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Large-Eddy Simulations of microcarrier exposure to potentially damaging eddies inside mini-bioreactors Collignon, Marie-Laure ; ; Calvo, Sébastien et al in Biochemical Engineering Journal (in press) Mechanically stirred vessels equipped with rotating impellers generate heterogeneous transitional or turbulent flows. However, some cells as animal or human mesenchymal stem cells (hMSC) adhered on ... [more ▼] Mechanically stirred vessels equipped with rotating impellers generate heterogeneous transitional or turbulent flows. However, some cells as animal or human mesenchymal stem cells (hMSC) adhered on microcarriers, are reputed sensitive to hydromechanical stresses arising from stirring. Many publications, especially using Computational Fluid Dynamics, characterize spatial fields of velocity and turbulence inside bioreactors but the exposure frequency to these stresses is never taken into account in the case of animal cell culture bioreactor description. To fill this gap, this study used both CFD Reynolds-Averaged and Large-Eddy Simulations to characterize the hydrodynamics inside 250 mL mini-bioreactors, which is a relevant volume for hMSC cultures. Five impeller geometries were studied. From the velocity and turbulence fields calculated, an energy dissipation/circulation function, related to both frequency and intensity of potentially damaging hydrodynamic events for the cells, was determined for various operating conditions. Based on the simulation results, the marine propeller operating in up-pumping mode seems to be the most adapted condition, since it exhibits a low frequency of exposure to an acceptable intensity of the turbulent dissipation rate. From a general point of view, the new methodology proposed should be used in the future to screen the most adapted bioreactor geometry to biological constraints. [less ▲] Detailed reference viewed: 32 (10 ULg)Euler–Lagrange approach to model heterogeneities in stirred tank bioreactors – Comparison to experimental flow characterization and particle tracking Delafosse, Angélique ; Calvo, Sébastien ; Collignon, Marie-Laure et al in Chemical Engineering Science (2015), 134 The aim of this work is the validation of an Euler–Lagrange modeling approach coupling a CFD-based compartment model (Eulerian approach) and a stochastic model based on a Continuous-Time Markov Chain ... [more ▼] The aim of this work is the validation of an Euler–Lagrange modeling approach coupling a CFD-based compartment model (Eulerian approach) and a stochastic model based on a Continuous-Time Markov Chain (Lagrangian approach). The turbulent flow structure and the mixing process in a bioreactor stirred by an axial Mixel TT impeller is characterized by PIV and tracer experiments. Comparison between experimental and numerical data shows that the CFD-based compartment model is able to reproduce accurately the spatial heterogeneities inside the bioreactor. The trajectory of a small tracer particle which perfectly follows the fluid flow is measured by optical trajectography. It is then simulated by a stochastic model which is either based on an homogeneous or on an inhomogeneous Continuous Time Markov Chain (CTMC). Comparison of residence and circulation time distributions in three zones defined inside the bioreactor shows that the inhomogeneous CTMC model predicts with an excellent accuracy the particle trajectories inside the bioreactor. The modeling approach proposed here could be an useful tool to design scale-down bioreactors in order to reproduce at lab-scale the stress levels encountered in large-scale production bioreactors and to characterize and compare different bioreactor configurations. [less ▲] Detailed reference viewed: 20 (2 ULg)Euler–Lagrange approach to model heterogeneities in stirred tank bioreactors – Comparison to experimental flow characterization and particle tracking Delafosse, Angélique ; Calvo, Sébastien ; Collignon, Marie-Laure et al in Chemical Engineering Science (2015), 134 The aim of this work is the validation of an Euler–Lagrange modeling approach coupling a CFD-based compartment model (Eulerian approach) and a stochastic model based on a Continuous-Time Markov Chain ... [more ▼] The aim of this work is the validation of an Euler–Lagrange modeling approach coupling a CFD-based compartment model (Eulerian approach) and a stochastic model based on a Continuous-Time Markov Chain (Lagrangian approach). The turbulent flow structure and the mixing process in a bioreactor stirred by an axial Mixel TT impeller is characterized by PIV and tracer experiments. Comparison