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X-ray tomography for fully-3D time-resolved reconstruction of bubbling fluidized beds

Graas, Adriaan B.M. (author), Wagner, E.C. (author), van Leeuwen, Tristan (author), van Ommen, J.R. (author), Batenburg, K. Joost (author), Lucka, Felix (author), Portela, L. (author)

A new X-ray computed tomography technique for the purpose of imaging fluidized beds is presented. It consists of an experimental set-up with three stationary X-ray source and flat panel detector pairs, a geometric calibration and data processing workflow, and an image reconstruction algorithm. The technique enables sparse-angular tomographic...

journal article 2024

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Diffusion across particle-laden interfaces in Pickering droplets

Liu, Y. (author), Xu, M. (author), Portela, L. (author), Garbin, V. (author)

Emulsions stabilized by nanoparticles, known as Pickering emulsions, exhibit remarkable stability, which enables applications ranging from encapsulation, to advanced materials, to chemical conversion. The layer of nanoparticles at the interface of Pickering droplets is a semi-permeable barrier between the two liquid phases, which can affect the...

journal article 2023

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Metabolic-fluid dynamics model construction and scale-down design for an industrial penicillin chrysogenum fermentation with combined dissolved oxygen and glucose concentration dynamics

Wei, P. (author), Haringa, C. (author), Portela, L. (author), Noorman, H.J. (author)

This study focuses on the metabolic impacts of simultaneous glucose and oxygen concentration gradients on penicillin production in an industrial-scale fermentor, using the computational fluid dynamics-cellular reaction dynamics approach. Inclusion of oxygen-coupling considerably impacts the glucose uptake and resulting penicillin productivity...

journal article 2023

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Effect of N₂ and CO₂ bubbles on gas volume fraction and flow pattern in a quasi-2D bubble column by shadow imaging

Sarker, D. (author), Schinkel, C.V. (author), Portela, L. (author)

This study reports the effect of N₂ and CO₂ bubbles on dilute to dense gas-liquid two-phase bubbly flow. A shadowgraph imaging technique captured bubble images at a high spatiotemporal resolution. The recordings of bubble images allow us to compute gas fraction distribution. It requires challenging segmentation and gas...

journal article 2023

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Predicting the influence of geometric imperfections on the mechanical response of 2D and 3D periodic trusses

Glaesener, R. N. (author), Kumar, Siddhant (author), Lestringant, C. (author), Butruille, T. (author), Portela, C. M. (author), Kochmann, D. M. (author)

Although architected materials based on truss networks have been shown to possess advantageous or extreme mechanical properties, those can be highly affected by tolerances and uncertainties in the manufacturing process, which are usually neglected during the design phase. Deterministic computational tools typically design structures with the...

journal article 2023

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Electrolyte and temperature effects in a rising bubble

Mandalahalli, M.M. (author), Lif, Johan (author), Mudde, R.F. (author), Portela, L. (author)

In this work, the rise characteristics of a single H₂ bubble, in the ellipsoidal regime, in (i) water, (ii) single electrolyte (2 M, 4.5 M NaCl) solution and (iii) various concentrations of electrolyte mixture (up to 6.4 M of 1:5 weight fraction NaCl-NaClO₃), have been studied, at temperatures up to 80°C. Our results...

journal article 2023

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Correlation and decomposition concepts for identifying and disentangling flow structures: Framework and insights into turbulence organization

Mukherjee, S. (author), Mascini, Merlijn (author), Portela, L. (author)

Turbulence and its organization, long conceptualized in terms of "coherent structures,"has resisted clear description. A significant limitation has been the lack of tools to identify instantaneous, spatially finite structures, while unraveling their superposition. We present a framework of generalized correlations, which can be used to...

journal article 2022

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A Fast Electrical Resistivity-Based Algorithm to Measure and Visualize Two-Phase Swirling Flows

Sattar, Muhammad Awais (author), Martinez Garcia, M. (author), Portela, L. (author), Babout, Laurent (author)

Electrical resistance tomography (ERT) has been used in the literature to monitor the gas–liquid separation. However, the image reconstruction algorithms used in the studies take a considerable amount of time to generate the tomograms, which is far above the time scales of the flow inside the inline separator and, as a consequence, the...

journal article 2022

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Towards Tomography-Based Real-Time Control of Multiphase Flows: A Proof of Concept in Inline Fluid Separation

Martinez Garcia, M. (author), Sattar, M.A. (author), Atmani, Hanane (author), Legendre, Dominique (author), Babout, Laurent (author), Schleicher, Eckhard (author), Hampel, Uwe (author), Portela, L. (author)

The performance of multiphase flow processes is often determined by the distribution of phases inside the equipment. However, controllers in the field are typically implemented based on flow variables, which are simpler to measure, but indirectly connected to performance (e.g., pressure). Tomography has been used in the study of the...

journal article 2022

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Dynamics of suspended sediment transport: A Direct Numerical Simulation study

Shin, H. H. (author), Portela, L. (author), Schaerer, C. E. (author), Mangiavacchi, N. (author)

The dynamics of suspended sediment transport in horizontal open channel flow is analysed using point-particle one-way coupling Direct Numerical Simulations (DNS), with a virtual wall as a simple particle resuspension model. In sediment transport, the bed-load is dominated by the inter-particle interactions, but the suspended sediments are...

