TY - CHAP A1 - Starick, Tommy A1 - Medina Méndez, Juan Ali A1 - Schmidt, Heiko T1 - One-Dimensional Turbulence simulations for reactive flows in open and closed systems T2 - Conference on Modelling Fluid Flow (CMFF’18), The 17th International Conference on Fluid Flow Technologies Budapest, Hungary, September 4-7, 2018 N2 - The One-Dimensional Turbulence (ODT) model is applied to reactive flows in open and closed systems represented by a lifted jet flame in a vitiated coflow, and a constant volume autoignition configuration, respectively. ODT is a one-dimensional model for turbulent flow simulations, which uses a stochastic formulation to represent the effcts of turbulent advection. Diffusion and reaction effcts along the ODT domain are considered by deterministic evolution equations. This work is an effort to verify the applicability and effiency of the model for open and closed systems. In the open system case, ODT results are compared against experimental results of a lifted methane/air jet flame detailed in the work of Cabra et al. [1]. In the closed system case, a periodic, constant volume domain is used to investigate the sensitivity of the ignition evolution to initial temperature and composition inhomogeneities of a lean n-heptane/air mixture. In the latter context, ODT results are compared to DNS results from Luong et al. [2]. Results for the jet and constant volume configuration show a reasonable match with the experimental and DNS data, considering the reduced order of the model and the underlying assumptions for each case. At the jet configuration, a dependence of the flame evolution on the turbulence intensity parameter can be seen. For the closed system, initial temperature and composition inhomogeneities allow a mitigation of the undesirable rapid pressure rise. Y1 - 2018 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Starick_2018_cmff_final_after_review.pdf ER - TY - GEN A1 - Starick, Tommy A1 - Medina Méndez, Juan Ali A1 - Schmidt, Heiko T1 - One-Dimensional Turbulence simulations for reactive flows in open and closed systems T2 - Technische Mechanik Y1 - 2019 U6 - https://doi.org/10.24352/UB.OVGU-2019-015 VL - 39 IS - 1 SP - 162 EP - 174 ER - TY - CHAP A1 - Medina Méndez, Juan Ali A1 - Glawe, Christoph A1 - Starick, Tommy A1 - Schöps, Mark Simon A1 - Schmidt, Heiko T1 - IMEX-ODTLES: A multi-scale and stochastic approach for highly turbulent flows T2 - 90th Annual Meeting of the International Association of Applied Mathematics and Mechanics February 18-22, 2019 Vienna, Austria, Abstract book Y1 - 2019 UR - https://jahrestagung.gamm-ev.de/images/2019/Photos/GAMM2019_BookofAbstracts.pdf SN - 978-3-903024-84-7 PB - TU-Verlag CY - Wien ER - TY - CHAP A1 - Starick, Tommy A1 - Schmidt, Heiko T1 - Hierarchical parcel swapping: an efficient mixing model for turbulent reactive flows T2 - 90th Annual Meeting of the International Association of Applied Mathematics and Mechanics February 18-22, 2019 Vienna, Austria, Abstract book Y1 - 2019 UR - https://jahrestagung.gamm-ev.de/images/2019/Photos/GAMM2019_BookofAbstracts.pdf SN - 978-3-903024-84-7 PB - TU-Verlag CY - Wien ER - TY - GEN A1 - Starick, Tommy A1 - Schmidt, Heiko T1 - Hierarchical Parcel Swapping: An efficient mixing model for turbulent reactive flows T2 - Proceedings in Applied Mathematics and Mechanics N2 - Hierarchical Parcel‐Swapping (HiPS) developed by A.R. Kerstein [J. Stat. Phys. 153, 142‐161 (2013)] is a computationally efficient and novel model for the effects of turbulence on time‐evolving, diffusive scalar fields. The characteristic feature of HiPS is the interpretation of the one‐dimensional flow domain or a state space as a binary tree structure. Every tree level corresponds to a specific length and time scale, which is based on a turbulence inertial range scaling. The state variables reside at the base of the tree and are interpreted as fluid parcels. The effects of turbulent advection are represented by stochastic swaps of sub‐trees at rates determined by turbulent time scales associated with the sub‐trees. The mixing of adjacent fluid parcels is done at rates consistent with the prevailing diffusion time scales. In this work, we investigate the influence of turbulent time scale variations on an isothermal series‐parallel reaction scheme. The production of a desired chemical species is evaluated by means of a defined selectivity and is strongly affected by the underlying mixing time scales. Y1 - 2019 U6 - https://doi.org/10.1002/pamm.201900492 SN - 1617-7061 VL - 19 SP - 1 EP - 2 ER - TY - GEN A1 - Starick, Tommy A1 - Medina Méndez, Juan Ali A1 - Schmidt, Heiko T1 - Towards a dynamic model adaptive combustion closure using LEM, ODT, and HiPS T2 - 17th International Conference on Numerical Combustion, May 6-8, 2019, Aachen, Germany, Book of Abstracts N2 - The computational cost of Direct Numerical Simulations (DNS) that resolve all scales rises with the cube of the Reynolds numberand is currently not feasible for real world applications. Large Eddy Simulations (LES) overcome this limitation by only resolving the large scale effects and completely model the small scaleeffects. This results in a strong dependence of the accuracy onthe chosen subgrid-scale model. The model adaptivity concept discussed in [Schmidt et al., ICDERS, 2007] dynamically uses different Linear Eddy Model (LEM) types [Kerstein, LEM, 1988] for stochastic closure to model the turbulent flame speed of apremixed flame within LES. In the talk, we will first summarize the progress of our group on One Dimensional Turbulence (ODT) [Kerstein, ODT, 1999] and Hierarchical Parcel Swapping (HiPS) [Kerstein, HiPS, 2013] based on reactive stand-alone simulations, [Jozefik et al., Combust. Flame, 2015] [Jozefik et al., Combust. Flame, 2016] [Medina et al., Combust. Flame, 2018]. Second,we will sketch a possible combination of the model adaptivity concept [Schmidt et al., ICDERS, 2007] and recent efficient ODTLES implementations [Glawe et al., Z. Angew. Math. Mech.,2018] to dynamically use LEM, ODT and HIPS together inside ofLES solvers to simulate turbulent reactive flows. Y1 - 2019 UR - https://nc19.itv.rwth-aachen.de/bookOfAbstracts.pdf SP - 143 EP - 144 CY - Aachen ER - TY - GEN A1 - Starick, Tommy A1 - Lignell, David O. A1 - Schmidt, Heiko T1 - One-Dimensional Turbulence Modelling of a Lifted Methane/Air Jet Flame in a Vitiated Coflow T2 - Proc. of the 11th International Symposium on Turbulence and Shear Flow Phenomena (TSFP11)Southampton, UK, July 30 to August 2, 2019 N2 - The present preliminary numerical study investigates alifted methane/air jet flame in a vitiated coflow by meansof the map-based, stochastic One-Dimensional Turbulence(ODT) model. In the considered configuration, a jet flameissues from a central nozzle into a vitiated coflow of hotcombustion products from an array of lean H2/air flames.Centreline profiles for mixture fraction, temperature andmass fraction of O2and OH obtained from ODT simula-tions with a planar and cylindrical formulation are shownand compared to measurements from Cabraet al.