between experimental and numerical data shows that the CFD-based compartment model is able to reproduce accurately the spatial heterogeneities inside the bioreactor. The trajectory of a small tracer particle which perfectly follows the fluid flow is measured by optical trajectography. It is then simulated by a stochastic model which is either based on an homogeneous or on an inhomogeneous Continuous Time Markov Chain (CTMC). Comparison of residence and circulation time distributions in three zones defined inside the bioreactor shows that the inhomogeneous CTMC model predicts with an excellent accuracy the particle trajectories inside the bioreactor. The modeling approach proposed here could be an useful tool to design scale-down bioreactors in order to reproduce at lab-scale the stress levels encountered in large-scale production bioreactors and to characterize and compare different bioreactor configurations. [less ▲] Detailed reference viewed: 5 (0 ULg)Surface aeration in baffled stirred tanks: hydrodynamics, mixing and mass transfer characteristics de Lamotte, Anne ; Delafosse, Angélique ; Calvo, Sébastien et al Poster (2015, September) Biotechnological and chemical processes often need a supply of gas for acceptable product formation. In some applications - where either gas requirements/reactor volumes are relatively low, or bubbles are ... [more ▼] Biotechnological and chemical processes often need a supply of gas for acceptable product formation. In some applications - where either gas requirements/reactor volumes are relatively low, or bubbles are undesirable - aeration through the liquid free-surface is enough to meet the demand. In case of sparged stirred tanks, aeration through the liquid free-surface is a factor to be determined when scaling-up /down processes. Gas-liquid transfer is strongly influenced by the hydrodynamic conditions. Two phenomena, occurring at different scales, can be coupled in order to explain mass transfer : (i) circulation (macroscale) and (ii) mixing/homogenization (microscale). Mixing/homogenization takes into consideration the small eddies responsible for the rippled liquid free-surface and for the concentration gradients surrounding it. Circulation determines the fluid path across the reactor as well as its contribution of the surface aeration and leads to periodic and local deformation of the liquid free-surface. Circulation also accounts for the design of the reactor, where the scaling problems are focused. The objective of this work is to develop an experimental approach able to fully (global and local quantities) characterize a chosen agitation configuration in terms of hydrodynamics, mixing and transfer, in order to assess the capability of computational methods to predict gas-liquid mass transfer due to aeration through the liquid free-surface. [less ▲] Detailed reference viewed: 42 (11 ULg)VALIDATION OF AN EULER-LAGRANGE COMPARTMENT MODEL FOR THE DESIGN OF SCALE-DOWN BIOREACTOR USED IN ANIMAL CELL CULTURES Delafosse, Angélique ; Calvo, Sébastien ; Collignon, Marie-Laure et al in Proceeding of the 15th European Conference on Mixing (2015, June) Detailed reference viewed: 5 (1 ULg)Hydrodynamics, mixing and mass transfer in baffled stirred tanks de Lamotte, Anne ; Delafosse, Angélique ; Calvo, Sébastien et al Conference (2015, June) The present work presents CFD simulations of hydrodynamics, mixing and mass transfer in a surface-aerated baffled stirred tank. The modelling of the multiphase flow is realized via an Euler-Euler approach ... [more ▼] The present work presents CFD simulations of hydrodynamics, mixing and mass transfer in a surface-aerated baffled stirred tank. The modelling of the multiphase flow is realized via an Euler-Euler approach. Three closure models are tested for the resolution of the RANS equations. When fully-developed flow field is reached, gas-liquid transfer is implemented with a local mass transfer coefficient estimated by the eddy cell model, and the temporal evolution of dissolved gas concentration is predicted.Hydrodynamic and mixing quantities as well as mass transfer parameters for the different turbulence models are compared with experimental data available for the same geometrical and operating features. A critical analysis of the prediction results allow to assess the models capabilities and to highlight the possible critical issues of the simulations. [less ▲] Detailed reference viewed: 75 (19 ULg)HYDRODYNAMICS IN A DISPOSABLE RECTANGULAR PARALLELEPIPED STIRRED BIOREACTOR WITH ELLIPTIC PENDULUM MOTION PADDLE Collignon, Marie-Laure ; ; Delafosse, Angélique et al in Biochemical