TY - GEN A1 - Klein, Marten A1 - Zenker, Christian A1 - Schmidt, Heiko T1 - Small-scale resolving simulations of the turbulent mixing in confined planar jets using one-dimensional turbulence T2 - Chemical Engineering Science Y1 - 2019 SN - 0009-2509 VL - 204 SP - 186 EP - 202 ER - TY - GEN A1 - Ghasemi, Abouzar A1 - Klein, Marten A1 - Will, Andreas A1 - Harlander, Uwe T1 - Mean flow generation by an intermittently unstable boundary layer over a sloping wall T2 - Journal of Fluid Mechanics Y1 - 2018 U6 - https://doi.org/10.1017/jfm.2018.552 SN - 1750-6859 IS - vol. 853 SP - 111 EP - 149 ER - TY - GEN A1 - Klein, Marten A1 - Schmidt, Heiko T1 - Investigating the skin friction drag across electrolytes and electrical fields using one-dimensional turbulence modeling T2 - European Drag Reduction and Flow Control Meeting, EDRFCM 2019, March 26-29 2019, Bad Herrenalb, Germany KW - electrohydrodynamic flows KW - Couette flow KW - turbulence modeling Y1 - 2019 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Klein_2019_Klein+Schmidt_ODT_EHD_Couette_EDRFCM19.pdf UR - http://www.edrfcm.science/index.php/program SP - 1 EP - 2 ER - TY - GEN A1 - Klein, Marten A1 - Lignell, David O. A1 - Schmidt, Heiko T1 - Stochastic modeling of temperature and velocity statistics in spherical-shell convection T2 - Geophysical Research Abstracts, Vol. 21, EGU2019-2220 KW - turbulent convection KW - turbulence modeling KW - spherical shell Y1 - 2019 UR - https://meetingorganizer.copernicus.org/EGU2019/EGU2019-2220.pdf ER - TY - GEN A1 - Schmidt, Heiko A1 - Klein, Marten T1 - Simulating neutrally and stably stratified turbulent Ekman flows with a stochastic turbulence model T2 - Proc. of the 17th European Turbulence Conference (ETC17), 3-6 September 2019, Torino, Italy KW - turbulent boundary layer KW - turbulence modeling KW - Coriolis effects KW - stratification effects Y1 - 2019 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Klein_2019_etc.pdf UR - http://www.etc17.it/ ER - TY - GEN A1 - Sommeria, Joel A1 - Vincze, Miklos A1 - Fenyvesi, Nora A1 - Klein, Marten A1 - Viboud, Samuel A1 - Ashkenazy, Yosef T1 - Ekman layer resonance in an ocean-analog rotating tank experiment T2 - 17th European Turbulence Conference, Turin, 3 Sep 2019 - 6 Sep 2020 KW - Rotating and swirling flows KW - Circulation and currents KW - Coriolis effects Y1 - 2019 UR - http://www.etc17.it/ ER - TY - GEN A1 - Klein, Marten A1 - Schmidt, Heiko T1 - Investigating Rayleigh-Bénard convection at low Prandtl numbers using one-dimensional turbulence modeling T2 - Proc. of the 11th International Symposium on Turbulence and Shear Flow Phenomena (TSFP11), Southampton, UK, July 30 to August 2, 2019 KW - turbulent convection KW - turbulence modeling KW - low Prandtl number KW - high Rayleigh number Y1 - 2019 UR - http://www.tsfp-conference.org/proceedings/2019/14.pdf ER - TY - GEN A1 - Klein, Marten A1 - Schmidt, Heiko T1 - Investigating thermal convection at low Prandtl numbers using one-dimensional turbulence KW - turbulent convection KW - turbulence modeling KW - low Prandtl number KW - high Rayleigh number Y1 - 2019 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Klein_2019_poster_tsfp11_evince-print.pdf N1 - Poster shown at 11th International Symposium on Turbulence and Shear Flow Phenomena (TSFP11), 30 July - 2 August 2019, Southampton, UK ER - TY - GEN A1 - Klein, Marten A1 - Schmidt, Heiko T1 - The transition to the ultimate regime of thermal convection from a stochastic one-dimensional turbulence perspective T2 - arXiv KW - Rayleigh-Bénard convection KW - turbulence modeling KW - low Prandtl number KW - turbulent transitions KW - heat transfer Y1 - 2019 UR - https://arxiv.org/abs/1906.06621 SP - 1 EP - 11 ER - TY - GEN A1 - Rakhi, Rakhi A1 - Klein, Marten A1 - Medina Méndez, Juan Ali A1 - Schmidt, Heiko T1 - One-dimensional turbulence modelling of incompressible temporally developing turbulent boundary layers with comparison to DNS T2 - Journal of Turbulence N2 - The incompressible temporally developing turbulent boundary layer (TBL) is analysed using the map-based stochastic one-dimensional turbulence (ODT) model. The TBL is a canonical flow problem, which is, in the present study, formed by a planar moving wall and a free stream at rest. An understanding of this idealised flow is of fundamental relevance for the numerical analysis of turbulent boundary-layer-type flows. In the present ODT simulations, the flow variables are resolved on all scales along a wall-normal, one-dimensional domain. These variables are evolved by a deterministic and a stochastic process. The latter models the effect of turbulent advection and pressure fluctuations, whereas the former represents molecular diffusion. The model is appropriate for high Reynolds numbers for which the turbulence field exhibits a broad range of scales and is notionally featureless. We show that ODT is able to capture salient features of the TBL by comparing the various statistics with available reference direct numerical simulation (DNS) results for different bulk Reynolds numbers in the range 250 ≤ Reb ≤ 2000 using fixed model parameters. The influence of the model