Sotiris Panagiotis Evgenidis

Aristotle University of Thessaloniki | AUTH · School of Chemistry

Emulsions are encountered in foods, cosmetics and pharmaceuticals. Their stability depends strongly on gravity (creaming or sedimentation) and interface driven destabilization mechanisms (coalescence or aggregation) occurring after their production. Although of great significance, coalescence and aggregation cannot be studied in-depth on ground due...

Silane-based materials are used for the protection of heritage and modern buildings. A versatile method is developed to tune the wetting properties of a typical silane-based material from hydrophobicity to superamphiphobicity, thus enhancing the protective efficacy against rainwater and organic pollutants. A commercially available silane product is...

This study aims to develop a phantom that simulates the electrical properties of a human blood vessel surrounded by tissues, inside which bubbles can be infused to mimic Decompression Sickness (DCS) conditions. This phantom may be used to calibrate novel electrical methods for bubbles detection in humans and study bubble dynamics during DCS. It may...

Background: This work performs two-dimensional Computational Fluid Dynamics (CFD) simulations of pulsatile bubbly flow in a column resembling the flow inside human vena cava during Decompression Sickness (DCS), aiming to illustrate the effect of certain parameters in bubbly blood flow and so facilitate the design of the: a) corresponding in-vitro...

Dietary nutrition and uptake of earth-like foods are extremely important aspects for the health and performance of astronauts, especially during future planned long-term space missions. Despite the major progress in studying and designing systems for crop cultivation in microgravity conditions in the last years, there hasn’t been equal interest in...

This work compares four different image processing algorithms for the analysis of image data obtained during the Multiscale Boiling Experiment of ESA, executed on-board the International Space Station. Two separate experimental campaigns have been performed in 2019 and 2020, aiming to investigate boiling phenomena in microgravity, with and without...

This publication lays the foundation for the description of the Multiscale Boiling Experiment, which was conducted within two measurement campaigns on the International Space Station between 2019 and 2021. The experiment addresses fundamental questions about two-phase heat transfer during boiling processes. For this purpose, single or few subsequen...

The goal of the study was to characterize the limestone that was used extensively in the ancient city of Pella (Macedonia, Greece), the birthplace of Alexander the Great. An on-site examination of the building material was carried out to record the types of damage and to select sampling areas. A variation in the nature of the stone and the degree o...

Chemical composition measurement technologies for binary systems are needed in many industrial and research applications for monitoring fluid composition in pipes and sample analysis. Except for spectroscopy technology, composition measurement is retrieved by monitoring fluid properties as refractive index, density, electrical conductivity or fluid...

Process modeling is a valuable tool for process design and optimization. Nonetheless, the extent of its use depends on the physical complexity of each particular application. Flotation is one of the most complex processes to model. In particular, in mechanical flotation cells, turbulent flow prevails and promotes bubble particle collisions. Many si...

This study investigates the behaviour of bubble clusters rising among single bubbles in a non-Newtonian liquid, employing: a) an ultra-sensitive electrical impedance spectroscopy technique for obtaining void fraction time-series and b) an optical method for estimating cluster size and shape. Bubble clusters cause intense void fraction signal peaks....

The aim of this study is the development of an emulsification device for two immiscible liquids with a total volume of approximately 3 mL. The heart of the device is a piston, with an aluminum plate fixed at its tip, which moves periodically up and down inside a rectangular cell. The plate geometry (uniform or non-uniform height) affects significan...

This work studies gas–liquid flow of small bubbles (<1 mm) at low void fractions (<10⁻¹) that is encountered in human bloodstream during Decompression Sickness and is also relevant to two-phase applications such as flow boiling in macro-channels. Two fundamental parameters are experimentally investigated: Bubble Size Distribution (BSD) and void fra...

Drift-flux model is a simple and reliable tool for void fraction prediction in two-phase flows. This work examines its performance in gas-liquid flow of small bubbles (<1 mm) at low void fractions (<10 ⁻¹) that resembles bubbly flow in human bloodstream during Decompression Sickness and can be also found in other two-phase applications such as flow...

Despite the extensive study of wetting in literature, there are still many unresolved issues regarding forced wetting. One of them refers to the effect of the initial droplet shape on the force required for spreading and sliding along a solid surface; an effect that has not ever been explicitly reported. Previous experimental works, in general, ass...

6th International Workshop on Bubble and Drop Interfaces, Potsdam/Golm, Germany

It is known that bubble size affects seriously the average void fraction in bubbly flows where buoyant velocities vary considerably with bubble size. On the contrary, there is no systematic literature report about bubble size effects on the intensity and frequency of void fraction fluctuations around the average void fraction. This work aims to pro...

COST action - Smart and Green Interfaces 2013 workshop, Prague, Czech Republic, March 21-22, 2013

This work presents experiments for the estimation of heat transfer from sub-millimeter spheroidal heaters at varying gravity conditions. Experiments were performed during the 50th Parabolic Flight Campaign of European Space Agency (May 2009). Heat pulses of varying strength were given to a miniature heater submerged in the liquid while its thermal...

This work presents experiments in a bubbly flow comparable to the one observed during decompression sickness (DCS) in humans. Experiments are conducted in a tube dimensionally similar to vena cava of the human body with liquids of various properties (surface tension, viscosity, conductivity) and liquid flow rates equivalent to those of human blood...

Gas bubbles can be generated on solid surfaces covered by a liquid as a result of desorption of dissolved gases when the liquid becomes supersaturated with respect to dissolved gases. This work starts from basic phenomena controlling single bubble growth on a solid surface, extends to growth of multiple adjacent bubbles and their subsequent detachm...

This work investigates the behavior of small liquid bridges that are formed between two horizontal supporting surfaces, aligned at the vertical direction. The contact lines of the liquid bridges are not edge-pinned but free to move across the supporting surfaces with the contact angle as a parameter (theta-bridges). An a.c. electrical conductance t...