(2005).Additionally, two-dimensional renderings of the jet flameand scatter plots of temperature versus mixture fraction andOH mass fraction versus mixture fraction are provided. Al-though the application of ODT for reactive flows in jet con-figurations is not novel, the chosen lifted jet flame in a vi-tiated coflow represents a challenge for the model. The ac-curate representation of the subtle interactions of the hotcoflow products with the cold unburnt jet flow are crucialfor the reaction and autoignition of the jet (Cabraet al.,2005). Considering the reduced order of the model and thetaken assumptions, the achieved results reasonably matchwith the measurement data. Y1 - 2019 UR - http://www.tsfp-conference.org/proceedings/2019/278.pdf ER - TY - GEN A1 - Starick, Tommy A1 - Lignell, David O. A1 - Schmidt, Heiko T1 - Towards a Simple Mixing Model for Passive Scalar Transport Using Hierarchical Parcel Swapping (HIPS) T2 - 17th European Turbulence Conference (ETC2019), 3-6 September 2019, Torino, IT KW - Hierarchical Parcel Swapping (HiPS) , passice scalar transport, mixing model Y1 - 2019 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Starick_2019_ETC_Abstract_Starick.pdf UR - http://www.etc17.it/ ER - TY - GEN A1 - Starick, Tommy A1 - Medina Méndez, Juan Ali A1 - Klein, Marten A1 - Jozefik, Zoltan A1 - Schmidt, Heiko T1 - Zur jüngsten Entwicklung in der Modellierung von turbulenten Verbrennungsprozessen mittels ODT T2 - 29. Deutscher Flammentag, 17-18 September 2019, Bochum, DE N2 - Die vorliegende Arbeit befasst sich mit den jüngsten Entwicklungen und Anwendungen des One-Dimensional Turbulence (ODT) Modells auf reaktive Strömungen. Bei ODT handelt es sich um ein stochastisches und abbildungsbasiertes Turbulenzmodell zur Simulation von turbulenten Strömungen. In ODT wird das eindimensionale Rechengebiet als gedachte Linie durch das dreidimensionale Strömungsfeld verstanden, welches in Richtung des mittleren Gradienten einer Geschwindigkeit oder anderer skalarer Felder orientiert ist. Die Besonderheit von ODT liegt in der Modellierung der turbulenten Advektion durch stochastisch auftretende Wirbelereignisse. Die molekulare Diffusion und Reaktionskinetik entlang des ODT-Rechengebietes wird mittels sich zeitlich entwickelnder, deterministischer Erhaltungsgleichungen berücksichtigt und vollständig aufgelöst. In dieser Arbeit werden vorläufige ODT-Simulationsergebnisse von reaktiven Strömungen für jeweilsein offenes und ein geschlossenes System vorgestellt. Essentielle Vorarbeiten, die die Vermischungeines passiven Skalars in einer planaren Strahldüse untersuchen, werden ebenfalls gezeigt. Beim offenen System handelt es sich um eine Methan/Luft Freistrahl-Flamme in einer umgebenden Strömung aus heißen Verbrennungsgasen. Die Simulationsergebnisse werden zu Vergleichszweckenden Messungen von Cabra et al. gegenübergestellt. Beim geschlossenen System wird die Selbstzündung von mageren n-Heptan Gemischen bei niedrigen Temperaturen und komplexer Reaktionskinetik betrachtet. Hierbei werden die ODT-Ergebnisse mit den Resultaten aus einer Direkten Numerischen Simulation (DNS) verglichen. In den durchgeführten Studien konnte gezeigt werden, dass die mittels ODT erzeugten Statistiken eine beachtlich gute Übereinstimmung mit den Vergleichsdaten aufweisen. Im Hinblick auf die reduzierte Dimensionalität von ODT, die Qualitätder erzielten Ergebnisse und die erforderliche Rechenleistung, stellt ODT ein attraktives Modell zurSimulation von turbulenten und reaktiven Strömungen dar. KW - One-Dimensional Turbulence (ODT) , reaktive Strömungen Y1 - 2019 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Starick_Abstract_Flammentag_19.pdf UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Starick_2019_Flammentag19_Starick_Paper.pdf UR - http://www.leat.rub.de/index.php?do=Flammentag.html ER - TY - GEN A1 - Starick, Tommy A1 - Medina Méndez, Juan Ali A1 - Klein, Marten A1 - Jozefik, Zoltan A1 - Schmidt, Heiko T1 - Zur jüngsten Entwicklung in der Modellierung von turbulenten Verbrennungsprozessen mittels ODT Y1 - 2019 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Starick_2019_Flammentag19_Starick_Poster.pdf ER - TY - GEN A1 - Medina Méndez, Juan Ali A1 - Glawe, Christoph A1 - Starick, Tommy A1 - Schöps, Mark Simon A1 - Schmidt, Heiko T1 - IMEX-ODTLES: A multi-scale and stochastic approach for highly turbulent flows T2 - Proceedings in Applied Mathematics and Mechanics N2 - The stochastic One-Dimensional Turbulence (ODT) model is used in combination with a Large Eddy Simulation (LES) approach in order to illustrate the potential of the fully coupled model (ODTLES) for highly turbulent flows. In this work, we use a new C++ implementation of the ODTLES code in order to analyze the computational performance in a classical incompressible turbulent channel flow problem. The parallelization potential of the model, as well as its physical and numerical consistency are evaluated and compared to Direct Numerical Simulations (DNSs). The numerical results show that the model is capable of reproducing a representative part of the DNS data at a cheaper computational cost. This advantage can be enhanced in the future by the implementation of a straightforward parallelization approach. Y1 - 