parameters is analysed for Reb = 1000 and optimal parameter values are provided. The results discussed in this paper suggest that ODT is an economical and reasonably accurate approach for the simulation of transient turbulent boundary-layer-type flows. KW - one-dimensional turbulence KW - stochastic modeling KW - turbulent boundary layers Y1 - 2019 U6 - https://doi.org/10.1080/14685248.2019.1674859 SN - 1468-5248 VL - 20 IS - 8 SP - 506 EP - 543 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 - Klein, Marten A1 - Schmidt, Heiko T1 - One-Dimensional Turbulence investigation of variable density effects due to heat transfer in a low Mach number internal air flow T2 - International Journal of Heat and Fluid Flow N2 - A novel spatial formulation of the One-Dimensional Turbulence (ODT) model is applied to a vertical pipe-flow with heat transfer, analogous to the Direct Numerical Simulation (DNS) performed by Bae et al. [Phys. Fluids 18, (075102) (2006)]. The framework presented here is an extension for radially confined domains of the cylindrical ODT spatial formulation for low Mach number flows with variable density. The variable density simulations for air (Prandtl number Pr = 0.71) are performed at an initial bulk Reynolds number Reb (DNS) = 6000 and Grashof number Gr (DNS) = 6.78*10^6. ODT results are presented for both the spatial formulation introduced in this work and the standard temporal formulation for cylindrical flows introduced by Lignell et al. [Theor. Comput. Fluid Dyn. 32, 4 (2018), pp. 495–520]. Streamwise bulk profiles and radial profiles at specific streamwise positions for the temporal and spatial formulations are in good agreement with the DNS results from Bae et al. For the present application, the spatial formulation yields physically better results in comparison to the temporal formulation. Overall, the findings in the original work of Bae et al. were corroborated with ODT. Although the framework proposed in this work is not a compressible framework and has some clear limitations regarding conservation properties, we suggest its use for future studies in the low Mach number variable density regime. Y1 - 2019 UR - http://www.sciencedirect.com/science/article/pii/S0142727X19301596 U6 - https://doi.org/10.1016/j.ijheatfluidflow.2019.108481 SN - 0142-727X SN - 1879-2278 VL - 80 ER - TY - GEN A1 - Kurgansky, Michael V. A1 - Seelig, Torsten A1 - Klein, Marten A1 - Will, Andreas A1 - Harlander, Uwe T1 - Mean flow generation due to longitudinal librations of sidewalls of a rotating annulus T2 - Geophysical & Astrophysical Fluid Dynamics N2 - Laboratory experiments with a rotating cylindrical annulus arereported that reveal a prograde jet, which is adjacent to a (longitu-dinally) librating inner straight cylindrical wall. Here, wall libration isrealised as a time-harmonic modulation of the inner cylinder’s rota-tion rate. The outer cylindrical wall and bottom and top lids rotatewith constant angular velocity. The main purpose of our study is tocontribute to a qualitative and quantitative understanding of non-linearities that are present in oscillating, but centrifugally stable,vertical boundary layers frequently encountered in rotating wall-bounded flows. We consider a problem that is in a sense comple-mentary to that of previous works that focused on oscillating Ekmanlayers but neglected the vertical Stokes−Stewartson layers. A sim-ple analytical model is proposed that is able to predict the magni-tude and spatial structure of the emerging prograde near-wall jet interms of nonlinearity inherent in the inner cylinder’s boundary layerdynamics. KW - boundary layer structure KW - geophysical and geological flows KW - longitudinal libration Y1 - 2020 U6 - https://doi.org/10.1080/03091929.2019.1692829 SN - 1029-0419 VL - 114 IS - 6 SP - 762 ER - TY - GEN A1 - Klein, Marten A1 - Schmidt, Heiko T1 - Stochastic modeling of passive scalars in turbulent channel flows T2 - Jahresbericht 2020 zum Band: Notes on Numerical Fluid Mechanics and Multidisciplinary Design - New Results in Numerical and Experimental Fluid Mechanics XIII KW - one-dimensional turbulence KW - passive scalar KW - channel flow Y1 - 2020 UR - https://www.dlr.de/as/Portaldata/5/Resources/dokumente/veranstaltungen/stab_workshop/STAB-Jahresbericht-2020.pdf VL - 2020 SP - 30 EP - 31 PB - Deutsche Strömungsmechanische Arbeitsgemeinschaft, STAB CY - Göttingen ER - TY - GEN A1 - Klein, Marten A1 - Schmidt, Heiko T1 - Towards a stochastic model for electrohydrodynamic turbulence with application to electrolytes T2 - Proceedings in Applied Mathematics and Mechanics N2 - We investigate turbulent Couette flows of dilute, weakly-conducting electrolytes by utilizing the stochastic one-dimensional turbulence (ODT) model. The flow is driven by relative motion of the top and bottom wall and affected by an electric field between these walls that is prescribed by a voltage difference. The electrolytes considered have zero bulk charge and consist of two ion species with the same mobility, valence, and initial concentration. The stochastic model predicts a decrease of the mean streamwise velocity when an external voltage is