Engineering Journal (2015), 93 Stainless steel bioreactors increasingly fall behind to their disposable counterparts in pharma research as they do not require cleaning or sterilization. This led company ATMI LifeSciences to develop the ... [more ▼] Stainless steel bioreactors increasingly fall behind to their disposable counterparts in pharma research as they do not require cleaning or sterilization. This led company ATMI LifeSciences to develop the “Nucleo™”. Original in design, this disposable bioreactor comprises a rectangular parallelepiped plastic bag stirred by a paddle revolving in elliptic pendulum motion. Studies covering this bioreactor showed good homogeneity of culture medium as well as good productivity for animal cell cultures. To further explain these good performances, the flow inside the “Nucleo™” had to be resolved. This paper focuses on the mean flow description, computed from stereo-PIV measurements performed in 20 verticals covering the whole volume of a 50 dm3 Nucleo™ bioreactor. As the flow is already turbulent in the chosen agitation conditions, its dimensionless mean velocity field does not vary with the paddle rotational speed. Mean flow pattern exhibits an axial symmetry – same flow is observed in opposite quarters of the tank – and can be described as a three-dimensional helix coiled on itself to form a distorted horizontal torus which covers the whole tank volume. Mean velocity value is on average doubled in the cone swept by the paddle, and its two horizontal components are twice higher than its vertical ones. However, mean velocity remains significant everywhere and, in particular, no stagnant area is observed in tank corners. Our results thus confirm previous studies observations. [less ▲] Detailed reference viewed: 65 (19 ULg)CFD Comparison of hydrodynamics between BIOSTAT® Cultibag STR and standard Stirred Cell Culture Bioreactors Calvo, Sébastien ; Delafosse, Angélique ; Crine, Michel et al Poster (2014, September 10) Single-use bioreactors have been increasingly used for animal cell cultures on microcarriers in screening experiments. Because of their manufacturing process, the shape of these kinds of vessels such as ... [more ▼] Single-use bioreactors have been increasingly used for animal cell cultures on microcarriers in screening experiments. Because of their manufacturing process, the shape of these kinds of vessels such as the BIOSTAT® Cultibag STR one, is limited. For example, technical constraints on weld seams limit angles to 30° and no baffle may be installed. The shape of standard re-usable vessels may thus not be exactly reproduced and the flow structure may thus significantly differs from the flow structure in standard bioreactors. [less ▲] Detailed reference viewed: 53 (11 ULg)CFD-based Compartment model for description of mixing in bioreactors Delafosse, Angélique ; Calvo, Sébastien ; Collignon, Marie-Laure et al in Chemical Engineering Science (2014), 106 In most bioprocesses, it is fundamental to accurately predict the hydrodynamics behavior of bioreactors of different size and its interaction with the biological reaction. Computational Fluid Dynamics can ... [more ▼] In most bioprocesses, it is fundamental to accurately predict the hydrodynamics behavior of bioreactors of different size and its interaction with the biological reaction. Computational Fluid Dynamics can provide detailed modeling about hydrodynamics and mixing. However, it is computationally intensive, especially when reactions are taken into account. Another way to predict hydrodynamics is the use of “Compartment” or “Network-of-zones” model which are much less demanding in computation time than CFD. However, compartments and fluxes between them are often defined by considering global quantities not representative of the flow complexity. To overcome the limitations of these two methods, a solution is to combine compartment modeling and CFD simulations. The aim of this study is to propose a compartment model where the flow rates between two adjacent compartments are easily computed from the velocity fields obtained by CFD. The mixing evolution predicted by the CFD-based compartment model have been then compared with mixing experiment results. Unlike a CFD mixing simulation and a classical compartment model, the CFD-based compartment model proposed in this work reproduces with a good accuracy the spatial distribution of concentrations during the mixing process and this, without any adjustable parameters. [less ▲] Detailed reference viewed: 88 (27 ULg)Caractérisation expérimentale et modélisation des conditions de mise en suspension