2019 U6 - https://doi.org/10.1002/pamm.201900433 SN - 1617-7061 VL - 19 IS - 1 ER - TY - GEN A1 - Starick, Tommy A1 - Schmidt, Heiko T1 - Stochastic modeling of a lifted methane/air jet flame T2 - 14th World Congress on Computational Mechanics (WCCM XIV) ; 8th European Congress on Computational Methods in Applied Science and Engineering (ECCOMAS 2020), July 19–24, 2020, Paris, France Y1 - 2020 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Starick_2020_WCCM_Abstract.pdf ER - TY - GEN A1 - Starick, Tommy A1 - Schmidt, Heiko T1 - Stochastische Modellierung einer Methan/Luft Freistrahl-Flamme mit detaillierter Chemie T2 - 30. Deutscher Flammentag, 28-29 September 2021, Hannover, DE Y1 - 2020 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Starick_2020_Flammentag_Abstract.pdf ER - TY - GEN A1 - Starick, Tommy A1 - Lignell, David O. A1 - Schmidt, Heiko T1 - Stochastic Modeling of a Lifted Methane/Air Jet Flame with Detailed Chemistry T2 - 91th Annual Meeting of the International Association of Applied Mathematics and Mechanics March 15-19, 2020 Kassel, DE Y1 - 2020 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Starick_2020_GAMM_Abstract.pdf ER - TY - GEN A1 - Starick, Tommy A1 - Schmidt, Heiko T1 - Stochastische Modellierung einer Methan/Luft Freistrahl-Flamme mit detaillierter Chemie T2 - 30. Deutscher Flammentag, Hannover-Garbsen, 28-29 September 2021 N2 - Die vorliegende Arbeit befasst sich mit der stochastischen Modellierung einer Methan/Luft Freistrahl-Flamme unter Verwendung des One-Dimensional Turbulence (ODT) Modells. Bei der untersuchten Cabra-Brennerkonfiguration handelt es sich um ein offenes System, bei welchem ein vorgemischter Methan/Luft Freistrahl von einer zentral angeordneten Düse in eine Umgebungsströmung aus heißen Verbrennungsgasen strömt. Das One-Dimensional Turbulence Modell ist ein stochastisches und abbildungsbasiertes Modell, welches die molekulare Diffusion und Reaktionskinetik durch sich zeitlich entwickelnde, deterministische Erhaltungsgleichungen berücksichtigt und entlang eines eindimensionalen Rechengebietes vollständig auflöst. Die Besonderheit von ODT liegt in der Modellierung der turbulenten Advektion über zufällig auftretende Wirbelereignisse, welche den fundamentalen Erhaltungseigenschaften unterliegen. Für die Abbildung der Methan/Luft Verbrennungschemie wird ein reduzierter Mechanismus mit 19 Spezies und 15 Reaktionen und ein detaillierter Mechanismus mit 53 Spezies und 325 Reaktionen eingesetzt. Die gezeigten vorläufigen ODT-Simulationsergebnisse der Methan/Luft Freistrahl-Flamme beinhalten Mittellinienprofile, radiale Profile, Streudiagramme und zweidimensionale Visualisierungen der Freistrahl-Flamme, welche mit einer zylindrischen Formulierung von ODT erzeugt wurden. Zu Vergleichszwecken werden die Simulationsergebnisse experimentellen Messungen gegenübergestellt. Obwohl die Simulation von reaktiven Freistrahl-Flammen keinen neuen Anwendungsfall von ODT darstellt, ist die akkurate Wiedergabe des sensiblen Zusammenspiels des zunächst unverbrannten Freistrahls mit der heißen Umgebungsströmung eine Herausforderung für das Modell. In der durchgeführten Studie konnte gezeigt werden, dass die mittels ODT erzeugten Statistiken eine beachtlich gute Übereinstimmung mit den Vergleichsdaten aufweisen. Im Hinblick auf die reduzierte Dimensionalität von ODT, die Qualität der erzielten Ergebnisse und die erforderliche Rechenleistung, stellt ODT ein attraktives Modell zur Simulation von turbulenten und reaktiven Strömungen dar. Y1 - 2021 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Starick_2021_Flammentag.pdf ER - TY - GEN A1 - Kerstein, Alan R. A1 - Lignell, David O. A1 - Schmidt, Heiko A1 - Starick, Tommy A1 - Wheeler, Isaac A1 - Behrang, Masoomeh T1 - Using Hips As a New Mixing Model to Study Differential Diffusion of Scalar Mixing in Turbulent Flows T2 - 2021 AIChE Annual Meeting N2 - Mixing two or more streams is ubiquitous in chemical processes and industries involving turbulent liquid or gaseous flows. Modeling turbulent mixing flows is complicated due to a wide range of time and length scales, and non-linear processes, especially when reaction is involved. On the other hand, in turbulent reacting flows, sub-grid scales need to be resolved accurately because they involve reactive and diffusive transport processes. Transported PDF methods use mixing models to capture the interaction in the sub-grid scales. Several models have been used with varying success. In this study, we present a novel model for simulation of turbulent mixing called Hierarchical Parcel Swapping (HiPS). The HiPS model is a stochastic mixing model that resolves a full range of time and length scales with the reduction in the complexity of modeling turbulent reacting flows. This model can be used as a sub-grid mixing model in PDF transport methods, as well as a standalone model. HiPS can be applied to transported scalars with variable Schmidt numbers to capture the effect of differential diffusion which is important for modeling scalars with low diffusivity like soot. We present an overview of the HiPS model, its formulation for variable Schmidt number flows, and then present results for evaluating the turbulence properties including the scalar energy spectra, the scalar dissipation rate, and Richardson dispersion. These model developments are an important step in applying HiPS to more complex flow configurations. Y1 - 2021 UR - https://plan.core-apps.com/aiche2021/event/002309c77cf108fff1a6a8a101a07ebd ER - TY - GEN A1 - Starick, Tommy A1 - Lignell, David O. A1 - Schmidt, Heiko T1 - Stochastic Modeling of a Lifted Methane/Air Jet Flame with Detailed Chemistry T2 - Proceedings in Applied Mathematics & Mechanics N2 - This preliminary numerical study investigates a lifted methane/air jet flame in a vitiated coflow by means of the One-Dimensional Turbulence (ODT) model. In the considered Cabra Burner configuration [Combust. Flame 143 491-506 (2005)], a jet flame issues from a central nozzle into a vitiated coflow of hot combustion products from lean premixed hydrogen/air flames. ODT is a map-based model for turbulent flow simulations which