applied provided that both Schmidt (Sc) and Reynolds (Re) numbers are sufficiently large, that is, Sc > 30 for Re = 12000 investigated. The effect observed is relevant for flow control, but the mechanism awaits clarification. Present ODT results may help to develop this understanding or design laboratory experiments. KW - one-dimensional turbulence KW - electroconvection KW - EHD turbulence KW - Couette flow KW - electrolyte flow Y1 - 2020 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Klein_2020_EHD-Couette_PAMM.pdf U6 - https://doi.org/10.1002/pamm.202000128 VL - 2020 IS - 20 SP - 1 EP - 2 PB - Wiley-VCH CY - Weinheim ER - TY - GEN A1 - Sharma, Sparsh A1 - Klein, Marten A1 - Schmidt, Heiko A1 - Sarradj, Ennes T1 - On a lower-order framework for jet noise prediction based on one-dimensional turbulence T2 - arXiv N2 - Noise prediction requires the resolution of relevant acoustic sources on all scales of a turbulent flow. High-resolution direct numerical and large-eddy simulation would be ideal but both are usually too costly despite developments in high performance computing. Lower-order modeling approaches are therefore of general interest. A crucial but standing problem for accurate predictive modeling is the estimation of missing noise from the modeled scales. In this paper we address this problem by presenting a novel lower-order framework that couples the one-dimensional turbulence model to the Ffowcs-Williams and Hawkings approach for prediction of the far-field noise of a subsonic turbulent round jet. KW - Ffowcs-Williams and Hawkings equation KW - jet noise KW - one-dimensional turbulence KW - turbulent mixing noise Y1 - 2020 UR - https://arxiv.org/abs/2010.11050 SP - 1 EP - 4 ER - TY - GEN A1 - Klein, Marten A1 - Schmidt, Heiko T1 - Predictive modeling of passive scalar transfer to a wall using stochastic one-dimensional turbulence T2 - arXiv N2 - Passive scalars in turbulent channel flows are investigated as canonical problem for heat and mass transfer in turbulent boundary-layer flows. The one-dimensional turbulence model is used to numerically investigate the Schmidt and Reynolds number dependence of the scalar transfer to a wall due to fluctuating wall-normal transport. First, the model is calibrated for low-order velocity statistics. After that, we keep the model parameters fixed and investigate low-order passive scalar statistics for a relevant Schmidt and Reynolds number range. We show that the model consistently predicts the boundary layer structure and the scaling regimes, for which it is close to asymptotic one-dimensional theory. KW - one-dimensional turbulence KW - passive scalar KW - turbulent channel flow KW - mass transfer coefficient KW - high Schmidt number Y1 - 2020 UR - https://arxiv.org/abs/2011.04818 ER - TY - GEN A1 - Schmidt, Heiko A1 - Medina Méndez, Juan Ali A1 - Klein, Marten T1 - EHD turbulence in channel flows with inhomogeneous electrical fields: a one-dimensional turbulence study T2 - 14th World Congress on Computational Mechanics (WCCM) ; ECCOMAS Congress 2020, 19–24 July 2020, Paris, France KW - EHD turbulence; channel flow; electrolyte flow; electrostatic precipitator; one-dimensional turbulence; stochastic modeling Y1 - 2020 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Schmidt_2020_EHD-channel-flows_WCCM-abstract.pdf UR - https://slideslive.com/38946214 U6 - https://doi.org/10.23967/wccm-eccomas.2020.131 ER - TY - GEN A1 - Klein, Marten A1 - Schmidt, Heiko T1 - Modeling one and two passive scalar mixing in turbulent jets using one-dimensional turbulence T2 - 14th World Congress on Computational Mechanics (WCCM) ; ECCOMAS Congress 2020, 19–24 July 2020, Paris, France KW - one-dimensional turbulence KW - passive scalar KW - turbulent mixing KW - turbulent jet Y1 - 2020 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Klein_2020_scalars_in_jets_WCCM-abstract.pdf UR - https://www.wccm-eccomas2020.org ER - TY - GEN A1 - Klein, Marten A1 - Lignell, David O. A1 - Schmidt, Heiko T1 - MS404: Map-based stochastic methods for accurate modeling of turbulent heat and mass transfer 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 KW - heat and mass transport KW - map-based stochastic modeling KW - turbulent mixing KW - convection KW - clouds Y1 - 2020 UR - https://www.wccm-eccomas2020.org/admin/Files/FileAbstract/a404.pdf ER - TY - GEN A1 - Klein, Marten A1 - Kerstein, Alan R. A1 - Schmidt, Heiko T1 - Stochastic modeling of transient boundary layers in high-Rayleigh-number thermal convection T2 - 25th International Congress of Theoretical and Applied Mechanics (ICTAM 20+1) N2 - One-dimensional turbulence (ODT) modeling is used to investigate the boundary layer in high-Rayleigh-number thermal convection for a notionally infinite horizontal layer of fluid. The model formulation distinguishes between turbulent advection, which is modeled by a stochastic process, and deterministic molecular diffusion to capture relevant vertical transport processes (including counter-gradient fluxes). For this study, statistical homogenization is applied to the two horizontal dimensions so that we use ODT as stand-alone tool. We show that the model