Cai, Xuan

Deutschmann, Olaf

Marschall, Holger

Wörner, Martin

English

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Direct Numerical Simulations of Gas-liquid Flows in Subdomains of Structured Innovative Multiphase Chemical reactors

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KIT – University of the State of Baden-Wuerttemberg and National Research Center of the Helmholtz Association www.kit.eduJahrestreffen der ProcessNet-Fachgruppen Computational Fluid Dynamics, 29.02 – 02.03, 2016, BingenDirect Numerical Simulations of Gas-liquid Flows in Subdomains of Structured Innovative Multiphase Chemical reactors  Xuan Cai1, Martin Wörner1, Holger Marschall2, Olaf Deutschmann11Karlsruhe Institute of Technology 2Technische Universität Darmstadt2OutlineMotivation & introductionPhase field method and phaseFieldFoam in OpenFOAMSimulations of single droplet wetting dynamics Interface-resolving simulations of two-phase flows in foam structureSimulations of rising bubble in periodic open-cell structureSummary & outlooksJuly 01, 20153MotivationUnderstanding hydrodynamic interaction of gas-liquid flows with solid surface Local fluid dynamics features motion of three-phase contact line Liquid GasSolidClassical paradox between:•motion of contact line •no-slip boundary condition  Volume fraction equation in VOF:on wallMulitphase chemical reactor with structured packingsInternal StructureMicrofluidic deviceCredit: WheelerLotus effectCredit: Wijesena4Single-field Navier-Stokes equation: Phase field (C ) as phase indictorSmooth transition from -1 to 1 → diffuse interfaceC15.06.15C = -1C =1tanh2xCPhase Field MethodCahn-Hilliard equations for phase field evolution describes motion of contact line!Wetting boundary condition for static contact angleMixture density and viscosity κ : mobility parameterε : mean-field thicknessΦ: chemical potential5Phase field method is implemented in OpenFOAM (foam-extend-1.6 and 3.2)As a novel top-level OpenFOAM solver phaseFieldFoam [1]C15.06.15Numerical implementation and verificationVerification by a series of test cases against analytical solutions [2][1] H. Marschall, X. Cai, M. Wörner. 2016, in preparation[2] X. Cai, H. Marschall, M. Wörner and O. Deutschmann, Chem. Eng. Technol. 2015,  38: 1985–19926C15.06.15Numerical implementation and verification[1] H. Marschall, X. Cai, M. Wörner. 2016, in preparation[2] X. Cai, H. Marschall, M. Wörner and O. Deutschmann, Chem. Eng. Technol. 2015,  38: 1985–1992Capillary rise of liquid in narrow channelPhase field method is implemented in OpenFOAM (foam-extend-1.6 and 3.2)As a novel top-level OpenFOAM solver phaseFieldFoam [1]Verification by a series of test cases against analytical solutions [2]7C15.06.15Numerical implementation and verificationCapillary-driven wetting/dewetting of droplets[1] H. Marschall, X. Cai, M. Wörner. 2016, in preparation[2] X. Cai, H. Marschall, M. Wörner and O. Deutschmann, Chem. Eng. Technol. 2015,  38: 1985–1992Phase field method is implemented in OpenFOAM (foam-extend-1.6 and 3.2)As a novel top-level OpenFOAM solver phaseFieldFoam [1]Verification by a series of test cases against analytical solutions [2]8C15.06.15Numerical implementation and verificationGravitational effect on wetting droplet[1] H. Marschall, X. Cai, M. Wörner. 2016, in preparation[2] X. Cai, H. Marschall, M. Wörner and O. Deutschmann, Chem. Eng. Technol. 2015,  38: 1985–1992Phase field method is implemented in OpenFOAM (foam-extend-1.6 and 3.2)As a novel top-level OpenFOAM solver phaseFieldFoam [1]Verification by a series of test cases against analytical solutions [2]9CViscous droplet spreadingExperiment by Zosel 1993Diameter ≈ 3 mmPIB solution µ = 25 pa∙son smooth flat PTFE surface (θe = 58º)timeDroplet spreading on flat surface3D adaptive mesh refinementReference: X. Cai, H. Marschall, M. Wörner and O. Deutschmann, Chem. Eng. Technol. 