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The thermocapillary-driven core release of double-emulsion droplets offers advantages such as simplicity in implementation and a broad range of applications, providing unique strengths in the field of core component release. However, the characteristics and mechanisms related to thermocapillary-driven core release were still unknown. This article employed the Volume of Fluid method to investigate the core release characteristics of double-emulsion droplets driven by thermocapillary. The range of Marangoni (Ma) numbers is from 10 to 500. The results indicate that effective control of the migration and release dynamics of double-emulsion droplets can be achieved through viscosity regulation, which induces the obvious difference between the two types of double-emulsion droplets. The regulation of both viscosity and surface tension is efficient in controlling the release type of the core. A phase diagram distinguishing between one-off and two-off release types is presented. Additionally, by characterizing dimensionless numbers, a formula for the characteristic release time of double-emulsion droplets is derived. The current study contributes to achieving precise control of double-emulsion droplets, expanding the scope of applications for double-emulsion droplets and establishing a fundamental groundwork for subsequent investigations into the release methods of double-emulsion droplets driven by thermocapillary. [ABSTRACT FROM AUTHOR]

This study investigates the pattern-forming behavior of ferrofluid droplets under the influence of radial magnetic fields. The experimental setup involves depositing initially circular ferrofluid drops surrounded by an immiscible nonmagnetic fluid on a plate with an electromagnet placed below. Through systematic experimentation and theoretical analysis, we explore the effects of two distinct radial magnetic fields on the outer and inner shapes of the droplets. Results reveal the emergence of various intricate interface patterns, including spike-like structures and fingerlike protrusions, as the magnetic Bond number and droplet initial diameter vary. The experimental observations are supported by theoretical predictions derived from mode-coupling differential equations, which provide insight into the underlying dynamics governing pattern formation. This study sheds light on the complex interplay between magnetic and hydrodynamic effects in ferrofluid systems, with implications for diverse applications ranging from microfluidics to biomedical engineering. [ABSTRACT FROM AUTHOR]

This paper first prepared a water-based magnetic fluid using a chemical co-precipitation method and conducted a detailed characterization and calculation of its important magnetization properties. Key parameters for analyzing the influence mechanism on the rheological properties of the water-based magnetic fluid were obtained. Subsequently, the impact of different magnetic field and shear rates on the magnetoviscous effect, shear-thinning behavior, and yield stress of the water-based magnetic fluid was studied through steady rotation measurements. The results showed a positive correlation between viscosity, shear stress, and yield stress with the magnetic field. Additionally, we also provide theoretical prediction formulas for the magnetoviscous effect based on the influence of microstructures formed by solid-phase magnetic particles in the magnetic field. The dimensionless Mason number was used to establish the scaling law relationship between viscosity measurements and theoretical values, with results showing good agreement between measured and theoretical values. The Herschel–Bulkley model and the Casson model were employed to obtain the dynamic yield stress values of the sample, and a quadratic linear increase relationship between yield stress and magnetic field was derived. These research findings provide important references for a deeper understanding of the physical and chemical properties of water-based magnetic fluid and for optimizing its application. [ABSTRACT FROM AUTHOR]