yields mean and fluctuation temperature profiles that are in several respects consistent with available reference data. Furthermore, the profile of a surrogate for the fluctuation velocity is reminiscent of canonical wall turbulence. KW - one-dimensional turbulence KW - thermal convection KW - turbulent boundary layer Y1 - 2020 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Klein_2020_ODT-RBC_ICTAM20+1.pdf ER - TY - GEN A1 - Klein, Marten A1 - Schmidt, Heiko A1 - Kerstein, Alan R. T1 - Transition to the ultimate regime in a stochastic model for thermal convection with internal sources Y1 - 2021 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Klein_poster_ipam21.pdf CY - IPAM Workshop: Transport and Mixing in Complex and Turbulent Flows (CTF2021), University of California, Los Angeles, CA, USA ER - TY - GEN A1 - Medina Méndez, Juan Ali A1 - Klein, Marten A1 - Schmidt, Heiko T1 - Map-based stochastic methods for accurate modeling of turbulent transport: towards poly-dispersed engineering flows T2 - Jahrestreffen der ProcessNet Fachgruppen Mehrphasenstömung (MPH) und Computational Fluid Dynamics (CFD) Y1 - 2021 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Medina_2020_ODTProcessNet2021.pdf CY - Cottbus ER - TY - GEN A1 - Klein, Marten A1 - Schmidt, Heiko A1 - Lignell, David O. T1 - Map-based modeling of high-Ra turbulent convection in planar and spherical geometries T2 - Conference on Modelling Fluid Flow 2018 (CMFF'18) N2 - Turbulent convection is important in many technological and geophysical applications. A model problem for such flows is Rayleigh-Bénard (RB) convection. The classical RB setup is a fluid- filled box with a heated bottom and cooled top. For geophysical applications, the spherical geometry of the confinement is sometimes important (e.g. in mantle convection). This is addressed by a spherical annulus configuration in which fluid is confined between an inner hot and an outer cold sphere. In this case, the gravity field is radial and its strength can also vary with the radius. Numerical simulations of RB convection are challenging because of the high Rayleigh numbers (Ra) observed in applications. 3-D direct simulations have been performed up to Ra ~ 10^(12), but even larger values of Ra are relevant. Hence modeling is needed if one wishes to increase the accessible Rayleigh number limit within the considerable future. The difficulty is that gradient-diffusion approaches do not allow for scale interactions, which can be crucial for the dynamics of the flow and the resulting heat transfer. In order to make such simulations feasible we make use of a different modeling strategy, the so-called One-Dimensional Turbulence (ODT). ODT resolves all scales of the flow along a notional line of sight, but reduces cost by assuming statistical homogeneity of the flow in the off-line directions. Along the line, turbulent advection is modeled by discrete mapping events, which mimic the effect of turbulent stirring. These events are stochastically sampled with highest probability where shear and buoyancy yield net available energy in analogy to real turbulence. In the talk, we evaluate ODT results against available reference data (e.g. flow statistics, heat transfer) using a new and fully adaptive version of ODT. This new version allows to simulate turbulent convection in spherical geometry. We address this by discussing the effects of radius ratio and radius-dependent gravity. KW - stochastic turbulence modeling KW - one-dimensional turbulence KW - heat transfer KW - high Rayleigh number KW - spherical shell convection KW - turbulent thermal convection Y1 - 2018 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Klein_cmff18_abstract.pdf ER - TY - GEN A1 - Klein, Marten A1 - Schmidt, Heiko T1 - Investigating Rayleigh-Bénard convection at low Prandtl numbers using one-dimensional turbulence modeling T2 - Proc. of the 11th International Symposium on Turbulence and Shear Flow Phenomena (TSFP11), Southampton, UK, July 30 to August 2, 2019 N2 - We numerically investigate the heat transfer in turbulent Rayleigh–Bénard convection at two Prandtl numbers, Pr = 0.021 and 0.7, respectively. Small-scale resolving simulations up to the Rayleigh numbers Ra = 10^(13) (Pr = 0.021) and 10^(16) (Pr = 0.7) are made feasible by utilizing the stochastic, one-dimensional turbulence (ODT) model. Present ODT simulations exhibit effective Nusselt number Nu scalings of the form Nu ∼ Ra^γ. At low Rayleigh numbers, ODT yields a scaling exponent of γ = 0.29 (Pr = 0.021) and 0.32 (Pr = 0.7), respectively. Both values are systematically, but just slightly, overestimating available reference data. At high Rayleigh numbers, present ODT results exhibit an increase of the exponent to γ = 0.32 (Pr = 0.021) and 0.36 (Pr = 0.7), respectively. Our preliminary results suggest that ODT might be able to capture a transition from the classical to the ultimate state of convection in terms of (i) critical Rayleigh number and (ii) increase of γ. KW - stochastic turbulence modeling KW - one-dimensional turbulence KW - turbulent thermal convection KW - high Rayleigh number Y1 - 2019 