homogène d’un solide dans une cuve agitée industrielle Calvo, Sébastien ; Delafosse, Angélique ; Collignon, Marie-Laure et al in Récents Progrès en Génie des Procédés (Cd-ROM) (2013, September) In this work, we study the conditions needed to reach homogeneous distribution of solid particles of aluminium salts in water inside a GRC bottom shape stirred tank of 70L equipped with Pfaudler RCI type ... [more ▼] In this work, we study the conditions needed to reach homogeneous distribution of solid particles of aluminium salts in water inside a GRC bottom shape stirred tank of 70L equipped with Pfaudler RCI type impeller and three equispaced vertical baffles. The aim of the present study is to develop a CFD model describing the quality of particle distribution at the industrial scale. This model, validated with experimental data, is afterward used to developed scale-up and scale-down correlation to predict the minimum impeller speed needed to reach homogeneous solid distribution Nhs. The commercial CFD tool Fluent 14 is used to model the fluid flow and the solid particle distribution in the tank. The 3D geometry of the tank and the associated mesh are realized respectively by Ansys 14 DesignModeler and Meshing. The Sliding-Mesh approach is used to take into account the impeller motion. Assuming that only the continuous phase is present, the fluid flow dynamics may be simulated independently using the wellknown k-ε turbulence model. The behaviour of the liquid-solid mixture is then described implementing the Eulerian Mixture model. Liquid velocity fields simulated by CFD have been validated by comparison with PIV (Particle Image Velocimetry) measurements. Computed Nhs is well compared to experimental data obtained with a nephelometric probe. Results obtained at different scales allowed correlating Nhs and volumetric power consumption. [less ▲] Detailed reference viewed: 61 (8 ULg)Experimental characterisation and modelling of homogeneous solid suspension in an industrial stirred tank Calvo, Sébastien ; Delafosse, Angélique ; Collignon, Marie-Laure et al in Advances in Mechanical Engineering (2013), Volume 2013 In this work, we study the conditions needed to reach homogeneous distribution of aluminium salts particles in water inside a torispherical bottom shaped stirred tank of 70 L equipped with a Pfaudler RCI ... [more ▼] In this work, we study the conditions needed to reach homogeneous distribution of aluminium salts particles in water inside a torispherical bottom shaped stirred tank of 70 L equipped with a Pfaudler RCI type impeller and three equispaced vertical baffles. The aim of the present study is to develop a CFD model describing the quality of particle distribution in industrial scale tanks. This model, validated with experimental data, is used afterwards to develop scale-up and scale-down correlations to predict the minimum impeller speed needed to reach homogeneous solid distribution Nhs.The commercial CFD software Fluent 14 is used to model the fluid flow and the solid particle distribution in the tank. Sliding Mesh approach is used to take the impeller motion into account. Assuming that the discrete solid phase has no influence on the continuous liquid phase behaviour, the fluid flow dynamics is simulated independently using the well-known k-ε turbulence model. The liquid-solid mixture behaviour is then described by implementing the Eulerian Mixture model. Computed liquid velocity fields are validated by comparison with PIV measurements. ComputedNhs were found to be in good agreement with experimental measurements. Results fromdifferent scales allowed correlating Nhs values to the volumetric power consumption. [less ▲] Detailed reference viewed: 64 (15 ULg)CFD Modelisation of homogeneous distribution of solid particles in a stirred tank Calvo, Sébastien ; Delafosse, Angélique ; Collignon, Marie-Laure et al Poster (2013, April 24) In this work, we study the conditions needed to reach homogeneous distribution of solid particles of aluminium salts in water inside a torospherical bottom shaped stirred tank reactor of 70L equipped with ... [more ▼] In this work, we study the conditions needed to reach homogeneous distribution of solid particles of aluminium salts in water inside a torospherical bottom shaped stirred tank reactor of 70L equipped with a Pfaudler RCI type impeller and three equi-spaced vertical baffles. The aim of the present study is to develop a CFD model describing the quality of particle distribution in industrial scale tanks. This model, validated with experimental data, is afterward used to developed scale-up and scale-down correlations