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Modelling and Numerical Simulation of Species Transfer in Bubbly Flows using OpenFOAM

Deising, Daniel (2019)
Modelling and Numerical Simulation of Species Transfer in Bubbly Flows using OpenFOAM.
Technische Universität Darmstadt
Ph.D. Thesis, Primary publication

Abstract

The aim of this work is the derivation of an improved closure model for the description of species transfer processes in two-phase gas-liquid flows which in the following, among others, can be used for the numerical simulation of bubble column reactors using a two-fluid model or also to obtain an improved design of fluid reactors. To gain detailed insight into the process, this research is focussed on the Direct Numerical Simulation (DNS) of species transport processes at single rising bubbles (and bubble groups) from the gas into the liquid phase. Due to the special suitability an algebraic Volume-of-Fluid (VoF) method based on the OpenFOAM interFoam solver is utilized. The species transfer is herein modelled employing a new single-field model named Continuous Species Transfer (CST) model which enables a detailed decription of the species transfer process in context of algebraic Volume-of-Fluid methods. A further novelty of the present work is that in contrast to common literature the influence of the bubble shape on the species transfer is considered as an additional influence variable. It is shown that the overall species transfer rate is effectively influenced by two separate mechanisms, leading to a more detailed description of species transfer processes: the generation of new interfacial area due to bubble deformation and the change of the concentration gradient at the bubble interface. The majority of this work is concerned with the comprehensive derivation, verification and validation of the presented numerical model. Modifications to the utilized flow solver are additionally presented and the improvements are quantified.

Item Type: Ph.D. Thesis
Erschienen: 2019
Creators: Deising, Daniel
Type of entry: Primary publication
Title: Modelling and Numerical Simulation of Species Transfer in Bubbly Flows using OpenFOAM
Language: English
Referees: Bothe, Prof. Dieter ; Tropea, Prof. Cameron
Date: 28 February 2019
Place of Publication: Darmstadt
Refereed: 6 February 2019
URL / URN: https://tuprints.ulb.tu-darmstadt.de/8522
Abstract:

The aim of this work is the derivation of an improved closure model for the description of species transfer processes in two-phase gas-liquid flows which in the following, among others, can be used for the numerical simulation of bubble column reactors using a two-fluid model or also to obtain an improved design of fluid reactors. To gain detailed insight into the process, this research is focussed on the Direct Numerical Simulation (DNS) of species transport processes at single rising bubbles (and bubble groups) from the gas into the liquid phase. Due to the special suitability an algebraic Volume-of-Fluid (VoF) method based on the OpenFOAM interFoam solver is utilized. The species transfer is herein modelled employing a new single-field model named Continuous Species Transfer (CST) model which enables a detailed decription of the species transfer process in context of algebraic Volume-of-Fluid methods. A further novelty of the present work is that in contrast to common literature the influence of the bubble shape on the species transfer is considered as an additional influence variable. It is shown that the overall species transfer rate is effectively influenced by two separate mechanisms, leading to a more detailed description of species transfer processes: the generation of new interfacial area due to bubble deformation and the change of the concentration gradient at the bubble interface. The majority of this work is concerned with the comprehensive derivation, verification and validation of the presented numerical model. Modifications to the utilized flow solver are additionally presented and the improvements are quantified.

Alternative Abstract:
Alternative abstract Language

Das Ziel dieser Arbeit ist die Herleitung eines verbesserten Schliessungsmodells zur Beschreibung von Stofftransportprozessen in Zwei-Phasen Gas-Flüssig Strömungen, welches im weiteren unter anderem zur Simulation von Blasensäulenreaktoren mittels Zwei-Fluid Modell oder auch zur verbesserten Auslegung von Strömungsreaktoren genutzt werden kann. Um detailierte Einblicke in den Prozess zu gewinnen, fokussiert sich diese Forschungsarbeit auf die Direkte Numerische Simulation (DNS) von Stofftransportprozessen an aufsteigenden Einzelblasen (und Blasengruppen) von der Gas- in die Flüssigphase. Aufgrund der besonderen Eignung für das vorliegende Problem, wird hierzu ein algebraisches Volume-of-Fluid (VoF) Verfahren basierend auf dem OpenFOAM ® interFoam Löser verwendet. Der Stofftransport wird mittels eines neuen Ein-Gleichungs-Modells Namens Continuous Species Transfer (CST) Modell abgebildet, welches eine genaue Beschreibung des Stoffübergangs im Kontext der algebraischen Volume-of-Fluid Methode erlaubt. Eine weitere Neuheit der vorliegenden Arbeit ist, dass im Gegensatz zur gängigen Fachliteratur der Einfluss der Blasenform auf den Stoffübergang als weitere Einflussgrösse berücksichtigt wird. Es wird gezeigt, dass eine detailierte Beschreibung des Stofftransportprozesses nur durch die Betrachtung zweier getrennter Mechanismen möglich ist: der Generierung neuer Grenzfläche durch Verformung der Grenzschicht und der Änderung der Konzentrationsgradienten an der Blasengrenzfläche. Der Großteil dieser Arbeit befasst sich mit der umfassenden Herleitung, Verifizierung und Validierung des numerischen Modells. Änderungen an dem verwendeten Strömungslöser werden ebenfalls vorgestellt und die Verbesserungen quantifiziert.

German
URN: urn:nbn:de:tuda-tuprints-85227
Classification DDC: 600 Technology, medicine, applied sciences > 620 Engineering and machine engineering
Divisions: 16 Department of Mechanical Engineering
04 Department of Mathematics
04 Department of Mathematics > Analysis
04 Department of Mathematics > Analysis > Mathematical Modeling and Analysis
04 Department of Mathematics > Mathematical Modelling and Analysis
Date Deposited: 21 Apr 2019 19:55
Last Modified: 07 Feb 2024 11:55
PPN:
Referees: Bothe, Prof. Dieter ; Tropea, Prof. Cameron
Refereed / Verteidigung / mdl. Prüfung: 6 February 2019
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