Research into Multi-scale Examination of MultiPHase physIcs in flowS (MEMPHIS)

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Velocity field after coalescence of water droplet on an oil-water interface

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Domain decomposition over 163 = 4096 subdomains

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Droplet dynamics in stratifying horizontal gas-liquid flow

24 May 2017
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It is with great sadness we inform you that Prof Barry Azzopardi passed away on Monday morning the 22nd May after his long illness and battle with cancer. Throughout his battle, Barry continued to work with and support the MEMPHIS Programme. He is in our thoughts and will be greatly missed.         https://www.nottingham.ac.uk/engineering/people/barry.azzopardi   Please email Helen Giberson (helen.giberson@nottingham.ac.uk) or David Large (david.large@nottingham.ac.uk) for details of the funeral

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9 May 2017

Paper “Experimental Investigations of Non-Newtonian/Newtonian Liquid-Liquid Flows in microchannels” has been published in AiChE Journal Evangelia Roumpea, Maxime Chinaud, Panagiota Angeli   Abstract The plug flow of a non-Newtonian and a Newtonian liquid was experimentally investigated in a quartz microchannel (200-µm internal diameter). Two aqueous glycerol solutions containing xanthan gum at 1000 and 2000 ppm were the non-Newtonian fluids and 0.0046 Pa s silicone oil was the Newtonian phase forming the dispersed plugs. Two-color particle image velocimetry was used to obtain the hydrodynamic characteristics and the velocity profiles in both phases under different fluid flow rates. The experimental results revealed  [ Read More ]

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8 May 2017

The interfacial wave structure of the liquid phase in both upwards and downwards gas-liquid flows in an 11.7 mm pipe were investigated using the Brightness Based Laser Induced Fluorescence technique (BBLIF). Due to the versatility of the BBLIF technique, film thickness measurements were carried out over different axial locations covering a measurement area with very high spatial and temporal resolution. More specifically this comprises of measurements obtained between 330-430 mm from the inlet (between 28 to 37 z/D), where the flow is close to a fully developed condition. As extensively reported in literature, increasing the gas superficial velocity results in  [ Read More ]

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4 May 2017

Microfluidic devices occur in a large variety of applications in chemical, medical and pharmaceutical process such as inkjet printing, DNA chips, lab-on-a-chip technology, micro-propulsion and droplet-based microfluidics. Due to the small size of these microchannel, the flow is dominated by the viscous and interfacial forces more than inertial and gravity forces.   We examine drop, pancake, plug and jet formation of immiscible liquids in a cross-shaped microchannel with direct numerical simulations using the new solver, BLUE, for massively parallel simulations of fully three-dimensional multiphase flows in complex solid geometries. The figure above shows an experimental flow pattern map with few  [ Read More ]

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24 Apr 2017

Displacement of one fluid by another one (miscible or immiscible) is of great industrial importance. Examples can be the pipe cleaning or enhanced oil recovery. In the framework of MEMPHIS the liquid displacement is studied in micro-channels by PhD student Yu Lu. It was discovered that displacement is accompanied by series of instabilities presented in Figures below. The instabilities can change considerably the performance of displacement and therefore should be always taken into consideration. Figure 1. Three flow regimes for immiscible fluid pairs: 100 cSt silicone oil is displaced by water. The Reynolds number for displacing liquid Re2 is changed  [ Read More ]

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8 Mar 2017

This year, as the final year of Multi-scale Examination of MultiPHase physIcs in flowS (Memphis), we celebrate and showcase our success from the past 4-5 years. The showcase will be held at Imperial College and will feature presentations by industrialists (P&G and BP) and academics / researchers (from ICL, UoB, UoN, and UCL) and cover the remarkable output from the Memphis Programme and the technical innovations it has generated for industry. Although some advances have been made in the numerical methods used to simulate multiphase flows, there remains a large gap between what is achievable computationally and ‘real-life’ systems; the  [ Read More ]

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1 Mar 2017

Many industrial products, i.e. milk, paint and shampoo, are emulsion-based systems and require drops of a preferred size. Microfluidic devices, such as flow-focusing channels, can provide narrow drop size distributions. In many cases surfactants are used to stabilise the emulsions, which  add complexity to the drop formation process. At UCL we investigate the hydrodynamic characteristics and velocity profiles of aqueous drops in a flow-focusing device with and without surfactants present. This study is part of a collaborative work with the University of Birmingham, within the MEMPHIS framework. Silicone oil (μ = 0.0046 Pa s, Sigma-Aldrich) was used as a continuous  [ Read More ]

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27 Feb 2017

The animation below shows the interfacial wave structure in circumferential direction of a falling liquid (water) film using Multi-Pin Film Sensor (for more details on experimental setup, see my previous post on the following link):   http://www.memphis-multiphase.org/reconstructed-images-of-the-evolved-wave-in-time-for-the-liquid-falling-film-along-the-pipe/   This animation was taken at liquid Reynolds number, ReL=1670. The inner diameter of the test section is 127 mm. Unlike small diameter pipes where the waves are characterised as coherent rings, the waves found in this study with large diameter pipe are more localized.   [click on the image]    

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24 Feb 2017

Microfluidics enables formation of emulsions and foams with drops/bubbles of a submillimetre size and a narrow size distribution. Surfactants are usually used in emulsification/foaming processes to protect drops/bubbles against coalescence through creating protective adsorption layers on the phase interfaces. However, a recent study performed at the University of Birmingham has shown that a protective surfactant layer does not always work when drops are moving in the confined geometry of microchannel. Frequent coalescence events were in particular observed in the channels with their height smaller than their width for surfactant-laden drops larger than the channel height. An example of such coalescence is  [ Read More ]

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31 Jan 2017

  The Figure above shows a three-dimensional direct numerical simulation of an annular falling film reactor in a situation of a clean interface (left), insoluble (center) and soluble (right) surfactant. We adapt and extend a formulation for soluble surfactant transport in multiphase flows recently presented by Muradoglu & Tryggvason (JCP 274 (2014) 737-757) to the context of the Level Contour Reconstruction Method (Shin et al. IJNMF 60 (2009) 753-778) which is a hybrid method that combines the advantages of the Front Tracking and Level Set methods. Particularly close attention was paid to the formulation and numerical implementation of the surface  [ Read More ]

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