Doctoral School

Reading date: 17/07/2026

• BAHRAMIAN, LINDA: Numerical assessment of parcel modeling and inertial particle separator efficiency in polydisperse two-phase flows
  
  Author: BAHRAMIAN, LINDA
  Programme: DOCTORAL DEGREE IN THERMAL ENGINEERING
  Department: Department of Heat Engines (MMT)
  Mode: Normal
  Deposit date: 11/05/2026
  Reading date: 17/07/2026
  Reading time: 11:00
  Reading place: Sala Conferències TR5
  Thesis director: OLIET CASASAYAS, CARLES | PEREZ SEGARRA, CARLOS DAVID
  Thesis abstract: This thesis addresses fundamental and applied aspects of disperse two-phase flow modeling within the Eulerian–Lagrangian approach, with particular emphasis on the development and assessment of parcel modeling and the conservation-consistent two-way coupling approach, progressing toward application of an Inertial Particle Separator (IPS).First, the conservation properties of the two-way coupling formulation are analyzed to ensure consistent momentum exchange between the carrier and dispersed phases. The numerical implementation preserves global conservation principles and physically consistent kinetic energy evolution.The numerical method is first assessed in Direct Numerical Simulation to provide a reference solution and is subsequently extended to Large Eddy Simulation (LES) to address more realistic, application-oriented flow conditions. Building upon this foundation, a novel hybrid parcel modeling strategy is developed by combiningthe Number Fixed Model and the Volume Fixed Model for a particle distribution. The proposed approach is then validated against benchmark cases and offers an effective compromise between computational cost and predictive accuracy.Subsequently, a comprehensive numerical investigation of an IPS device is performed using LES, Improved Delayed Detached Eddy Simulation, and Reynolds-Averaged Navier–Stokes (RANS) turbulence models. The influence of turbulence resolution, flow split ratio, and Reynolds number on separation efficiency is analyzed for different particle sizes. The results indicate that turbulence modeling affects drag-dominated particles, while segregation of larger particles is mainly driven by inertial effects. This study presents a comparative assessment of turbulence modeling strategies and their impact on IPS performance prediction.The numerical framework is then extended to icing conditions. Water droplet impingement and ice accretion are first validated using a canonical cylinder benchmark. The methodology is then applied to the IPS configuration, where ice growth alters the internal geometry. Following ice accretion, solid particles are injected into the modified geometry to evaluate the separation efficiency using Lagrangian tracking, highlighting a reduction in efficiency for inertia-dominated particles as a result of scavenge blockage and modified wall interactions.In this context, a key original contribution of this study is the development and implementation of a dedicated particle–ice wall collision model. To address the lack of suitable models for solid particles impact on ice-covered surfaces in IPS, a restitution-based formulation was developed through a structured review and adaptation of existing collision models.This approach ensures a physically consistent prediction of particle rebound behavior on ice-covered surfaces.Overall, this thesis advances the predictive capability of Computational Fluid Dynamics tools for disperse two-phase flows by enhancing the implementation of conservation-consistent two-way coupling, proposing a physics-guided hybrid parcel model, quantifying the sensitivity of turbulence modeling in IPS efficiency, and introducing a novel particle–wall collision model under adverse icing conditions. The results contribute to both the methodological development of Eulerian–Lagrangian modeling and the reliable simulation of aeronautical particle separation systems.
  

• CUMELLES CÉSPEDES, JOEL: System Identification of High-Performance Paraglider-Harness/Pilot Dynamics: From Modelling to Flight Test Data
  
  Author: CUMELLES CÉSPEDES, JOEL
  Programme: DOCTORAL DEGREE IN AEROSPACE SCIENCE AND TECHNOLOGY
  Department: Department of Physics (FIS)
  Mode: Normal
  Deposit date: 02/06/2026
  Reading date: 17/07/2026
  Reading time: 10:30
  Reading place: Sala C4-001 de l'escola EETAC del campus de Castelldefels
  Thesis director: CASAS PIEDRAFITA, JAIME OSCAR | ORTEGA AGODINO, ENRIQUE
  Thesis abstract: Despite substantial advances in the design, development, and analysis of high-performance paraglider–harness/pilot systems, evaluation methods remain predominantly qualitative and rely heavily on trial-and-error testing. Quantitative in-flight experimental data for these configurations remain scarce, and traditional parafoil–payload models frequently fail to capture the complex geometry, aerodynamic interactions, and dynamic behaviour characteristic of modern high-performance paragliders.This thesis proposes an integrated framework that combines a high-fidelity dynamic model specifically adapted to these systems with a low-cost instrumental platform for model validation using experimental flight data. A nonlinear eight-degrees-of-freedom dynamic model of the high-performance paraglider–harness/pilot system is derived, explicitly incorporating apparent mass effects. Aerodynamic forces and moments are obtained by coupling the model to a computationally efficient horseshoe vortex method solver based on Prandtl’s lifting-line theory and augmented with viscous drag corrections derived from airfoil section polars. This approach enables the direct computation of aerodynamic loads from the actual canopy architecture. Additional refinements are incorporated to improve model fidelity, including a parametric aerodynamic model of the harness/pilot assembly, a generalised aerodynamic drag formulation for the suspension lines, and a distributed representation of brake input along the span and chord.A modular, low-cost, wireless instrumentation platform was developed to support model validation and generate quantitative datasets. This platform integrates distributed accelerometers, gyroscopes, magnetometers, as well as barometric pressure, temperature, and humidity sensors; a GPS module; and a multi-hole probe installed on one of the paraglider suspension lines. The platform was implemented on a commercial high-performance paraglider and evaluated through two dedicated flight-test campaigns.Finally, a system identification approach based on output error methods is implemented to adjust model parameters, enabling comparison of flight data and model predictions across manoeuvres. The results exhibit strong agreement in dynamic response and aerodynamic behaviour, confirming the suitability of the proposed modelling and instrumentation framework. This framework will support future studies of high-performance paraglider–harnesses/pilot systems with quantitative data, thereby enhancing understanding and further development.
  