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Klein_2019_tsfp11_v2.pdf SP - 1 EP - 3 ER - TY - GEN A1 - Medina Méndez, Juan Ali A1 - Klein, Marten A1 - Schmidt, Heiko T1 - The One-Dimensional Turbulence Aspects of Internal Forced Convective Flows T2 - 14th WCCM-ECCOMAS Congress 2020 N2 - We present an overview of issues for the modeling of internal forced convective flows with the One-Dimensional Turbulence (ODT) model. Results of recent research as well as prospective research issues are presented for statistically streamwise homogeneous flows and streamwise inhomogeneous mixed convective flows. The results illustrate the capabilities of the model to evaluate and bring insight into a wide range of physical phenomena in the field of convective flows. Nonetheless, as a model, ODT is best suited for the evaluation of asymptotically turbulent flows, i.e., away from laminar regimes. KW - one-dimensional turbulence KW - stochastic turbulence modeling KW - turbulent drag KW - internal flow KW - heat transfer Y1 - 2021 UR - https://www.scipedia.com/public/Mendez_et_al_2021a U6 - https://doi.org/10.23967/wccm-eccomas.2020.338 SP - 1 EP - 12 PB - Scipedia ER - TY - GEN A1 - Klein, Marten A1 - Zenker, Christian A1 - Hertha, Katja A1 - Schmidt, Heiko T1 - Modeling One and Two Passive Scalar Mixing in Turbulent Jets Using One-Dimensional Turbulence T2 - 14th WCCM-ECCOMAS Congress 2020 N2 - Turbulent mixing of two passive scalars is investigated in a constant-property jets using stochastic one-dimensional turbulence (ODT). Scalars are separately injected by a central round and a surrounding annular jet that issue into a uniform co-flow of low velocity. These scalars are transported downstream and dispersed in radial direction by turbulent advection and molecular diffusion. The jet as well as the turbulent inflow are numerically simulated with ODT as stand-alone tool using a temporal (T-ODT) and spatial (S-ODT) formulation. We show that ODT captures key properties of the turbulent mixing for one scalar by performing individual scalar statistics and for two scalars by computation of joint probabilities. Some limitations of the one-dimensional modeling approach are also discussed. KW - one-dimensional turbulence KW - stochastic turbulence modeling KW - turbulent mixing KW - round jet KW - passive scalars Y1 - 2021 UR - https://www.scipedia.com/public/Klein_et_al_2021a U6 - https://doi.org/10.23967/wccm-eccomas.2020.205 SP - 1 EP - 12 PB - Scipedia ER - TY - GEN A1 - Klein, Marten A1 - Schmidt, Heiko T1 - Towards a stochastic model for electrohydrodynamic turbulence with application to electrolytes T2 - 91st Annual Meeting of GAMM 2020@21 N2 - We investigate turbulent electrohydrodynamic (EHD) Couette flows of dilute electrolytes and how they are affected by a prescribed electric field. In this canonical problem, molecular diffusion and electric drift currents can interact with turbulence which yields intricate dynamics down to the Kolmogorov and Batchelor scales that need to be resolved. The electrolytes considered have neutral bulk charge and consist of two independent, positive and negative, ion species with the same valence and mobility. The top wall of the set-up is moving and held at a different voltage relative to the bottom one. Resolution requirements and numerical feasibility are addressed by utilizing the stochastic one-dimensional turbulence (ODT) model as stand-alone tool in order to resolve all relevant scales of the flow for a dimensionally reduced setting. Deterministic diffusion and charge-carrier drift are directly resolved, whereas the effects of turbulent advection and pressure fluctuations are modeled by a stochastic process that operates along the wall-normal ODT domain. For the hydrodynamic and low Schmidt number EHD regime, ODT reasonably captures and extrapolates relevant leading-order boundary-layer properties of reference direct numerical simulations (DNS). For the high Schmidt number EHD regime, the model predicts notable interactions between turbulence and elektrokinetics only for large enough Reynolds numbers that manifests itself by a significant increase of the turbulent drag. Present ODT results suggests that the origin of this effect is related to the time-scale separation of convective versus electric drift and molecular transport processes transport across the boundary layer. In the talk, we will address the model formulation and its application to EHD Couette flow. Additionally, we will comment on the representation of electrokinetics and hydro-dynamics for the selected set-up. Finally, we will discuss the flow regimes in terms of skin friction drag and flow profiles with an eye also on electric variables and time scales. KW - one-dimensional turbulence KW - stochastic turbulence modeling KW - EHD turbulence KW - channel flow KW - electrolyte flow Y1 - 2021 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Klein_2021_elco_GAMM_abstract.pdf UR - https://hessenbox.uni-kassel.de/dl/fi226HzF3AJV3g4LFWM4fWE6/daily_program_2020.pdf?inline ER - TY - GEN A1 - Klein, Marten A1 - Schmidt, Heiko T1 - Stochastic modeling of transient neutral and stably-stratified Ekman boundary layers