The presence of even a small amount of surfactant at the particle-laden fluid interface subjected to shear makes surface flow incompressible if the shear rate is small enough [T. M. Fischer et al., J. Fluid Mech. 558, 451 (2006)]. In the present paper the effective surface shear viscosity of a flat, low-concentration, particle-laden incompressible interface separating two immiscible fluids is calculated. The resulting value is found to be 7.6% larger than the value obtained without account for surface incompressibility.
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http://dx.doi.org/10.1103/PhysRevE.89.043003 | DOI Listing |
Langmuir
November 2024
Chemical and Biomolecular Engineering Department, University of California, Berkeley, Berkeley, California 94760, United States.
Particle-laden interfaces stabilize emulsions and foams and can serve as a platform for multiscale materials. Favorable wetting of a particle to a fluid interface reduces the apparent interfacial tension through area replacement with a linear relationship between the apparent surface pressure and the particle area fraction. The area replacement model is widely employed, often up to particle area fraction reaching the maximum hexagonal packing.
View Article and Find Full Text PDFAdv Sci (Weinh)
December 2024
Institut für Physikalische Chemie I: Kolloide und Nanooptik, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225, Düsseldorf, Germany.
Thin films made of deformable micro- and nano-units, such as biological membranes, polymer interfaces, and particle-laden liquid surfaces, exhibit a complex behavior during drying, with consequences for various applications like wound healing, coating technologies, and additive manufacturing. Studying the drying dynamics and structural changes of soft colloidal films thus holds the potential to yield valuable insights to achieve improvements for applications. In this study, interfacial monolayers of core-shell (CS) microgels with varying degrees of softness are employed as model systems and to investigate their drying behavior on differently modified solid substrates (hydrophobic vs hydrophilic).
View Article and Find Full Text PDFData Brief
October 2024
Department of Fluid Mechanics, Universitat Politècnica de Catalunya · BarcelonaTech (UPC), Barcelona 08019, Spain.
Plastic particle pollution has threatened the well-being of seawater ecosystems over the past decades. Therefore, understanding, modeling and (potentially) predicting the dynamics of microplastics and biogenic particles in ocean turbulence is of utmost importance to help develop mitigation strategies and propose technological solutions ultimately aimed at safeguarding global water systems. This is particularly significant for microplastics in the upper-ocean layer.
View Article and Find Full Text PDFSoft Matter
September 2024
Food Colloids and Processing Group, School of Food Science and Nutrition, University of Leeds, Leeds LS2 9JT, UK.
Pickering emulsions are ultra-stable dispersions of two immiscible fluids stabilized by solid or microgel particles rather than molecular surfactants. Although their ultra-stability is a signature performance indicator, often such high stability hinders their demulsification, , prevents the droplet coalescence that is needed for phase separation on demand, or release of the active ingredients encapsulated within droplets and/or to recover the particles themselves, which may be catalysts, for example. This review aims to provide theoretical and experimental insights on demulsification of Pickering emulsions, in particular identifying the mechanisms of particle dislodgment from the interface in biological and non-biological applications.
View Article and Find Full Text PDFMicromachines (Basel)
June 2024
Institute of Turbomachinery, Faculty for Mechanical Engineering and Ship Design, University of Rostock, 18059 Rostock, Germany.
For the optimization of ventricular assist devices (VADs), flow simulations are crucial. Typically, these simulations assume single-phase flow to represent blood flow. However, blood consists of plasma and blood cells, making it a multiphase flow.
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