Order methods.

Development of numerical tools for modelling electrical streamers

Master thesis

Candela Rubio, Héctor

Tutor / Supervisor: Montañá Puig, Juan; Huerta, Antonio

Publication date: 2023

Terrassa School of Industrial, Aerospace and Audiovisual Engineering (ESEIAAT)

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Topology optimization in OpenFOAM using a continuous adjoint framework

Master thesis

Kever, Nadeem

Tutor / Supervisor: Giacomini, Matteo; Huerta, Antonio

Publication date: 2023

Barcelona School of Civil Engineering (ETSECCPB)

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En aquest treball informem sobre l'addició de funcions a un solucionador d'optimització de topologia OpenFOAM existent. Comencem amb un resum detallat de les bases teòriques de l'optimització de la topologia en el cas de les equacions de Navier-Stokes en estat estacionari incompressibles sota un marc adjunt. A continuació, descriurem les bases teòriques per a la implementació del nostre solucionador estès. És a dir, hem implementat dues funcions noves: una funció objectiu de dissipació de potència i una restricció de volum. La validesa de la restricció de volum es prova amb èxit mitjançant un problema de joguina. Després de la validació, les sortides del solucionador recentment modificat es comparen amb la literatura per als casos que inclouen un sistema de conductes amb una entrada i dues sortides, una configuració alternativa del mateix sistema de conductes i un problema de doble coll d'ampolla de dues sortides. També incloem una revisió de la literatura actual sobre mètodes d'optimització de topologia i la implementació de restriccions de volum en mètodes basats en la densitat. See original in english in case of inaccurate translation.

En este trabajo informamos sobre la adición de funciones a un solucionador de optimización de topología OpenFOAM existente. Comenzamos con un resumen detallado de la base teórica de la optimización topológica en el caso de las ecuaciones de Navier-Stokes de estado estacionario incompresible bajo un marco adjunto. Luego describimos la base teórica para la implementación de nuestro solucionador extendido. A saber, hemos implementado dos nuevas funciones: una función objetivo de disipación de potencia y una restricción de volumen. La validez de la restricción de volumen se prueba con éxito a través de un problema de juguete. Después de la validación, las salidas del solucionador recién modificado se comparan con la literatura para casos que incluyen un sistema de conductos con una entrada y dos salidas, una configuración alternativa del mismo sistema de conductos y un problema de cuello de botella doble y dos salidas. También incluimos una revisión de la literatura actual sobre métodos de optimización de topología y la implementación de restricciones de volumen en métodos basados en densidad. See original in english in case of inaccurate translation.

In this work we report on the addition of features to an existing OpenFOAM topology optimization solver. We begin with a detailed summary of the theoretical basis of topology optimization in the case of the incompressible steady-state Navier-Stokes equations under an adjoint framework. We then describe the theoretical basis for the implementation of our extended solver. Namely, we have implemented two new features: a power dissipation objective function and a volume constraint. The validity of the volume constraint is successfully tested via a toy problem. Following validation, outputs of the newly modified solver are benchmarked against literature for cases that include a duct system with one inlet and two outlets, an alternate configuration of the same duct system, and a dual bottleneck two-outlet problem. We also include a review of the current literature on topology optimization methods and the implementation of volume constraints in density-based methods.

Comparison and coupling of high-order continuous and hybridzable discontinunous galerkin methods for elliptic problems

Master thesis

Ding, Zichen

Tutor / Supervisor: Giacomini, Matteo; Huerta, Antonio

Publication date: 2020

Barcelona School of Civil Engineering (ETSECCPB)

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Fast solution of parametric incompressible flow problems with application to microfluidics

Master thesis

Borrás Fernández, Álvaro

Tutor / Supervisor: Huerta, Antonio; Giacomini, Matteo

Publication date: 2020

School of Mathematics and Statistics (FME)

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The face-centered finite volume method (FCFV) for steady-state incompressible Navier-Stokes equations

Master thesis

Qin, Shushu

Tutor / Supervisor: Giacomini, Matteo; Huerta, Antonio; Sevilla Cárdenas, Rubén

Publication date: 2019

Barcelona School of Civil Engineering (ETSECCPB)

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Shock-Capturing techniques for Euler equations in the framework of Hybridizable Discontinuous Galerkin

Master thesis

Mohamed Sherif, Ahmed Saeed

Tutor / Supervisor: Huerta, Antonio

Publication date: 2018

Barcelona School of Civil Engineering (ETSECCPB)

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NURBS-Enhanced finite element hybridizable discontinuous Galerkin method with degree adaptivity for steady Stokes flow

Master thesis

Neerala Suresh, Karthik

Tutor / Supervisor: Huerta, Antonio; Sevilla Cárdenas, Rubén

Publication date: 2017

Barcelona School of Civil Engineering (ETSECCPB)

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Implementation of the proper generalized decomposition for hybridizable discontinuous Galerkin

Master thesis

Ribera Manzano, Pablo

Tutor / Supervisor: Huerta, Antonio

Publication date: 2017

School of Mathematics and Statistics (FME)

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HI-FI Hybridisable Discontinuous Galerkin method for incompressible flows

Master thesis

Vila Pérez, Jordi

Tutor / Supervisor: Huerta, Antonio

Publication date: 2017

School of Mathematics and Statistics (FME)

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Real-time analysis of incident wave fields impact to harbor operation

Master thesis

Martínez Casanovas, Josep Maria

Tutor / Supervisor: Huerta, Antonio

Publication date: 2016

Barcelona School of Civil Engineering (ETSECCPB)

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This MSc. thesis presents a novel developed methodology for harbor agitation analysis in real-time. Reduced Order Models are applied for computing a sufficiently accurate generalized solution of the linear elliptic mild-slope equation for any frequency and incoming direction given a modeled harbor. Consequently, a highly efficient process is achieved for evaluating the solution of each incoming wave field (any frequency and any direction) in real-time. To do this, generalized solutions are based on the computation of a reduced basis for the given problem by using the Proper Generalized Decomposition approach. Once computed the reduced basis for a given harbor, the developed methodology proposes the real- time simulation of all possible incident wave fields concerning an incident sea waves spectrum. Two kind of analysis are proposed: the monochromatic and the multi-frequency/multi-directional one. In the first, worst incident directions and frequencies are identiffied, while in the second a combined image of incident waves spectrum is computed and analyzed from a functional point of view. Furthermore, it is valuated the economic impact of the operation conditions regarding the probability of occurrence of the simulated sea climes. At the end of this document two illustrative examples (rectangular harbor and Port Forum harbor) are developed by following the analysis approaches proposed in the previous chapters. As depicted by their results, reduced order models application and the subsequent reduction of computational time is crucial when a lot of solutions are needed. Full range evaluation of different monochromatic incoming waves gives more precise information about harbor response and minimizes signiffcantly the risk of disregarding possible dangerous scenarios. The computation of a unique combined image of a single incident wave spectrum provides a realist way for evaluating real incident sea climes and presents useful outputs for harbor exploitation and optimization. On the whole, the developed approach provides to the harbor management engineers a practical way to optimize and simulate the operative conditions in real harbors, increasing its exploitation profitability and its functional design.