2015,  38: 1985–1992Single droplet wetting dynamics Droplet base radius over time10CExperiment by Jansen et al. 2013Glycerin droplet volume = 3 mLAlternating stripes made ofSiO2, e = 40PFDTS, e = 106Stick-slip motionDroplet spreading on chemically-heterogeneous surfaceReference: X. Cai, H. Marschall, M. Wörner and O. Deutschmann, Chem. Eng. Technol. 2015,  38: 1985–1992Single droplet wetting dynamics 11CExperiment by Jansen et al. 2013Glycerin droplet volume = 3 mLAlternating stripes made ofSiO2, e = 40PFDTS, e = 106Stick-slip motionReference: X. Cai, H. Marschall, M. Wörner and O. Deutschmann, Chem. Eng. Technol. 2015,  38: 1985–1992Single droplet wetting dynamics Droplet spreading on chemically-heterogeneous surface12e = 45°July 01, 2015Interface-resolving for Two-phase Flow in Sponge Motivation of DNS Characterization of local interfacial phenomenaProviding closure for Euler-Euler simulation 13e = 45°July 01, 2015Interface-resolving for Two-phase Flow in Sponge Source: Wallenstein et al. 2015solidliquidRepresentative Elementary Vol.(µ)CT & Reconstruction S. Meinicke, KIT-TVT STL geometry for CFD   Total Foam structureHeight: 25 – 100 mmΦ: 100 mmIndividual liquid jetsApprox. 1 – 10 mmLocal gas-liquid interfaceApprox. 0.1 – 1 mmDisparity of length scale up to 102 or 103! Motivation of DNS Characterization of local interfacial phenomenaProviding closure for Euler-Euler simulation 14Validation for Hydrodynamics of Gas FlowApply the solver for gas flow through sponge structureCompare simulated pressure drop versus superficial velocity against:experimental results (Dietrich et al. 2009*)CFD results using “simpleFoam” (Meinicke et al. 2014**)sample sponge type: Al2O3, 80% porosity, 20 ppiJuly 01, 2015• U0: superficial gas velocity• ∆p /∆z : pressure drop per unit length [1] B. Dietrich, W. Schabel, M. Kind, H. Martin. Pressure Drop Measurements of Ceramic Sponges - Determining the Hydraulic Diameter. Chem. Eng. Sci. 64 (16), 3633-3640. 2009[2]  S. Meinicke, Th. Wetzel, B. Dietrich. CFD modelling of single-phase hydrodynamics and heat transfer in solid sponges, 11th Int. Conf. on CFD in the Minerals & Proc. Industries, Conference Proceedings, Melbourne, 201515 July 01, 2015REV → difficult to get inlet liquid distribution from exp.Mirroring geometry + periodic boundary conditionsInterface-resolving for Two-phase Flow in Sponge SiSiC foam, 20 ppi, 85% porosity16 July 01, 2015Interface-resolving for Two-phase Flow in Sponge SiSiC foam, 20 ppi, 85% porosityConventionally:inlet flow rate → pressure dropIn current periodic domain:pressure drop → inlet/domain flow rate fxp P0x f xxLxxp pp P PLInput to DNS: liquid saturation ß Pressure drop ∆p/∆xOutput from DNSgas-liquid interfacial areaProviding closure for Euler-Euler(future steps) 17 July 01, 2015θe = 40°θe = 80°Effect of equilibrium contact angle wettability Interface-resolving for Two-phase Flow in Sponge Air-water on SiSiC θe = 20° - 80°18 July 01, 2015Effect of Solid Surface wettability Interface-resolving for Two-phase Flow in Sponge Gas-liquid interfacial area Ai vs. contact angle θefor different liquid saturation ßEffect of interfacial tension Gas-liquid interfacial area Ai vs. contact angle θefor different liquid saturation ß19Validation for bubble terminal rise velocityJuly 01, 2015• Air bubble rising glycerin liquid• Morton number = 0.064 Re =  ρUD / µEo = ∆ρgD2 / σ• U : terminal velocity • D :  bubble diameter 20Validation on cylinder-induced bubble breakupJuly 01, 2015• Experiment from Segers PhD thesis 2015 (Group of Prof. Kuipers and Prof. Deen, TU Eindhoven)• Cross-sectional diameter of cylinder = 3.1 mm• Equivalent