@misc{10481/97364,
year = {2024},
url = {https://hdl.handle.net/10481/97364},
abstract = {This PhD thesis explores the wetting dynamics and behavior of water and
complex fluid droplets on vibrated surfaces, focusing on how substrate vibrations
can be applied to control droplet dynamics, spreading, evaporation,
and particle self-assembly. Central to this investigation is the design
and construction of an experimental setup to study droplet-based systems.
The constructed experimental setup is capable of performing comprehensive
studies on drop shape analysis, center of mass tracking, drop vibration spectroscopy,
Particle Image Velocimetry (PIV), and laser speckle analysis (LSA).
The methodology employed in this research involved the meticulous design of
experimental setups to control and measure droplet behavior under various
conditions. High-speed imaging was used for drop shape analysis, while advanced
tracking algorithms were implemented for center of mass movements.
Precision instruments for vibration spectroscopy allowed for detailed analysis
of droplet oscillations. PIV provided comprehensive flow visualizations within
the droplets, capturing the complex internal dynamics induced by vibrations.
LSA offered high-resolution insights into the micro and nanoscale dynamics
of nanoparticles during evaporation, enabling a detailed understanding of the
underlying processes. The findings reveal that surface properties significantly
affect the motion dynamics of pure water droplets. For instance, elastic substrates
showed reduced asymmetric deformation and facilitated more regular
internal flow, leading to less bulk friction compared to more traditional rigid
substrates. Detailed experiments demonstrated that on superhydrophobic
surfaces, droplets exhibit a terminal speed, allowing for consistent droplet
motion with minimal influence from droplet volume or vibration parameters.
Internal flow dynamics was explored to provide a deeper understanding of the interaction between droplet and substrate. The research indicates that
these factors are crucial in determining the efficiency of droplet transport and
stability across different surfaces.For complex fluids, two primary topics were
investigated: drop spreading and evaporation-induced self-assembly. Experimental investigations revealed that nanofluid drops exhibit unique spreading
behaviors under vibrational forces, which are not observed with pure water
drops. Studies on the effect of hydrophilic and hydrophobized nanofluid drops
showed that nanoparticles significantly alter the drop’s energy landscape, influenced
by NPs-surface interactions that control the spreading process. Vibration
amplitude and particle concentration effects were meticulously analyzed
to build comprehensive drop spreading diagrams based on different
spreading regimes. These diagrams highlighted the critical parameters that
influence spreading dynamics, offering new insights into the behavior of complex
fluids under vibrational forces. Furthermore, the impact of vibration
on the evaporation dynamics and NPs deposition on superhydrophobic surfaces
was rigorously explored. LSA was successfully employed to study NPs
dynamics with improved temporal and spatial resolution, revealing the intricate
patterns of particle movement and deposition. Detailed morphological
and microstructural analyses via Scanning Electron Microscopy (SEM) and
Atomic Force Microscopy (AFM) confirmed that vibrations lead to different
NPs arrangements inside the deposit. The use of vibrations resulted
in smoother and more uniform deposits compared to static conditions, suggesting
a method for controlling deposition patterns. Significant results include
the observation that vibrations enhance the evaporation rate of droplets
by increasing the effective surface area and inducing more efficient mixing
within the droplet. This accelerated evaporation was particularly notable
in nanofluid droplets, where the presence of nanoparticles further altered the
thermal and flow dynamics. The experimental data showed that the combined
effect of vibrations and nanoparticles leads to a distinct evaporation rate. In
conclusion, the research presented in this thesis provides substantial contributions
to the understanding of droplet dynamics under vibrational forces. The
comprehensive experimental and analytical approach adopted in this study offers new perspectives on the behavior of both pure water and complex fluid
droplets, emphasizing the critical role of substrate vibrations. By advancing
the knowledge of droplet dynamics on vibrated surfaces, this thesis lays the
groundwork for further research and development in this field, enhancing our
understanding of fluid dynamics and particle deposition processes.},
organization = {Tesis Univ. Granada.},
organization = {The European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 955612 (NanoPaInt)},
organization = {Project PID2020-116082GB-I00, funded by MCIN AEI 10.13039/50110001103},
organization = {The Biocolloid and Fluid Physics Group (ref. PAI-FQM115) of the University of Granada (Spain)},
organization = {The Arqus Alliance, for financial support during my research stay in Lyon},
publisher = {Universidad de Granada},
title = {Water and complex fluid drop dynamics on vibrating surfaces},
author = {Fusco, Schon Gabriel},
}