T2 - 91st Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM) - PAMM, Proceedings in Applied Mathematics and Mechanics N2 - Turbulence is a transient phenomenon in atmospheric boundary layers. These transients occur often due to surface temperature variations (e.g. due to diurnal forcing) that directly influence the near-surface flow by local stratification effects. Relevant dynamical and transport processes occur on a scale of meters near the surface which is a standing challenge for numerical weather and climate prediction. Here we investigate neutral and stably-stratified Ekman flows as a canonical problem for the night-time atmospheric boundary layer over flat terrain. The set-up used consists of an incompressible fluid over a smooth horizontal no-slip wall in a rotating frame of reference. The bulk flow is in geostrophic balance and acts as momentum source. In the case of stable stratification, temperature is prescribed as sudden cooling on a fully-developed turbulent neutrally-stratified Ekman boundary layer. When the stratification is weak, the temperature behaves like a passive scalar, but when it is strong, turbulence may locally disappear. Transient simulations across a relevant range of Reynolds and Froude numbers are made feasible by utilizing the stochastic one-dimensional turbulence (ODT) model. ODT aims to resolve vertical (wall-normal) transport processes on all relevant scales for a one-dimensional domain. Deterministic molecular diffusion and Coriolis forces are directly resolved, whereas turbulent advection is modeled by a stochastic process. The model obeys several relevant physical principles as, for example, Richardson’s 1/4 law of stratified turbulence. Preliminary results suggest that the stand-alone model generally captures Reynolds (turbulence) and Froude number (stratification) effects when stratification is weak. For low Froude number (strong stratification), these results indicate that the model tends to overestimate turbulence effects near the surface unless stratification becomes so strong that near-surface turbulence is energetically prohibited. In the talk, we will address the model formulation and its application to Ekman flow. We will show and discuss model results for surface fluxes, boundary-layer profiles, and corresponding fluctuation statistics. In addition, we will discuss stratification effects and comment on their representation in the model. KW - one-dimensional turbulence KW - stochastic turbulence modeling KW - atmospheric boundary layer KW - rotating flow KW - stratified flow Y1 - 2021 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Klein_2021_Ekman_GAMM_abstract.pdf U6 - https://doi.org/10.1002/pamm.202000127 SN - 1617-7061 VL - 20 IS - 1 ER - TY - GEN A1 - Klein, Marten A1 - Schmidt, Heiko A1 - Kerstein, Alan R. T1 - Transition to the ultimate regime in a stochastic model for radiatively driven turbulent convection T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft - BPCPPDYSOE21 KW - stochastic turbulence modeling KW - turbulent thermal convection KW - one-dimensional turbulence KW - heat transfer Y1 - 2021 UR - https://www.dpg-verhandlungen.de/year/2021/conference/bpcppdysoe/part/dy/session/2/contribution/1?lang=en ER - TY - CHAP A1 - Klein, Marten A1 - Schmidt, Heiko ED - Dillmann, Andreas ED - Heller, Gerd ED - Krämer, Ewald ED - Wagner, Claus T1 - Stochastic Modeling of Passive Scalars in Turbulent Channel Flows: Predictive Capabilities of One-Dimensional Turbulence T2 - New Results in Numerical and Experimental Fluid Mechanics XIII N2 - Numerical simulations of passive scalars in turbulent channel flows up to friction Reynolds number Reτ = 5200 and Schmidt number Sc = 2000 are performed by utilizing the stochastic one-dimensional turbulence (ODT) model as stand-alone tool. The model is calibrated once for the turbulent velocity boundary layer at Reτ = 5200 so that the passive scalar is a model prediction. ODT is able to reproduce with reasonable accuracy the scaling regimes of the scalar transfer and locally resolve the boundary layer structure. Albeit the model is unable to capture the emerging dissimilarity of near-wall scalar and momentum transport for high Sc, it can economically and accurately represent fluctuating wall-normal fluxes. KW - boundary layers KW - one-dimensional turbulence KW - passive scalar KW - turbulent channel flow Y1 - 2021 UR - https://link.springer.com/chapter/10.1007/978-3-030-79561-0_5 SN - 978-3-030-79561-0 U6 - https://doi.org/10.1007/978-3-030-79561-0_5 SP - 47 EP - 57 PB - Springer International Publishing CY - Cham ER - TY - GEN A1 - Klein, Marten A1 - Schmidt, Heiko A1 - Kerstein, Alan R. T1 - Transition to the ultimate regime in a stochasticmodel for thermal convection with internal sources N2 - It is well established that heat transfer in turbulent Rayleigh–Bénard convection and angular momentum transfer in turbulent Taylor–Couette flow are similar in nature. This similarity manifests itself by isomorphic scaling laws for corresponding flow regimes. However, it is not clear at present if this similarity extends to flows with internal sources and different types of boundary