• KANJ BONGARD, SEBASTIEN: Contribution to the Systematic Study of Threat Actor Tools and Techniques in Real-World Cyber Incidents
  
  Author: KANJ BONGARD, SEBASTIEN
  Programme: DOCTORAL DEGREE IN NETWORK ENGINEERING
  Department: Department of Network Engineering (ENTEL)
  Mode: Normal
  Deposit date: 22/06/2026
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: PEGUEROLES VALLES, JOSEP RAFEL
  Thesis abstract: Cyber incident response and digital forensics (DFIR) research increas- ingly faces a tension between academic rigor and the operational re- alities of real-world investigations. While academic studies often rely on controlled datasets and synthetic scenarios, practitioners must oper- ate under time pressure, incomplete evidence, and strict confidentiality constraints. This doctoral research addresses that gap through an In- dustrial PhD program conducted in collaboration with Incide Digital Data S.L., which enabled access to real-world incident data and practi- tioner workflows while maintaining a rigorous scientific methodology. The thesis investigates how threat-actor tools, techniques, and behaviours can be systematically analyzed and transformed into reusable, vali- dated, and operationally meaningful artifacts. Three complementary research directions are explored. First, an integrated forensic methodol- ogy is proposed for the analysis of abused legitimate tools and mobile activity, combining tool-centric investigations with structured iOS ac- tivity characterization to support accurate reconstruction, automation, and legally robust analysis in real incident-response contexts. Second, the research develops a Business Email Compromise (BEC)-specific map- ping of Tactics, Techniques, and Procedures using the MITRE ATT&CK framework, addressing limitations of narrative-driven BEC reporting. The proposed matrix is validated against real-world cases and demon- strates improved behavioural comparison, clustering, and defensive alignment. Third, the thesis designs and empirically evaluates a YARA- based detection library targeting malware anti-analysis techniques, with a focus on anti-virtual machine and anti-sandbox behaviour, highlight- ing both the strengths and limits of static detection in operational con- texts. Across these contributions, the thesis demonstrates that behavioural and tool-based indicators provide durable defensive value and that hy- brid analytical pipelines are necessary to address modern evasive threats. 6 By grounding methodological innovation in industrial practice, this work advances DFIR towards more systematic, reproducible, and operationally relevant research, supporting faster investigations and more consistent defensive decision-making.
  

• MORELL LLORENS, JOAN: Development of an integrated biological base process for the recovery of copper from electronic waste: Advances in pre-treatment, aeration intensification, monitoring and electrochemical recovery
  
  Author: MORELL LLORENS, JOAN
  Programme: DOCTORAL DEGREE IN NATURAL RESOURCES AND THE ENVIRONMENT
  Department: Department of Mining, Industrial and ICT Engineering (EMIT)
  Mode: Article-based thesis
  Deposit date: 23/06/2026
  Reading date: 17/07/2026
  Reading time: 11:00
  Reading place: Sala d'Actes de l'EPSEM
  Thesis director: DORADO CASTAÑO, ANTONIO DAVID | GUIMERÀ VILLALBA, XAVIER
  Committee:
       PRESIDENT: IGLESIAS GONZALEZ, MARIA NIEVES
       SECRETARI: GAMISANS NOGUERA, XAVIER
       VOCAL: ECHAVARRI BRAVO, VIRGINIA
  Thesis abstract: The accelerated generation of electronic waste (e-waste) represents both a major environmental challenge and an opportunity for the recovery of valuable metals within a circular economy framework. Among the different recovery technologies, bioleaching has emerged as a promising sustainable alternative due to its low energy requirements and reduced dependence on chemical reagents. In particular, closed-loop bioleaching systems enable the continuous regeneration and reuse of the leaching agent, minimizing reagent consumption and waste generation.This doctoral thesis investigates the technological potential and applicability of closed-loop bioleaching for metal recovery from e-waste through an integrated process engineering approach focused on process intensification, operational simplification, continuous monitoring, and integration of downstream metal recovery. The work is structured around four interconnected stages: (I) ferric iron bioproduction, (II) e-waste preprocessing, (III) metal bioleaching, and (IV) selective metal recovery.The first stage addressed was the biological regeneration of ferric iron, responsible for metal oxidation during bioleaching. Since Fe²⁺ oxidation is often limited by oxygen transfer, an intensive aeration system based on a venturi jet was implemented in a bioreactor containing immobilized Acidithiobacillus ferrooxidans. This system significantly increased dissolved oxygen availability and improved Fe²⁺ oxidation rates by up to 3.5 times compared with conventional systems, facilitating a more continuous and intensified operation.The second stage focused on simplifying e-waste preprocessing while maintaining efficient metal recovery. Conventional preprocessing routes often involve extensive mechanical treatment and manual dismantling operations, increasing operational complexity and processing time. Through the characterization of 850 end-of-life mobile phones after industrial shredding and screening processes, it was demonstrated that simplified mechanical strategies can concentrate valuable metals into accessible fractions suitable for subsequent bioleaching stages.During the bioleaching stage, a non-invasive RGB-Arduino device was developed for real-time monitoring of Fe³⁺ and Cu²⁺ concentrations through optical analysis. The system enabled analyte estimation under highly corrosive conditions without continuous sampling, facilitating process control and reducing waiting times between stages.Finally, the thesis demonstrates the feasibility of direct copper electrowinning from iron-rich leachates without prior iron removal. Although the presence of Fe²⁺ affects current efficiency, copper deposits with purities close to 99.9% were obtained. Furthermore, the remaining Fe²⁺ in solution can be recirculated back to the biological oxidation stage, where it is regenerated to Fe³⁺ and reused as the leaching agent. This strategy closes the iron loop, minimizes reagent consumption, and reduces secondary waste generation.Overall, this thesis contributes to the development of a more compact, efficient, and operationally simplified closed-loop bioleaching process for sustainable urban mining and e-waste recycling.
  

