3D waves of falling films using the CODE BLUE.
Results on formation of surfactant-laden drops from University of Birmingham have been presented at 30th Conference of The European Colloid and Interface Society ECIS-2016, Rome, 4-9 September 2016. Abstract Effect of soluble surfactants of kinetics of liquid bridges and formation of satellite droplets N Kovalchuk, E Nowak, M.J.H. Simmons School of Chemical Engineering, University of Birmingham, UK Bespoke drop formation is an essential part of many industrial processes such as emulsification, spray drying, inkjet printing and others. Surfactants are often present in the aqueous formulations used in these processes and therefore influence the quality of the final product. In particular [ Read More ]
New article on Physical Review E explaining the effect of surfactants on the neck expansion dynamics and the flow field around the rupture point has been published! Abstract: In this work the coalescence of an aqueous drop with a flat aqueous-organic interface was investigated in a thin gap Hele-Shaw cell. Different concentrations of a nonionic surfactant (Span 80) dissolved in the organic phase were studied. We present experimental results on the velocity field inside a coalescing droplet in the presence of surfactants. The evolution of the neck between the drop and the interface was studied with high-speed imaging. It was found that [ Read More ]
A short presentation summarising the main results of the paper “Effect of Soluble Surfactants on the Kinetics of Thinning of Liquid Bridges during Drops Formation and on Size of Satellite Droplets” by Nina Kovalchuk, Emilia Novak and Mark Simmons recently published in Langmuir is now available as the LiveSlides on Langmuir web-site and is directly connected to this open access paper.
This animation shows the reconstructed interfacial wave structure in a falling liquid film using Multi-Pin Film Sensor (MPFS). MPFS comprises of 2 X 5 axial planes x 64 circumferential pin electrodes (i.e. 640 points measurement). MPFS can provide film thickness data with high temporal and spatial distribution for upward /downward annular flows in time, circumferential and axial coordinates, δ(t,θ,z). The pipe diameter used was 127 mm. The animation shows non-coherent wave structure.
1) A paper “Transition from stratified to non-stratified oil–water flows using a bluff body” by Kyeong Hyeon Park, Maxime Chinaud and Panagiota Angeli has been published in Experimental Thermal and Fluid Science. In this paper the effect of a transverse cylindrical rod immersed in water on the flow patterns and interfacial characteristics of an oil–water pipe flow is investigated experimentally. The cylinder is used to passively actuate the transition from stratified to non-stratified flows and to localise the formation of waves and the detachment of drops. The studies are carried out in an acrylic test section with 37 mm ID [ Read More ]
A paper “Effect of surfactant concentration and viscosity of outer phase during the coalescence of a surfactant-laden drop with a surfactant-free drop” by Emilia Nowak, Nina Kovalchuk, Zhizhao Che and Mark Simmons have been published in Colloids and Surfaces A: Physicochemical and Engineering Aspects. The paper is a result of collaborations between the University of Birmingham and Imperial College London. Abstract This work focuses on the coalescence of two water drops, one of which contains surfactant. The coalescence was carried out in surrounding silicone oils of various viscosities. It has been found that, in all the studied cases, the outward [ Read More ]
Memphis Programme well represented at the ICMF 2016 International Conference on Multiphase Flow, Florence, Italy, May 22 – 27, 2016. THE NEXT-GENERATION PREDICTIVE TOOLS FOR MULTIPHASE FLOWS by Omar K. Matar, Imperial College London, UK. The ability to predict the behaviour of multiphase flows accurately, reliably, and efficiently addresses a major challenge of global economic, scientific, and societal importance. These flows are central to micro-fluidics, virtually every processing and manufacturing technology, oil and-gas, nuclear, and biomedical applications. Significant advances have been made in the numerical procedures to simulate these flows; examples of these include the use of Large Eddy [ Read More ]
The team of the University of Birmingham has published a paper “Effect of Soluble Surfactants on the Kinetics of Thinning of Liquid Bridges during Drops Formation and on Size of Satellite Droplets“ in Langmuir. Abstract The results of an experimental study on thinning and breakage of liquid bridges during detachment of a drop from the tip of a capillary are presented for a series of surfactant solutions (including cationic, anionic, and nonionic surfactants) over a broad range of molecular masses, values of critical micelle concentration, and concentrations. The used experimental protocol revealed that the kinetics of the bridge thinning depends much more on the [ Read More ]