conditions. Internal sources may occur, for example, due to radiative heating in dry or condensation in moist convection, or due to internal wave breaking and mean flow excitation in rotating Taylor–Couette-like flows. In this study, heat transfer in radiatively-driven turbulent Rayleigh–Bénard convection is investigated using the stochastic one-dimensional-turbulence model (ODT). A Boussinesq fluid of Prandtl number 1 is confined between two horizontal adiabatic no-slip walls that are located at z = 0 and H, respectively. The fluid is exposed to constant background gravity that points in vertical (−z) direction. A flow is driven by radiative heating from below yielding the local heating rate Q(z) = (P/l) exp(−z/l), where P is the prescribed mean total heat flux and l the absorption length that controls the thermal boundary layer thickness. ODT resolves all relevant scales of the flow, including molecular-diffusive scales, along a vertical one-dimensional domain, whereas stochastically sampled eddy events represent the effects of turbulent advection. ODT results reproduce and extrapolate available reference experiments of Lepot et al. (Proc. Natl. Acad. Sci. USA, 115, 2018, pp. 8937–8941) and Bouillaut et al. (J. Fluid Mech., 861, 2019, R5) in particular capturing the turbulent transition from the classical to the ‘ultimate’ regime. For these regimes, the exponent values in N u ∼ Ra^p scaling are found to be p ≈ 0.33 and p ≈ 0.55, respectively, in agreement with measured values. Joint probabilities of turbulent eddy size and location suggest that the regime transition is associated with a suppression of small-scale near-wall turbulent motions. The latter observation is found consistent with recent direct numerical simulations of heat transfer between permeable walls (Kawano et al., J. Fluid Mech., 914, 2021, A13). KW - one-dimensional turbulence KW - turbulent thermal convection KW - heat transfer KW - high Rayleigh number Y1 - 2021 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Klein_poster_ictw21.pdf UR - https://www.b-tu.de/media/video/Transition-to-the-ultimate-regime-in-a-stochastic-model-for-thermal-convection-with-internal-sources/52aa69a52b8ab3ef29cc1d8bf9f20243 UR - https://pof.tnw.utwente.nl/ictw/schedule.html ER - TY - GEN A1 - Klein, Marten A1 - Zenker, Christian A1 - Schmidt, Heiko T1 - Map-based stochastic modeling of turbulent mixing in transient shear flows T2 - MATH+ CECAM Discussion Meeting on Generalized Langevin Equations N2 - Map-based stochastic modeling distinguishes molecular-diffusive from turbulent-advective transport processes in fluid flows. In the one-dimensional turbulence (ODT) model, a stochastic point process with energetically constrained rejection sampling of discrete eddy events is used to economically model the effects of turbulence on all relevant scales of the flow. Here I will discuss the model formulation and its application to passive scalar mixing in a confined jet. [1] M. Klein, C. Zenker, H. Schmidt (2019) Chem. Eng. Sci. 204:186-202 KW - one-dimensional turbulence KW - stochastic modeling KW - passive scalar KW - turbulent mixing Y1 - 2021 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Klein_abstract_public_cecam21.pdf UR - https://www.b-tu.de/media/video/Map-based-stochastic-modeling-of-turbulent-mixing-in-transient-shear-flows/5f7312768f6bcce987ed801635dcdc07 UR - https://www.cecam.org/workshop-details/1086 UR - https://www.sciencedirect.com/science/article/pii/S0009250919303896?via%3Dihub ER - TY - GEN A1 - Klein, Marten A1 - Schmidt, Heiko A1 - Kerstein, Alan R. T1 - Stochastic modeling of transient boundary layers in high-Rayleigh-number thermal convection, 25th International Congress of Theoretical and Applied Mechanics (ICTAM 20+1) N2 - One-dimensional turbulence (ODT) modeling is used to investigate the boundary layer in high-Rayleigh-number thermal convection for a notionally infinite horizontal layer of fluid. The model formulation distinguishes between turbulent advection, which is modeled by a stochastic process, and deterministic molecular diffusion to capture relevant vertical transport processes (including counter-gradient fluxes). For this study, statistical homogenization is applied to the two horizontal dimensions so that we use ODT as stand-alone tool. We show that the model yields mean and fluctuation temperature profiles that are in several respects consistent with available reference data. Furthermore, the profile of a surrogate for the fluctuation velocity is reminiscent of canonical wall turbulence. Y1 - 2021 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Klein_poster_ictam21.pdf UR - https://www.b-tu.de/media/video/Stochastic-modeling-of-transient-boundary-layers-in-high-Rayleigh-number-thermal-convection/f511d6b395472dc729543db3aa02dbc9 UR - https://www.ictam2020.org/assets/pdf/ICTAM2021-Fulllist-26-08.pdf ER - TY - GEN A1 - Klein, Marten A1 - Lignell, David O. A1 - Schmidt, Heiko T1 - Stochastic modeling of transient surface scalar and momentum fluxes in turbulent boundary layers T2 - EMS Annual Meeting 2021, online, 6–10 Sep 2021, EMS2021-79 N2 - Turbulence is ubiquitous in atmospheric