uses a stochastic formulation for the turbulent advection. The diffusion and reaction effects along the one-dimensional domain are considered by temporally advancing deterministic evolution equations. ODT simulations are performed with a representation of the methane/air chemistry by a detailed 53-species mechanism with 325 reactions. In this work, we present centerline profile of temperature and species concentrations obtained from ODT simulations using a cylindrical ODT-formulation. Additionally, a two-dimensional rendering of the temperature distribution is shown. Although the simulation of reactive jet configurations by means of ODT is not novel, the complex stabilization region depending on the flow conditions represents a challenge for the model. Considering the reduced order of the model, ODT is able to predict the flow characteristics and reasonably matches the existing experimental data. Y1 - 2020 UR - https://onlinelibrary.wiley.com/doi/full/10.1002/pamm.202000316 U6 - https://doi.org/10.1002/pamm.202000316 SN - 1617-7061 VL - 20 IS - 1 ER - TY - GEN A1 - Starick, Tommy A1 - Lignell, David O. A1 - Schmidt, Heiko T1 - Stochastic Modeling of a Lifted Methane/Air Jet Flame with Detailed Chemistry T2 - 91th Annual Meeting of the International Association of Applied Mathematics and Mechanics March 15-19, 2021 Kassel, DE Y1 - 2021 UR - https://onlinelibrary.wiley.com/doi/epdf/10.1002/pamm.202100237 U6 - https://doi.org/10.1002/pamm.202100237 ER - TY - GEN A1 - Xie, Tianxiao A1 - Starick, Tommy A1 - Mosgow, Anatol A1 - Berg, Heinz Peter A1 - Höschler, Klaus A1 - Schmidt, Heiko T1 - Thermofluiddynamic pre-design of a primary surface heat exchanger under the influence of heat radiation using 1D/3D coupled simulation method T2 - NAFEMS World Congress 2021, online, 25-29. Oktober 2021 N2 - Within the Framework of the "TurboFuelCell (TFC)" a highly integrated and compact energy conversion system based on Micro Gas Turbine Solid Oxide Fuel Cell (MGT-SOFC) hybrid process is being developed by the team at BTU-Cottbus Senftenberg. This work focuses on the extension of the pre-design process of a primary surface heat exchanger (PSHX), which is a key component for the coupling between MGT and SOFC, using an 1D/3D hybrid simulation method for the understanding of its behaviour under the influence of heat radiation. In a MGT-SOFC hybrid process the high temperature heat exchanger plays an important role in preheating the fresh air to a minimum operation temperature necessary for SOFC. Due to the special location of this PSHX in the TFC, it is constantly exposed to heat radiation from the SOFC module, which requires additional consideration of its influence for better model accuracy. A first design, which is later extended through an 1D Flow network model, based on 𝜖 − 𝑁𝑇𝑈 method is presented. A complete 3D-CFD simulation with consideration of heat radiation is initially employed for the whole flow process to examine the first design. However, this approach proves to be highly computationally expensive due to the large dimensional difference between the plenum for cathode exhaust air and the fine channels in the PSHX. To reduce the computational effort, the flow and heat transfer in the PSHX is modelled by 1D elements. The flow in the plenum is simulated by 3D-CFD, which better accounts for convection and thermal radiation. A comparison between 3D-CFD and 1D/3D hybrid model is performed. A significant reduction of simulation time and computing resources can be achieved for well calibrated hybrid model without compromising on accuracy. In the talk, the effect of insulation layer thickness variations on the heat transfer on the plenum side due to heat radiation and their influence on the heat exchanger efficiency are discussed. Consequently, design improvements are realized based on the previous findings. Finally, the 1D/3D hybrid simulation method is evaluated and prepared for the general applications in thermal management of machines based on coupled MGT-SOFC process. Y1 - 2021 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Starick_2021_NAFEMS_World_Congress_Manuscript.pdf UR - https://agenda.nwc21.org/session.php?s=B5 ER - TY - GEN A1 - Klein, Marten A1 - Zenker, Christian A1 - Starick, Tommy A1 - Schmidt, Heiko T1 - Stochastic modeling of three-scalar mixing in a coaxial jet using one-dimensional turbulence T2 - 12th International Symposium on Turbulence and Shear Flow Phenomena (TSFP12), Osaka, Japan (Online), July 19-22, 2022 N2 - Modeling complex mixing processes is a standing challenge for a number of applications ranging from chemical to mechanical and environmental engineering. Here, the gas-phase turbulent mixing in a three-stream concentric coaxial jet is investigated as a canonical problem. Reynolds-averaged Navier–Stokes simulations (RANS) suggest that the gas-phase mixing can be accurately modeled by air doped with passive scalars, for which small-scale resolving numerical simulations are performed with the one-dimensional turbulence (ODT) model as stand-alone tool. We show that both the spatial (S-ODT) and temporal (T-ODT) model formulations yield qualitatively similar results exhibiting reasonable to good agreement with available reference experiments, Reynolds-averaged and large-eddy simulations, as well as mixing models. This is demonstrated for low-order statistics, like the scalar variance and dissipation, but also the two-scalar joint probability density functions that can not be obtained with RANS. Our results suggest that S-ODT has better capabilities than T-ODT to model the mixing processes in the jet which we attribute to the account of local advective time scales. KW - stochastic modeling KW - one-dimensional turbulence KW - concentric coaxial round jet KW - multiple passive scalars KW - turbulent mixing KW - co-flow entrainment Y1 - 2022 UR - http://www.tsfp-conference.org/proceedings/2022/208.pdf UR - http://www.tsfp-conference.org/proceedings/proceedings-of-tsfp-12-2022-osaka.html N1 - Contribution No. 6 of 7 in Session 13C: Jets II SP - 1 EP - 6 ER - TY - GEN A1 - Starick, Tommy A1 - Behrang, Masoomeh A1 - Lignell, David O. A1 - Schmidt, Heiko