diameter of bubble = 9.1 mmReference: X. Cai, M. Wörner, H. Marschall and O. Deutschmann, Catalysis Today, 2015, submitted21 July 01, 2015Experiment Segersstainless steel cylinderPhase-field Simulationθe = 60°Validation on cylinder-induced bubble breakupReference: X. Cai, M. Wörner, H. Marschall and O. Deutschmann, Catalysis Today, 2015, submitted22 July 01, 2015Validation on cylinder-induced bubble breakupEffect of surface wettability θe = 30° θe = 90°Time evolution of bubble surface area AiReference: X. Cai, M. Wörner, H. Marschall and O. Deutschmann, Catalysis Today, 2015, submitted23Periodic Open Cell Structure (POCS) July 01, 2015SEBM-manufactured by FAU Erlangen(*)(Prof. W. Schwieger, Prof. H. Freund)STL geometry for CFD provided by C.O. Möller, TUHH (Prof. M. Schlüter )Geometry parametersWindow size s = 4 mmStrut diameter ds = 1 mmGrid angle = 90°(*) M. Klumpp, A. Inayat, J. Schwerdtfeger, C. Körner, R.F. Singer, H. Freund, W. Schwieger, Chem Eng J, 242 (2014) 364-378.24Bubble Rising in Periodic Open Cell Structure July 01, 2015θe = 0° θe = 90° θe = 120°Reference: X. Cai, M. Wörner, H. Marschall and O. Deutschmann, Catalysis Today, 2015, submitteddecreasing wettability (increasing contact angle) Air bubble (D = 4 mm) rising in quiescent water within a titled POCS25Bubble Rising in Periodic Open Cell Structure July 01, 2015θe = 0° θe = 90° θe = 120°Reference: X. Cai, M. Wörner, H. Marschall and O. Deutschmann, Catalysis Today, 2015, submitteddecreasing wettability (increasing contact angle) Air bubble (D = 4 mm) rising in quiescent water within a titled POCS26Bubble Rising in Periodic Open Cell Structure July 01, 2015θe = 0° θe = 90°Reference: X. Cai, M. Wörner, H. Marschall and O. Deutschmann, Catalysis Today, 2015, submitted2D lateral view27Bubble Rising in Periodic Open Cell Structure July 01, 2015θe = 0° θe = 90°Reference: X. Cai, M. Wörner, H. Marschall and O. Deutschmann, Catalysis Today, 2015, submitted2D lateral view28Summary and OutlookPhase Field Method and phaseFieldFoam in OpenFOAMOutlook: release the code to foam-extendA series of test cases for elementary and complex wetting phenomenaOutllook: include models for contact angle hysteresis and surface roughnessInterface-resolving for two-phase flows in sponge structureOutlook: further DNS for deriving closure relation for Euler-Euler model July 01, 2015Rising bubble in periodic open-cell structure Outlook: combination of present numerical studies with experiment 29• Water droplet: Diameter = 2 mm; initial impact velocity = 0.62 m/s• PDMS surface: static contact angle = 100° (Hydrophobic)Ongoing worksDroplet impact onto solid surfaceCooperation with Institute of Fluid Mechanics (Prof. Frohnapfel), KIT t [s]r[-]Simulation     experimentDroplet base radius over timeSimulationExperiment30• Water droplet: Diameter = 2 mm; initial impact velocity = 0.62 m/s• PDMS surface: static contact angle = 140° (superhydrophobic)Ongoing worksDroplet impact onto solid surfaceCooperation with Institute of Fluid Mechanics (Prof. Frohnapfel), KIT 31CSingle droplet wetting dynamics Droplet spreading on topologically-heterogeneous surface (ongoing)Droplet spreading on structured surfaceReference: R. Bernard. Master-thesis, 201632AcknowledgementPhD study funded by Germany Helmholtz Energy Alliance “Energy-efficient chemical multiphase processes”July 01, 2015Partners:Prof. B. Frohnapfel, V. Fink (KIT-ISTM, Karlsruhe)Dr. B. Dietrich, S. Meinicke (KIT-TVT, Karlsruhe)Prof. P. Yue (Virginia Tech, USA)Prof. H. Alla(USTO, Oran, Algeria)

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Direct Numerical Simulations of Gas-liquid Flows in Subdomains of Structured Innovative Multiphase Chemical reactors

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