IMS: Christian Weiland

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Christian Weiland, M.Sc.

Eissendorfer Str. 40

Building N, Room 1.082

21073 Hamburg

Phone +49 40 42878 - 4644

Mail Christian Weiland

Research

For the optimisation of stirred tank reactors (STR), simulative studies are conducted. The focus is on the determination of the mixing efficiency and the identification of compartments in such vessels. The simulations are carried out utilising the Lattice Boltzmann Method. The further analyses are done with Lagrangian methods, namely the calculation of the arising Finite Time Lyapunov Exponent, the occurring Finite Time Lyapunov Mixing Intensity and the estimation of the network in the observed vessels which directly delivers knowledge about the positions of compartments.

The information retrieved from the Lagrangian analyses is processed further to develop a model describing the observed STR. Additionally, the information concerning the arising deformation of fluid elements, quantified by the Finite Time Lyapunov Exponent, is used for the modelling of multiphase phenomena such as bubble breakup.

Education

Undergraduate and Graduate Teaching Assistant

Fundamentals of Fluid Mechanics (Fluid Mechanics I)
Fluid Mechanics in Process Engineering (Fluid Mechanics II)
Process Design Project (Projektierungskurs), Winter term 2020/2021

Supervised Theses

Computational Study of the Influence of Stirrer Configurations on the Lagrangian Mixing in a Stirred Tank Rector (working title), Yvonne Schade, Master’s Thesis, ongoing
Numerische Untersuchung des Einflusses ausgewählter Rührervariationen auf das Strömungsverhalten innerhalb eines Rührkesselreaktors, Boran Salli, Bachelor’s Thesis (in supervision coorperation with Ingrid Haase, M.Sc.), ongoing
Comparison of the Lattice Boltzmann Method and Finite Volume Method in Continuously Operated Static Mixers - a CFD Benchmark Study, Roman Neubauer, Master's Thesis (in supervision coorperation with Torben Frey, M.Sc.), April 2023
Auslegung und Bau eines Wassermühlrades im Labormaßstab zur Ermittlung der abgegeben Leistung im Originalmaßstab unter Berücksichtigung ausgewählter dimensionsloser Kennzahlen (working title), Jarik Koenig, Project Work (in supervision coorperation with Felix Kexel, M.Sc.), ongoing
Direkte Numerische Simulation des Grenzflächen-Stofftransports in Blasenströmungen mithilfe einer VOF-Methode, Roberto Flores Cavero, Master's Thesis (in supervision coorperation with PD Dr.-Ing habil. Yan Jin), July 2022
Untersuchung von Transportbarrieren innerhalb eines kontinuierlichen Rührkesselreaktors unter Verwendung dreidimensionaler Lagrangescher Kohärenter Strukturen, Eike Steuwe, Master's Thesis (in supervision coorperation with Prof. Dr. Alexandra von Kameke), May 2022
Ermittlung der Leistungsabgabe eines Wassermühlenrades unter Verwendung numerischer Strömungssimulation, Alexander Hanke, Project work, April 2022
Charakterisierung der Totzeitverteilung in Rührkesselreaktoren mittels numerischer Strömungssimulation mit der Lattice-Boltzmann Methode, Mustafa Salli, Bachelor's Thesis, March 2022
Mehrzieloptimierung einer durchströmten offenen Struktur unter Anwendung des diskreten Adjungiertenverfahrens mittels numerischer Strömungssimulation, Mona Abbas Sayed Omar, Master's Thesis (in supervision coorperation with Claas Spille, M.Sc.), January 2022
Nichtinvasive Bestimmung des portosystemischen Druckgradienten nach TIPS-Implantation: Vergleich von stationären und transienten numerischen Strömungssimulationen, Muhammad Ismahil, Master's Thesis (in supervision coorperation with Dr.-Ing. Marko Hoffmann and close coorperation with Dr. med. Christoph Riedel (UKE)), December 2021
Analyse von Einflussparametern auf den portosystemischen Druckgradienten nach TIPS-Implantation mittels numerischer Strömungssimulation, Eleonora Abu Rashed, Master's Thesis (in supervision coorperation with Dr.-Ing. Marko Hoffmann and close coorperation with Dr. med. Christoph Riedel (UKE)), May 2021
Geometrieoptimierung unter Nutzung numerischer Simulation mittels Verwendung des ANSYS Adjoint Solvers, Mona Abbas Sayed Omar, Project Work (in supervision coorperation with Claas Spille, M.Sc.), March 2021
Numerische Simulation der Fluiddynamik unter Berücksichtigung der Mischcharakteristik eines nicht-newtonschen Fluides innerhalb einer industriellen Mischapparatur, Simon Abraha, Master's Thesis, July 2020
Bewertung einer neuen Methode zur nichtinvasiven Messung von dynamischen Temperaturverläufen mittels numerischer Strömungssimulation, Hanno Hagenström, Master's Thesis, Dezember 2019
Prediction of the Mass Transfer Coefficient Based on the Eddy Cell Model for an Aerated Stirred Tank Reactor under Multiple Operating Conditions, Hendrick Jansen, Master's Thesis, November 2019