A1 - Kerstein, Alan R. T1 - Turbulent mixing simulation using the Hierarchical Parcel Swapping (HiPS) model T2 - Proceedings of the Conference on Modelling Fluid Flow (CMFF’22) KW - differential diffusion, hierarchical parcel swapping, HiPS, mixing model, passive scalar mixing Y1 - 2022 UR - https://www.cmff.hu/papers/CMFF22_Final_Paper_PDF_96.pdf SN - 978-963-421-881-4 SP - 1 EP - 7 PB - Department of Fluid Mechanics, University of Technology and Economics CY - Budapest, Hungary ER - TY - GEN A1 - Starick, Tommy A1 - Schmidt, Heiko T1 - Investigation of turbulent mixing using a stochastic hierarchical parcel swapping mixing model T2 - 92nd Annual Meeting of GAMM KW - differential diffusion KW - hierarchical parcel swapping KW - HIPS KW - mixing model KW - passive scalar mixing Y1 - 2022 UR - https://jahrestagung.gamm-ev.de/wp-content/uploads/2022/08/Daily_Program_Web.pdf UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Starick_2022_HiPS_GAMM_abstract.pdf CY - Aachen, Germany ER - TY - GEN A1 - Starick, Tommy A1 - Schmidt, Heiko T1 - Investigation of turbulent mixing using a stochastic hierarchical parcel swapping mixing model T2 - Proceedings in applied mathematics and mechanics : PAMM N2 - Turbulent mixing plays an important role in a variety of applications ranging from astrophysics to combustion and even pollutant dispersion. The Direct Numerical Simulation (DNS) that resolves all scales is not feasible for most engineering applications since the flow has a wide range of length and time scales, which yields extremely high resolution requirements. Large Eddy Simulations (LES) overcome this limitation by modeling the sub-grid scale effects. In transported Probability Density Function (PDF) methods, the key challenge is to develop an accurate mixing model. At this point, the Hierarchical Parcel-Swapping (HiPS) model, introduced by A.R. Kerstein [J. Stat. Phys. 153, 142-161 (2013)], is an attractive candidate. It is characterized by a computationally efficient representation of the effects of turbulence on a time-evolving structure of diffusive scalar fields. The interpretation of the diffusive scalar fields or a state space as a binary tree structure is an alternative approach compared to the most common mixing models. The characteristic feature of HiPS is that every level of the tree corresponds to a specific length and time scale, which is based on turbulence inertial range scaling. The state variables only reside at the base of the tree and are understood as fluid parcels. The effects of turbulent advection are represented by stochastic swaps of sub-trees at rates determined by prevailing turbulent time scales associated with the sub-trees. The mixing of adjacent fluid parcels is done either instantaneously or at rates consistent with the corresponding diffusion time scales. In this work, HiPS is detailed for the simulation of passive scalar mixing first. Preliminary results for the scalar power spectra, mean square displacement and scalar dissipation rate are shown and reveal a reasonable agreement with experimental findings. Furthermore, the integrated binary tree structure allows to satisfy a large number of criteria for a good mixing model. Considering the reduced order and computational efficiency, HiPS is an attractive candidate for modeling the mixing in transported PDF methods. Y1 - 2023 U6 - https://doi.org/10.1002/pamm.202200283 SN - 1617-7061 N1 - Special Issue: 92nd Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM) VL - 22 IS - 1 ER - TY - GEN A1 - Xie, Tianxiao A1 - Mathiazhagan, Akilan A1 - Barkowski, Daniel A1 - Starick, Tommy A1 - Berg, Heinz Peter A1 - Höschler, Klaus T1 - Comparison of convective heat transfer in metal foam-filled channels of three different cross-sections T2 - Numerical Heat Transfer, Part A: Applications N2 - This work introduces a new approach of analyzing convective heat transfer in porous medium by considering the foam structure as a type of fin. It provides the resulting heat transfer characteristics for the design of a longitudinally flowed tube bundle reformer used for the Micro Gas Turbine Solid Oxide Fuel Cell (MGT-SOFC) hybrid process. Owing to a limited experimental database available in literature for the above-mentioned situation, a physical model is initially introduced for a channel flow configuration between two large flat plates using a commercial PDE solver. This model is then validated with experimental results available in literature. A comparison with theoretical solutions is also conducted. Later, this model is modified/adapted for a pipe flow configuration. The physical model for a channel with representative cross-section shape of a longitudinally flowed tube bundle is more complex and is therefore built in a commercial CFD-Solver. A comparative study of the heat transfer behavior in channels of different cross-sections is performed based on a new dimensionless correlation, whose physical coherence with fin efficiency is explained and mathematically proved. The applicability of the heat transfer correlation from one cross-sectional shape to the other are discussed. The proposed new treatment of the porous medium as a fin structure considerably simplifies the heat transfer analysis in porous medium by the clear physical meaning behind fin efficiency and Biot number. This relationship contributes to a better understanding of the heat heat transfer characteristics in porous media in contrast to the correlation between Nusselt number and Reynolds number. Furthermore, this correlation enables a direct comparison between foam structures of different parameters because the fin efficiency is always between 0 and 1. The strong physical background of new correlations also enhances the reliability and plausibility at characterizing and designing the metal foam for heat transfer enhancement. KW - Channel flow with different cross-section KW - Forced convection KW - Heat transfer in porous media KW - New heat transfer correlations Y1 - 2023 U6 - https://doi.org/10.1080/10407782.2023.2181892 SN - 1521-0634 SN - 1040-7782 VL - 85 IS - 2 SP - 222 EP - 236 ER - TY - GEN A1 - Starick, Tommy A1 - Schmidt, Heiko T1 - Stochastic modeling of turbulent mixing based on a hierarchical swapping of fluid parcels T2 - Proceedings in Applied Mathematics and Mechanics N2 - Turbulent mixing is an omnipresent phenomenon that constantly affects our everyday life and plays an important role in a variety of industrial applications. The simulation of turbulent mixing poses great challenges, since the full resolution of all relevant length and time scales is associated with an immense computational effort. This limitation can be overcome by only resolving the large-scale effects and completely model the sub-grid scales. The development of an accurate sub-grid mixing model is therefore a key challenge to capture all interactions in the sub-grid scales. At this place, the hierarchical parcel-swapping (HiPS) model formulated by A.R. Kerstein [J. Stat. Phys. 153, 142–161 (2013)] represents a computationally efficient and scale-resolving turbulent mixing model. HiPS mimics the effects of turbulence on time-evolving, diffusive scalar fields. In HiPS, the diffusive scalar fields or a state space is interpreted as a binary tree structure, which is an alternative approach compared to the most common mixing models. Every level of the tree represents a specific length and time scale, which is based on turbulence inertial range scaling. The state variables are only located at the base of the tree and are treated as fluid parcels. The effects of turbulent advection are represented by stochastic swaps of sub-trees at rates determined by turbulent time scales associated with the sub-trees. The mixing only takes places between adjacent fluid parcels and at rates consistent with the prevailing diffusion time scales. In this work, the HiPS model formulation for the simulation of passive scalar mixing is detailed first. Preliminary results for the mean square displacement, passive scalar probability density function (PDF) and scalar dissipation rate are given and reveal the strengths of the HiPS model considering the reduced order and computational efficiency. These model investigations are an important step of further HiPS advancements. The integrated auxiliary binary tree structure allows HiPS to satisfy a large number of criteria for a good mixing model. From this point of view, HiPS is an attractive candidate for modeling the mixing in transported PDF methods. Y1 - 2023 U6 - https://doi.org/10.1002/pamm.202300280 SN - 1617-7061 N1 - Special Issue: 93rd Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM), December 2023 VL - 23 IS - 4 SP - 1 EP - 8 ER - TY - GEN A1 - Starick, Tommy A1 - Schmidt, Heiko T1 - Stochastic map-based modeling of a lifted methane/air jet flame in a vitiated coflow T2 - Proceedings of the Thirteenth International Symposium on Turbulence and Shear Flow Phenomena (TSFP13) (2024) Montreal Y1 - 2024 UR - http://www.tsfp-conference.org/proceedings/2023/13.pdf VL - 2024 ER - TY - GEN A1 - Lignell, David O. A1 - Behrang, Masoomeh A1 - Kerstein, Alan R. A1 - Wheeler, Isaac A1 - Starick, Tommy A1 - Schmidt, Heiko T1 - Investigation of turbulent mixing of scalars with arbitrary Schmidt numbers using the stochastic Hierarchical Parcel Swapping Model T2 - 77th Annual Meeting of the Division of Fluid Dynamics, November 24–26, 2024; Salt Lake City, Utah N2 - Hierarchical Parcel Swapping (HiPS) is a stochastic model of turbulent mixing. HiPS is based on a binary tree structure consisting of nodes emanating from the top of the tree and terminating in parcels at the base of the tree containing fluid properties. Length scales decrease geometrically with increasing tree level, and corresponding time scales follow inertial range scaling. Turbulent mixing is modeled by swapping subtrees at different tree levels. Swaps involving single parcels result in micromixing that changes scalar states. Swaps are implemented as a Poisson process at rates corresponding to level time scales. HiPS is extended to simulation of multiple scalars with arbitrary diffusivities, considering transport in the inertial, viscous-advective, and inertial-diffusive ranges. Fundamental analysis of particle dispersion is presented with comparisons to theoretical results and DNS data in the inertial and viscous ranges. Scalar energy spectra are analysed in the three ranges and reproduce known scaling exponents. Scalar dissipation statistics are analysed and reproduce the experimental and theoretical lognormal distribution with negative skewness represented by a stretched-exponential function. DNS data are used to evaluate empirical coefficients, facilitating quantitative applications. The physical fidelity demonstrated with HiPS suggests its use as a low-cost subgrid model for coarse-grained flow simulation, for which parcel-pair mixing is a common treatment. KW - turbulent mixing KW - variable Schmidt number KW - stochastic modeling KW - hierarchical parcel swapping Y1 - 2024 UR - https://meetings.aps.org/Meeting/DFD24/Session/X39.11 PB - American Physical Society ER - TY - GEN A1 - Klein, Marten A1 - Zenker, Christian A1 - Starick, Tommy A1 - Schmidt, Heiko T1 - Stochastic modeling of multi-stream mixing based on one-dimensional turbulence T2 - 77th Annual Meeting of the Division of Fluid Dynamics N2 - Measurements of multiple scalar mixing in a turbulent jet show a strong location dependence of the scalar fluctuations and mixing processes. Mixing is quantitatively described by the state space of scalar fluctuations in terms of a joint probability density function (JPDF). The JPDF evolves in the downstream and radial directions and has non-Gaussian shape which is a burden for mixing modeling since factoring into marginal distribution functions is not permissible. Stochastic simulations based on one-dimensional turbulence (ODT) are able to reasonably reproduce the JPDF and its spatial evolution by a parabolic marching problem that circumvents constraints of the underlying elliptic problem. The model reproduces the inertial-advective range (exponent -5/3) and predicts the emergence of the viscous-advective range (exponent -1) at higher wavenumbers as the Schmidt number increases. The model offers full-scale