to predict the minimum impeller speed needed to reach homogeneous solid distribution Nhs. The commercial CFD software Fluent 14 is used to model the fluid flow and the solid particle distribution in the tank. The 3D geometry of the tank and the associated mesh are respectively realized by Ansys 14 DesignModeler and Meshing. The Sliding-Mesh approach is used to take the impeller motion into account. Assuming that the discrete solid phase has no influence on the continuous liquid phase behaviour, the fluid flow dynamics may be simulated independently using the well-known k-ε turbulence model. The behaviour of the liquid-solid mixture is then described by implementing the Eulerian Mixture model. Liquid velocity fields simulated by CFD have been validated by comparison with PIV (Particle Image Velocimetry) measurements. Computed values of Nhs are compared with good agreement to experimental data obtained with a nephelometric probe. Results obtained at different scales allowed correlating the Nhs value to the volumetric power consumption. [less ▲] Detailed reference viewed: 66 (9 ULg)Simulation d’un écoulement de gaz dans un empilage structuré par la méthode des réseaux de Boltzmann ; Calvo, Sébastien ; Crine, Michel et al in SFGP (Ed.) Récents Progrès en Génie des Procédés - N° 101 - Des procédés au service du produit au coeur de l'Europe - Actes du XIIIème Congrès de la société Française de Génie des Procédés - Du 29 Nov. au 1er Décembre 2011 - Lille Grand Palais, FRANCE (2011, November 29) Numerical simulations of gas flow between two sheets of plastic MellapakTM 250 Y are performed using Lattice Boltzmann methods in laminar and turbulent regimes. Results are compared with experimental ... [more ▼] Numerical simulations of gas flow between two sheets of plastic MellapakTM 250 Y are performed using Lattice Boltzmann methods in laminar and turbulent regimes. Results are compared with experimental measurements and with known correlations. They are also compared with simulations using a classical CFD code. In all cases, the agreement is very good. An original method based on the simulated axial velocity profiles is proposed to caracterize the gas flow regime. [less ▲] Detailed reference viewed: 31 (5 ULg)Gas Flow Simulations in a Structured Packing by Lattice Boltzmann Method ; Calvo, Sébastien ; Crine, Michel et al Conference (2011, November 15) Numerical simulations of gas flow between two sheets of plastic MellapakTM 250 Y are performed using Lattice Boltzmann methods in laminar and turbulent regimes. Results are compared with experimental ... [more ▼] Numerical simulations of gas flow between two sheets of plastic MellapakTM 250 Y are performed using Lattice Boltzmann methods in laminar and turbulent regimes. Results are compared with experimental measurements and with known correlations. They are also compared with simulations using a classical CFD code. In all cases, the agreement is very good. [less ▲] Detailed reference viewed: 45 (7 ULg)Gas Flow Simulations in a Structured Packing by Lattice Boltzmann Method ; Calvo, Sébastien ; Crine, Michel et al in Chemical Engineering Science (2011), 66 Numerical simulations of gas flow between two sheets of plastic MellapakTM 250 Y are performed using Lattice Boltzmann methods in laminar and turbulent regimes. Results are compared with experimental ... [more ▼] Numerical simulations of gas flow between two sheets of plastic MellapakTM 250 Y are performed using Lattice Boltzmann methods in laminar and turbulent regimes. Results are compared with experimental measurements and with known correlations. They are also compared with simulations using a classical CFD code. In all cases, the agreement is very good. [less ▲] Detailed reference viewed: 152 (11 ULg)Caractérisation de l'hydrodynamique des écoulements gaz-liquide à contre-courant dans une colonne rectangulaire à empilage Calvo, Sébastien Doctoral thesis (2010) La recherche réalisée dans le cadre de cette thèse consiste à développer des électrodes positives pour les accumulateurs (ou "batteries") au lithium sous formes de films minces de quelques centaines de ... [more ▼] La recherche réalisée dans le cadre de cette thèse consiste à développer des électrodes positives pour les accumulateurs (ou "batteries") au lithium sous formes de films minces de quelques centaines de nanomètres d'épaisseur. Afin de stocker un maximum d'énergie dans le volume réduit d'un accumulateur au lithium miniature, une architecture mésoporeuse (dont le diamètre des pores est compris entre 2 et 50 nm), permettant d’augmenter la surface spécifique du matériau, a été réalisée au sein