Oral and Poster Presentations

Oral Presentations

Weiland, C.; Steuwe, E.; von Kameke, A.; Hoffmann, M.; Schlüter, M.:“ Identification of Compartments in Stirred Tank Reactors by Analysing Lagrangian Coherent Structures From Velocity Fields Derived by the Lattice-Boltzmann-Method”, 11^th International Conference of Multiphase Flow 2023, Kobe, oral presentation
Weiland, C.; Hofmann, S.; Fitschen, J.; von Kameke, A.; Hoffmann, M.; Schlüter, M.: "Numerische Simulation Lagrangescher Partikeltrajektorien und Charakterisierung des Partikelfolgevermögens in einem 3 L Rührkesselreaktor", ProcessNet Jahrestreffen CFD, Mischen und Agglomeration 2022, Leipzig, oral presentation
Hofmann, S.; Weiland, C.; Fitschen, J.; von Kameke, A.; Hoffmann, M.; Schlüter, M.: "Vergleich von experimentellen und numerischen Untersuchungen zur Abschätzung des Folgevermögens verschiedener Lagrange’scher Partikel in der Bioreaktorströmung", ProcessNet Jahrestreffen CFD, Mischen und Agglomeration 2022, Leipzig, oral presentation

Poster Presentations

Hofmann, S.; Weiland, C.; GopalSingh, P.; Kamp, M.; Fitschen, J.; v. Kameke, A.; Hoffmann, M.; Schlüter, M.: "Experimental and numerical determination of lifelines in a 3 L, 200 L and 15000 L stirred tank reactor to estimate the flow-following capability of Lagrangian Sensor Particles", MIXING XXVII, North American Mixing Forum (NAMF), Online Conference 2022, virtual poster presentation
Weiland, C.; Fitschen, J.; Hoffmann, M.; Schlüter, M.:"Numerical Simulation and Validation of the Bubble Size Distribution in an Aerated Stirred Tank Reactor", ProcessNet Jahrestreffen Mehrphasenströmungen & CFD 2021, virtual poster presentation
Weiland, C.; Hoffmann, M.; Schlüter, M.: "Numerical Simulation of the Mixing Time and Pathlines of Lagrangian Tracer Particles in a Stirred Tank Reactor", Hamburg-Bochumer Mehrphasensymposium, 2020, virtual poster presentation

Publications

[187294]

Title: Direct Numerical Simulation of Bubble Collision, Bounce and Coalescence in Bubble-Induced Turbulence.

Written by: Jin, Y.; Weiland, C.; Hoffmann, M.; Schlüter, M.

in: <em>Chemical Engineering Science</em>. (2023).

Volume: <strong>284</strong>. Number:

on pages: 119502

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DOI: https://doi.org/10.1016/j.ces.2023.119502

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Abstract: A direct numerical simulation study has been carried out to better understand the dynamics of deformable bubbles in bubble-induced turbulence. A mathematical model for bubble collision, bounce and coalescence is developed based on the Volume-of-Fluid (VoF) method. A surface-tension-holding film thickness δc is introduced to determine whether the bubbles will coalesce or bounce after collision. Bubbly flows with the gas volume fractions αg=5.6% (low), 11.2% (medium) and 22.1% (high) are considered in the study. The DNS results show that the dissipation of turbulent kinetic energy in the cases under consideration takes place when the wavenumber κ is smaller than twice the wavenumber for the bubble diameter 2κd. The bubble-induced turbulence is anisotropic at the length scales close to the bubble diameter due to the elongated turbulent structures in the bubble-rising direction. The bubbles collide intensively with each other when they are in a cluster surrounded by the liquid with low pressure. Parallel clustering of bubbles is found when the gas volume fraction has a low or medium value. Three-dimensional clustering is found when the bubbles are densely populated. Two different mechanisms of bubble collision have been identified from the DNS results, termed parallel collision and vertical collision. Parallel collision is often observed when bubbles are sparsely populated. In a parallel collision, the relative velocity of the bubbles slows down as two bubbles approach each other due to the jet flow between them, while the relative velocity increases sharply after the bounce. In a vertical collision, by contrast, the relative velocity of bubbles accelerates as two bubbles approach each other, while it slows down during the collision. Vertical collisions occur when the bubbles are more densely populated. The numerical results also show the significant effects of δc on bubble coalescence.

TU Hamburg

Institute of Multiphase Flows

Eißendorfer Straße 38

21073 Hamburg

E-mail : info@ims-tuhh.de

Phone : +49 (0) 40 42878 - 3252

Fax : +49 (0) 40 42731 - 4609

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