resolution at affordable cost providing means to reasonably capture state-space statistics of turbulent mixing. KW - turbulent mixing KW - one-dimensional turbulence KW - coaxial jet KW - multi-stream mixing Y1 - 2024 UR - https://meetings.aps.org/Meeting/DFD24/Session/ZC40.4 PB - American Physical Society ER - TY - GEN A1 - Klein, Marten A1 - Zenker, Christian A1 - Starick, Tommy A1 - Schmidt, Heiko T1 - Stochastic modeling of multiple scalar mixing in a three-stream concentric coaxial jet based on one-dimensional turbulence T2 - International Journal of Heat and Fluid Flow N2 - Modeling turbulent mixing is a standing challenge for nonpremixed chemically reacting flows. Key complications arise from the requirement to capture all relevant scales of the flow and the necessity to distinguish between turbulent advective transport and molecular diffusive transport processes. In addition, anisotropic mean shear, variable advection time scales, and the coexistence of turbulent and nonturbulent regions need to be represented. The fundamental issues at stake are addressed by investigating multi-scalar mixing in a three-stream coaxial jet with a map-based stochastic one-dimensional turbulence model. ODT provides full-scale resolution at affordable costs by a radical reduction of complexity compared to high-fidelity Navier–Stokes solvers. The approach is partly justified by an application of the boundary-layer approximation, but neglects fluctuating axial pressure gradients. It is demonstrated that low-order scalar statistics are reasonably but not fully captured. Despite this shortcoming, it is shown that the model is able to reproduce experimental state-space statistics of multi-stream multi-scalar mixing. The model therefore offers physics-compatible improvements in multi-stream mixing modeling despite some fundamental limitations that remain from unjustified assumptions. KW - map-based stochastic advection modeling KW - multiple passive scalars KW - one-dimensional turbulence KW - turbulent jet KW - turbulent mixing Y1 - 2023 U6 - https://doi.org/10.1016/j.ijheatfluidflow.2023.109235 SN - 0142-727X N1 - This article is part of the "TSFP12 Special Issue". VL - 104 SP - 1 EP - 17 ER - TY - GEN A1 - Klein, Marten A1 - Starick, Tommy A1 - Zenker, Christian A1 - Medina Méndez, Juan Alí A1 - Schmidt, Heiko T1 - Reduced order stochastic modeling of turbulent mixing based on conservative baker’s maps T2 - Proceedings of the 14th International ERCOFTAC Symposium on Engineering Turbulence Modelling and Measurements (ETMM-14) N2 - The detailed numerical representation of turbulent mixing processes is a standing challenge for non-premixed chemically reacting flows. The full range of relevant flow scales needs to be captured and it is also necessary to distinguish turbulent advective from molecular diffusive processes in order to represent Reynolds and Schmidt number effects. These requirements are addressed here by utilizing two different map-based stochastic turbulence modeling strategies. The one-dimensional turbulence (ODT) model utilizes event-based turbulence modeling, whereas the hierarchical parcel-swapping (HiPS) model is a fully event-based mixing model. ODT provides full-scale resolution at affordable costs by dimensional model reduction based on the boundary-layer approximation to shear flow. HiPS is far less costly than ODT but currently limited to locally homogeneous isotropic turbulence. The physics-compatible modeling capabilities with respect to phase-space representation of turbulent mixing are demonstrated for two canonical cases using standalone model formulations. KW - turbulent mixing KW - one-dimensional turbulence (ODT) KW - hierarchical parcel swapping (HiPS) KW - stochastic turbulence modeling KW - round jet KW - passive scalar Y1 - 2023 UR - https://etmm.ercoftac.org/etmm/program/conference-program/ UR - https://drive.google.com/file/d/1q2BDOO5bXfqq0Y4z4HCGndiFI033bPyg/view?usp=drive_link SP - 613 EP - 618 PB - ERCOFTAC CY - Barcelona, Spain ER - TY - GEN A1 - Starick, Tommy A1 - Behrang, Masoomeh A1 - Lignell, David O. A1 - Schmidt, Heiko A1 - Kerstein, Alan R. T1 - Turbulent mixing simulation using the Hierarchical Parcel-Swapping (HiPS) model T2 - Technische Mechanik N2 - Turbulent mixing is an omnipresent phenomenon that permanently affects our everyday life. Mixing processes also plays an important role in many industrial applications. The full resolution of all relevant flow scales often poses a major challenge to the numerical simulation and requires a modeling of the small-scale effects. In transported Probability Density Function (PDF) methods, the simplified modeling of the molecular mixing is a known weak point. At this place, the Hierarchical Parcel-Swapping (HiPS) model developed by A.R. Kerstein [J. Stat. Phys. 153, 142-161 (2013)] represents a computationally efficient and novel turbulent mixing model. HiPS simulates the effects of turbulence on time-evolving, diffusive scalar fields. The interpretation of the diffusive scalar fields or a state space as a binary tree structure is an alternative approach compared to existing mixing models. The characteristic feature of HiPS is that every level of the tree corresponds to a specific length and time scale, which is based on turbulence inertial range scaling. The state variables only reside at the base of the tree and are understood as fluid parcels. The effects of turbulent advection are represented by stochastic swaps of sub-trees at rates determined by turbulent time scales associated with the sub-trees. The mixing of adjacent fluid parcels is done at rates consistent with the prevailing diffusion time scales. In this work, a standalone HiPS model formulation for the simulation of passive scalar mixing is detailed first. The generated scalar power spectra with forced turbulence shows the known scaling law of Kolmogorov turbulence. Furthermore, results for the PDF of the passive scalar, mean square displacement and scalar dissipation rate are shown and reveal a reasonable agreement with experimental findings. The described possibility to account for variable Schmidt number effects is an important