• NEPAL, ANIMESH: Origins of interface jumps, pinning and hysteresis during cyclic fluid displacements
  
  Author: NEPAL, ANIMESH
  Programme: DOCTORAL DEGREE IN GEOTECHNICAL ENGINEERING
  Department: Department of Civil and Environmental Engineering (DECA)
  Mode: Normal
  Deposit date: 09/06/2026
  Reading date: 17/07/2026
  Reading time: 10:30
  Reading place: ETSECCPB.UPC, Campus NordBuilding B1. Classroom: 003C/Jordi Girona, 1-308034 Barcelona
  Thesis director: DENTZ, MARCO | HIDALGO GONZÁLEZ, JUAN JOSÉ
  Thesis abstract: Immiscible fluid displacements in porous media is governed by the interplay of capillary forces, pore geometry, wettability, and driving conditions. Under quasistatic conditions, this interplay gives rise to metastable interfacial configurations, abrupt interface rearrangements (Haines jumps), interface pinning, and macroscopic pressure--saturation hysteresis. This thesis develops a pore-scale framework to explain how these phenomena emerge and how they can be predicted. The work combines laboratory experiments, numerical simulations in two and three spatial dimensions, and analytical models derived from hydrostatic--capillary pressure balance and interfacial energy arguments. The investigation progresses from simple geometries representing a single pore (ink-bottle and wavy capillaries) to connected porous media (homogeneous and heterogeneous porous media), allowing direct identification of fundamental mechanisms and their collective effects.In single-pore ink-bottle geometries, the results show that interfacial behavior is controlled by a critical geometric condition: below this threshold, interfaces evolve smoothly, whereas above it, interfaces become unstable and jump, resulting in hysteresis during imbibition and drainage. The occurrence and magnitude of jumps depend systematically on the contact angle, surface tension, and constriction angle, and are accurately captured by theory. The thesis then demonstrates that driving mode is also a primary control parameter by analyzing two different capillaries (ink-bottle and wavy capillary tube). Under pressure-driven cyclic displacement, jumps and hysteresis arise from the loss of interfacial stability. Under volume-driven displacement, however, imposed volume constraints suppress jump transitions, eliminate capillary hysteresis, and force the interface to retrace identical imbibition and drainage paths, while interfacial pinning can still occur. In the volume-driven regime, the fluid can traverse tensile and otherwise inaccessible interfacial configurations that are inaccessible under pressure-driven fluid displacement, confirming that the choice of driving mode can decouple pinning and hysteresis. In wavy capillaries, smooth curvature change prevents interface pinning, but pressure-driven displacement can still trigger interfacial jumps. An energy-based analysis shows that pressure changes drive saddle-node transitions between local energy minima, producing jumps and hysteresis. This yields a simple jump criterion that links contact angle to wavy-capillary geometry. Extending these insights to porous media, the thesis shows that homogeneous pore channels can be represented with wavy-capillaries that reproduce key pressure--saturation signatures, including jumps and hysteresis. In heterogeneous porous media, stronger geometric variability generates intermittent collective rearrangements, also known as Haines jump, hysteresis, and return-point memory during internal cycles, evidencing a rugged energy landscape with history-dependent pathways. Together, these results establish a coherent mechanistic link between pore-scale metastability and macroscopic hysteresis. The framework provides predictive tools for controlling displacement efficiency and energy dissipation in applications such as CO$_2$ sequestration, enhanced oil recovery, microfluidics, and capillary transport in natural and engineered porous media.