des films. Deux méthodes de soft templating ont été utilisées dans cette thèse. Ces méthodes consistent à ajouter à la solution de précurseurs inorganiques un copolymère amphiphile formateur de micelles, dont l'élimination ultérieure par traitement thermique permet d'obtenir des films contenant des pores dont la dimension varie selon le copolymère utilisé. Dans la perspective du développement d'une électrode pour accumulateur au lithium, deux stratégies sont possibles : (i) la préparation d'un film mésoporeux de l'oxyde non lithié, suivie d'une insertion du lithium par voie électrochimique, ou (ii) la préparation directe d'un film mésoporeux de l'oxyde lithié. Ces deux voies ont été comparées et l’influence du lithium sur la synthèse des films minces mésoporeux par soft templating a donc pu être étudiée. En termes de compositions ciblées, les oxydes de vanadium et de lithium (Li-V-O), tels que LiV3O8 ou LiV2O5, constituent des objectifs évidents en raison de leurs performances électrochimiques reconnues. Etant donné le caractère a priori délicat de la condensation des réseaux à base d'oxyde de vanadium, d'autres systèmes ont également été abordés dans le cadre de la thèse, à savoir Li-V-Nb-O, Li-Nb-O et Li-Ti-O. [less ▲] Detailed reference viewed: 36 (13 ULg)Comparison of hydrodynamic parameters obtained by 2D measurements in a flat rectangular column with X-ray radiography and data from literature on 3D columns Calvo, Sébastien ; Beugre, Djomice Antoine ; Crine, Michel et al Poster (2010) Hydrodynamic tests are performed in a flat rectangular column packed with two sheets of Mellapak 250 Y (Sulzer structured packing). Measurements are realized with a single phase liquid flow as well as ... [more ▼] Hydrodynamic tests are performed in a flat rectangular column packed with two sheets of Mellapak 250 Y (Sulzer structured packing). Measurements are realized with a single phase liquid flow as well as with a gas-liquid counter-current flow. Hydrodynamic parameters are compared to experimental results obtained in 3D columns found in the literature, as well as to literature model predictions and to values computed using an in-house Lattice Boltzmann CFD simulation code. [less ▲] Detailed reference viewed: 51 (15 ULg)Lattice Boltzmann 3D flow simulations on a metallic foam Beugre, Djomice Antoine ; Calvo, Sébastien ; Dethier, Gérard et al in Journal of Computational & Applied Mathematics (2009) Detailed reference viewed: 292 (32 ULg)Phase distribution measurements in metallic foam packing using X-ray radiography and micro-tomography Calvo, Sébastien ; Beugre, Djomice Antoine ; Crine, Michel et al in Chemical Engineering & Processing (2009), 48(5), 1030-1039 Some structural and hydrodynamic properties of RCM-NCX-1116, a Ni-Cr metallic foam packing manufactured by Recemat International B.V (The Netherlands) are investigated using X-ray radiography and X-ray ... [more ▼] Some structural and hydrodynamic properties of RCM-NCX-1116, a Ni-Cr metallic foam packing manufactured by Recemat International B.V (The Netherlands) are investigated using X-ray radiography and X-ray micro-tomography. Local values of porosity and pore diameters are measured on a foam sample 3D image obtained with a Skyscan-1172 high-resolution desk-top micro-CT system operated at 100 kV. Structural parameters computed on tomography images agree well with manufacturer data. Hydrodynamic tests are performed in a flat rectangular column packed with a sheet of metallic foam packing. Measurements are realized with a single-phase flow of liquid as well as with a counter-current flow of gas and liquid. Dynamic and static liquid holdup distributions and liquid radial spreading coefficient are measured on 2D radiographic images of the bed obtained with the high energy large scale ULG 420 kV scanner operated in the radiographic mode at 420 kV. Pressure drop measurements are successfully compared to experimental results reported in literature, as well as to the literature model predictions and to values computed using an in-house Lattice Boltzmann CFD simulation code. (C) 2009 Elsevier B.V. All rights reserved. [less ▲] Detailed reference viewed: 107 (17 ULg)Mesure de la distribution des phases dans une mousse métallique par radiographie et micro-tomographie à rayons X Toye, Dominique ; Aferka, Saïd ; Calvo, Sébastien et al in Récents Progrès en Génie des Procédés - N°95 - Actes des 5èmes Journées francophones sur les réacteurs gaz-liquide et gaz-liquide-solide, 12-15 juin 2007, Carry-le-Rouet, France (2007, June) Detailed reference viewed: 44 (12 ULg) |
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