next development step for the HiPS formulation. This enables the incorporation of differential diffusion, which represents an immense advantage compared to the established mixing models. Using a binary structure allows HiPS to satisfy a large number of criteria for a good mixing model. Considering the reduced order and associated computational efficiency, HiPS is an attractive mixing model, which can contribute to an improved representation of the molecular mixing in transported PDF methods. KW - differential diffusion KW - hierarchical parcel-swapping KW - HiPS KW - mixing model KW - scalar mixing Y1 - 2023 U6 - https://doi.org/10.24352/UB.OVGU-2023-044 SN - 0232-3869 VL - 43 IS - 1 SP - 49 EP - 58 ER - TY - GEN A1 - Behrang, Masoomeh A1 - Starick, Tommy A1 - Wheeler, Isaac A1 - Schmidt, Heiko A1 - Kerstein, Alan A1 - Lignell, David T1 - Hierarchical parcel-swapping representation of turbulent mixing : part 4 : extension to the viscous range and to mixing of scalars with non-unity Schmidt numbers T2 - Journal of fluid mechanics N2 - Hierarchical parcel swapping (HiPS) is a multiscale stochastic model of turbulent mixing based on a binary tree. Length scales decrease geometrically with increasing tree level, and corresponding time scales follow inertial range scaling. Turbulent eddies are represented by swapping subtrees. Lowest-level swaps change fluid parcel pairings, with new pairings instantly mixed. This formulation suitable for unity Schmidt number Sc is extended to non-unity Sc. For high Sc, the tree is extended to the Batchelor level, assigning the same time scale (governing the rate of swap occurrences) to the added levels as the time scale at the base of the Sc=3 tree. For low Sc, a swap at the Obukhov–Corrsin level mixes all parcels within corresponding subtrees. Well-defined model analogues of turbulent diffusivity, and mean scalar-variance production and dissipation rates are identified. Simulations idealising stationary homogeneous turbulence with an imposed scalar gradient reproduce various statistical properties of viscous-range and inertial-range pair dispersion, and of the scalar power spectrum in the inertial-advective, inertial-diffusive and viscous-advective regimes. The viscous-range probability density functions of pair separation and scalar dissipation agree with applicable theory, including the stretched-exponential tail shape associated with viscous-range scalar intermittency. Previous observation of that tail shape for Sc=1, heretofore not modelled or explained, is reproduced. Comparisons to direct numerical simulation allow evaluation of empirical coefficients, facilitating quantitative applications. Parcel-pair mixing is a common mixing treatment, e.g. in subgrid closures for coarse-grained flow simulation, so HiPS can improve model physics simply by smarter (yet nearly cost-free) selection of pairs to be mixed. KW - Turbulence modelling KW - Coupled diffusion and flow KW - Dispersion Y1 - 2025 U6 - https://doi.org/doi:10.1017/jfm.2025.10512 SN - 0022-1120 VL - 1020 SP - 1 EP - 39 PB - Cambridge University Press CY - Cambridge ER - TY - GEN A1 - Starick, Tommy A1 - Schmidt, Heiko T1 - Numerical investigation of a lifted methane/air jet flame using stochastic map-based turbulence modeling T2 - Proceedings of the Conference on Modelling Fluid Flow CMFF’25 N2 - This numerical study investigates a lifted methane/air jet flame in a vitiated coflow by means of the map-based, stochastic one-dimensional turbulence (ODT) model. The dimensional reduction of ODT allows for simulations with affordable computational costs and provides nonetheless full-scale resolution along a notional line of sight crossing the turbulent flow field. The considered Cabra burner configuration consists of a jet flame issuing from a central nozzle into a vitiated coflow of hot combustion products. Radial and centerline profiles for mixture fraction, temperature and selected species mass fractions obtained from ODT using a reduced and detailed reaction mechanism are in appropriate agreement with the existing experimental measurements. A two-dimensional illustration of the autoignition index is given, which enables the distinction between autoignition and propagation driven reaction zones. Additionally, the sensitivity of the jet combustion to velocity and temperature variations is investigated. Considering the reduced order of ODT and the sensitivity of the subtle interactions of the hot coflow with the cold jet on the entire reaction process, ODT is able to predict the flow characteristics and reasonably matches the experimental data. As a consequence, ODT is an efficient and alternative model for turbulent reactive flow simulations. KW - Autoigniton KW - Lifted jet flame KW - Methane/air combustion KW - ODT KW - One-dimensional turbulence KW - Stochastic turbulence modeling Y1 - 2025 UR - https://www.cmff.hu/papers25/CMFF25_Final_Paper_PDF_63.pdf SN - 978-615-112-002-6 SP - 1 EP - 8 PB - Department of Fluid Mechanics, Faculty of Mechanical Engineering, Budapest University of Technology and Economics CY - Budapest ER - TY - GEN A1 - Behrang, Masoomeh A1 - Starick, Tommy A1 - Schmidt, Heiko A1 - Lignell, David O. T1 - A C++ library for turbulent mixing simulation using Hierarchical Parcel Swapping (HiPS) T2 - SoftwareX N2 - Turbulence models are crucial for simulating flows at all scales, capturing both large-scale structures and small-scale mixing. Software libraries that implement such models should support modular integration, customization, and scalability across different simulation frameworks. This paper presents Hierarchical Parcel Swapping (HiPS), a C++ library documented with Doxygen and available on GitHub. HiPS supports both mixing and reactions and can be used as a standalone model or as a subgrid model in CFD simulations. The code includes examples for users to run it as a standalone model. Additionally, considerations for using it as a subgrid model are provided. KW - Mixing KW - Reaction KW - Simulation KW - Turbulence Y1 - 2025 U6 - https://doi.org/10.1016/j.softx.2025.102331 SN - 2352-7110 VL - 31 SP - 1 EP - 7 PB - Elsevier BV CY - Amsterdam ER -