journal article 2022

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Controlled Inline Fluid Separation Based on Smart Process Tomography Sensors

Sahovic, Benjamin (author), Atmani, Hanane (author), Sattar, Muhammad Awais A. (author), Martinez Garcia, M. (author), Schleicher, Eckhart (author), Legendre, Dominique (author), Climent, Eric (author), Pedrono, Annaig (author), Portela, L. (author)

Today's mechanical fluid separators in industry are mostly operated without any control to maintain efficient separation for varying inlet conditions. Controlling inline fluid separators, on the other hand, is challenging since the process is very fast and measurements in the multiphase stream are difficult as conventional sensors typically...

journal article 2020

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Electrical resistance tomography for control applications: Quantitative study of the gas-liquid distribution inside a cyclone

Sattar, Muhammad Awais (author), Martinez Garcia, M. (author), Banasiak, Robert (author), Portela, L. (author), Babout, Laurent (author)

Phase separation based centrifugal forces is effective, and thus widely explored by the process industry. In an inline swirl separator, a core of the light phase is formed in the center of the device and captured further downstream. Given the inlet conditions, this gas core created varies in shape and size. To predict the separation behavior...

journal article 2020

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Control of a gas-liquid inline swirl separator based on tomographic measurements

Martinez Garcia, M. (author), Sahovic, B. (author), Sattar, M.A. (author), Atmani, H. (author), Schleicher, E. (author), Hampel, U. (author), Babout, L. (author), Legendre, D. (author), Portela, L. (author)

This text structures the application of Wire-Mesh sensors and Electrical Resistance Tomography in the control of an Inline Swirl Separator. It introduces a mechanistic model of the two-phase flow inside the device, which is linearized around an ideal perfect operation, and implemented in a Model Predictive Controller. The whole text is...

journal article 2020

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Breakup of elongated droplets in microfluidic T-junctions

Haringa, C. (author), De Jong, Conrad (author), Hoang, D. (author), Portela, L. (author), Kleijn, C.R. (author), Kreutzer, M.T. (author), van Steijn, V. (author)

We show experimentally, and explain theoretically, what velocity is needed to break an elongated droplet entering a microfluidic T-junction. Our experiments on short droplets confirm previous experimental and theoretical work that shows that the critical velocity for breakup scales with the inverse of the length of the droplet raised to the...

journal article 2019

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Electrolyte effects on recirculating dense bubbly flow: An experimental study using X-ray imaging

Mandalahalli, M.M. (author), Wagner, E.C. (author), Portela, L. (author), Mudde, R.F. (author)

In this work, the effect of an electrolyte (up to 2 M of NaCl dissolved in water) on a homogeneous dense bubbly flow, in an airlift bubble column, is studied using nonintrusive techniques. X-ray and high-speed imaging are used to investigate the bubble size distribution, the local and the global gas-fraction profiles. The major effect of the...

journal article 2019

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Formation and break-up of rigid agglomerates in turbulent channel and pipe flows

Schutte, K.C.J. (author), Portela, L. (author), Twerda, A. (author), Henkes, R.A.W.M. (author)

We have developed and applied an Eulerian-Lagrangian model for the transport, formation, break-up, deposition and re-entrainment of particle agglomerates. In this paper, we focus on agglomeration and break-up. Simulations were carried out to investigate what changes in the turbulent flow are inflicted by the presence of the agglomerates. Also...

journal article 2018

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The effect of surfactants on upward air-water pipe flow at various inclinations

van Nimwegen, A.T. (author), Portela, L. (author), Henkes, R.A.W.M. (author)

In this work, we extend our previous efforts on the effect of surfactants on air-water flow in a vertical pipe by also considering pipe inclinations between 20° (with respect to horizontal) and vertical. For air-water flow, independent of the inclination, there is a regular annular flow at large gas flow rates, and an irregular churn or slug...

journal article 2016

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Dynamics of droplet breakup in a T-junction

Hoang, D.A. (author), Portela, L.M. (author), Kleijn, C.R. (author), Kreutzer, M.T. (author), Van Steijn, V. (author)

The breakup of droplets due to creeping motion in a confined microchannel geometry is studied using three-dimensional numerical simulations. Analogously to unconfined droplets, there exist two distinct breakup phases: (i) a quasi-steady droplet deformation driven by the externally applied flow; and (ii) a surface-tension-driven three-dimensional...

journal article 2013

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Modeling of low-capillary number segmented flows in microchannels using OpenFOAM

Hoang, D.A. (author), Van Steijn, V. (author), Portela, L.M. (author), Kreutzer, M.T. (author), Kleijn, C.R. (author)

Modeling of low-Capillary number segmented flows in microchannels is important for the design of microfluidic devices. We present numerical validations of microfluidic flow simulations using the volume-of-fluid (VOF) method as implemented in OpenFOAM. Two benchmark cases were investigated to ensure the reliability of OpenFOAM in modeling complex...

conference paper 2012

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Experimental study of particle-driven secondary flow in turbulent pipe flows

Belt, R.J. (author), Daalmans, A.C.L.M. (author), Portela, L.M. (author)

In fully developed single-phase turbulent flow in straight pipes, it is known that mean motions can occur in the plane of the pipe cross-section, when the cross-section is non-circular, or when the wall roughness is non-uniform around the circumference of a circular pipe. This phenomenon is known as secondary flow of the second kind and is...

journal article 2012