“Each piece, or part, of the whole nature is always merely an approximation to the complete truth, or the complete truth so far as we know it. In fact, everything we know is only some kind of approximation because we know that we do not know all the laws as yet”
— Richard P. Feynman
In the Complex Fluids Lab, we study interfacial fluid phenomena at the micro/nano scale for developing micro/nano technology. These studies encompass the formation, instability and fragmentation of micro-threads, micro-emulsions, micro-droplets, micro-bubbles, and related phenomena. We adopt an interdisciplinary approach that integrates theory, numerical simulations and experiments by utilizing state-of-the-art equipment including our high-speed microscope visualization set-up. This comprehensive strategy enables us to integrate our cutting-edge fundamental research with innovation to address critical sustainability and healthcare challenges. For instance, key applications include CO2-free hydrogen technology, soft robotics, and drug delivery, among many others. Our UPM affiliations are:
Department of Mechanical, Chemical, and Industrial Design Engineering, Universidad Politécnica de Madrid, Ronda de Valencia 3, 28012 Madrid, Spain
Thermal Energy for Sustainability group, Universidad Politécnica de Madrid, José Gutiérrez Abascal 2, 28006 Madrid, Spain
Current research
Fundamentals on microscopic interfacial fluid dynamics
The physics of droplets, bubbles, jets, and related fluid phenomena at very tiny scales is not only fascinating but also essential to developing innovative solutions to overcome the current challenges of key technological applications across scales (Cruz-Mazo et al. (2019) Phys. Rev. E). An excellent example comes from the fact that a fluid-fluid interface cannot be considered infinitely narrow within fluid fragmentation as we showed, together with our derivation of a new set of self-similar equations that also resolved for the jet pinch-off as the finite-thickness of the interface becomes comparable to the characteristic radial size (Cruz-Mazo & Stone (2022) Phys. Rev. Fluids).
Interdisciplinary micro/nano fluid flows
Controlled microscopic fluid entities and their on-demand production are present in a multitude of technologies. Both the development of novel approaches and the customization of our methods require collaborative projects that bridge fundamental and applied research in an interdisciplinary way:
Sustainable hydrogen production is one of the endeavors of the TE4S group, where we contribute because of our METAHL-BUBS project: a “Generación de Conocimiento” National Research Grant (PID2023-151272OA-I00: PIs Luis González & Francisco Cruz-Mazo) that aims to research the “Modeling and Experimental Techniques for Advanced Heating in Liquid-metal Bubble Systems“.
Biotechnology is the general applied field where our current interdisciplinary project proposal, BEEflow, aims to focus on by developing novel microscopic fluid devices. Other related works under this general scope embrace the efficient transport of bio-substances with ultra-fast sub-micron-sized liquid jets for structural biology via serial femtosecond crystallography with x-ray free-electron lasers (Holmes et al. (2022) Nature Commun.)
A complete list of Cruz-Mazo’s publications and their citations is available @googlescholar.
People
PhD Students
Alberto Aspas (since 2026) is an incoming PhD student at INTA, co-supervised by Adelaida García-Magariño and F. Cruz-Mazo, under the PhD programme ETSI Navales. He works on drag reduction via microbubbles.
Añaterve Oval (since 2025) is an Industrial PhD student at ARQUIMEA, co-supervised by Leo González and F. Cruz-Mazo, under the PhD programme ETSI Navales. He works on advanced methods of fluid-structure interaction for soft-robotics applications.
MSc Students
Tommaso Romagno (since 2026) is a visiting TFM student from Politecnico di Bari. He works on fluid measurement.
Undergraduate Students
Marina Bielsa (since 2026) is an incoming TFG student in Chemical Engineering.
Cristina Boned (since 2026) is an incoming TFG student in Electronics Engineering.
Gabriel Toledo (since 2026) is a collaborative Mechanical Engineering student.
Nicolás Jiménez (since 2025) is a TFG student in Electronics Engineering. He works on fluid control methods.
Beatriz Galán (since 2025) is a TFG student in Chemical Engineering. She works on non-newtonian flows.
Alicia Bermejo (since 2025) is a TFG student in Chemical Engineering. She works on micro-droplets.
Moneiba Marrero (since 2025) is a TFG student in Chemical Engineering. She works on droplets.
Diego Berlanga (since 2025) is a TFG student in Chemical Engineering. He works on bubbles.
Juan de Frutos (since 2025) is a TFG student in Mechanical Engineering. He works on bubbles.
Eduardo Viejo (since 2025) is a TFG student in Chemical Engineering. He works on fluid mixing.
Alberto González-Garrido (since 2025) is a TFG student in Mechanical Engineering. He works on fluid measurement.
Alumni
Miguel Martín (BSc thesis 2026) – Daniel Farfán (MSc thesis 2026) –Pablo Fernández (BSc thesis 2025) – Livio Mösch (MSc thesis 2024) – Carlos Martins (BSc thesis 2024) – Candela Ramos (BSc thesis 2024) – Lucía Suárez (BSc thesis 2024) – Marcos Arroyo (BSc thesis 2024) – Alberto Pavón (BSc thesis 2024) – Mario Gutiérrez (BSc thesis 2024) – Marcos Albarrán (BSc thesis 2024) – Pablo Rodríguez (BSc thesis 2024) – Leire Chapartegui (BSc thesis 2023) – Salvatore Regusa (BSc thesis 2023) – Alberto Díaz (MSc thesis 2023) – Alejandro Álvarez (BSc thesis 2023)