boundary layers and manifests itself by transient transport processes on a range of scales. This range easily reaches down to less than a meter, which is smaller than the typical height of the first grid cell layer adjacent to the surface in numerical models for weather and climate prediction. In these models, the bulk-surface coupling plays an important role for the evolution of the atmosphere but it is not feasible to fully resolve it in applications. Hence, the overall quality of numerical weather and climate predictions crucially depends on the modeling of subfilter-scale transport processes near the surface. A standing challenge in this regard is the robust but efficient representation of transient and non-Fickian transport such as counter-gradient fluxes that arise from stratification and rotation effects. We address the issues mentioned above by utilizing a stochastic one-dimensional turbulence (ODT) model. For turbulent boundary layers, ODT aims to resolve the wall-normal transport processes on all relevant scales but only along a single one-dimensional domain (column) that is aligned with the vertical. Molecular diffusion and unbalanced Coriolis forces are directly resolved, whereas effects of turbulent advection and stratification are modeled by stochastically sampled sequence of mapping (eddy) events. Each of these events instantaneously modifies the flow profiles by a permutation of fluid parcels across a selected size interval. The model is of lower order but obeys fundamental conservation principles and Richardson's 1/4 law by construction. In this study, ODT is applied as stand-alone tool in order to investigate nondimensional control parameter dependencies of the scalar and momentum transport in turbulent channel, neutral, and stably-stratified Ekman flows up to (friction) Reynolds number Re = O(104). We demonstrate that ODT is able to capture the state-space statistics of transient surface fluxes as well as the boundary-layer structure and nondimensional control parameter dependencies of low-order flow statistics. Very good to reasonable agreement with available reference data is obtained for various observables using fixed model set-ups. We conclude that ODT is an economical turbulence model that is able to not only capture but also predict the wall-normal transport and surface fluxes in multiphysics turbulent boundary layers. KW - one-dimensional turbulence KW - stochastic modeling KW - Ekman flow KW - atmospheric boundary layer KW - roating and stratified fluids Y1 - 2021 UR - https://doi.org/10.5194/ems2021-79 UR - https://www.b-tu.de/media/video/Stochastic-modeling-of-transient-surface-scalar-and-momentum-fluxes-in-turbulent-boundary-layers/8c7baf58c040239649fb7c3b2212c1d5 U6 - https://doi.org/10.5194/ems2021-79 ER - TY - GEN A1 - Klein, Marten A1 - Schmidt, Heiko A1 - Lignell, David O. T1 - Stochastic modeling of transient surface scalar and momentum fluxes in turbulent boundary layers, EMS Annual Meeting 2021, online, 6–10 Sep 2021 KW - one-dimensional turbulence KW - stochastic modeling KW - Ekman flow KW - atmospheric boundary layer KW - roating and stratified fluids Y1 - 2021 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Klein_poster_ems21.pdf UR - https://www.b-tu.de/media/video/Stochastic-modeling-of-transient-surface-scalar-and-momentum-fluxes-in-turbulent-boundary-layers/8c7baf58c040239649fb7c3b2212c1d5 ER - TY - GEN A1 - Klein, Marten A1 - Schmidt, Heiko ED - Wagner, Claus T1 - Stochastic modeling and simulation of turbulent boundary layers in annular channel flow using one-dimensional turbulence T2 - STAB Jahresbericht 2021 N2 - In our contribution to the STAB workshop we will present the ODT model formulation with an emphasis on turbulent eddy energetics and map-based advection modeling in radial direction. After that, we will address ODT’s capabilities for simulation of turbulent boundary layers in planar and annular channel flows in terms of conventional turbulence statistics and bulk quantities. Last, we will address the effects of radius ratio and Reynolds number variations. KW - one-dimensional turbulence KW - stochastic modeling KW - spanwise curvature effects KW - radial momentum transport KW - boundary layers KW - coaxial pipe flow Y1 - 2021 UR - https://www.dlr.de/as/desktopdefault.aspx/tabid-128/268_read-1678/ UR - https://www.dlr.de/as/Portaldata/5/Resources/dokumente/veranstaltungen/stab_workshop/STAB-Jahresbericht-2021.pdf VL - 2021 SP - 39 EP - 40 PB - Deutsche Strömungsmechanische Arbeitsgemeinschaft, STAB CY - Göttingen ER - TY - GEN A1 - Klein, Marten A1 - Schmidt, Heiko A1 - Lignell, David O. T1 - Stochastic modeling of surface scalar-flux fluctuations in turbulent channel flow using one-dimensional turbulence T2 - International Journal of Heat and Fluid Flow N2 - Accurate and economical modeling of near-surface transport processes is a standing challenge for various engineering and atmospheric boundary-layer flows. In this paper, we address this challenge by utilizing a stochastic one-dimensional turbulence (ODT) model. ODT aims to resolve all relevant scales of a turbulent flow for a one-dimensional domain. Here ODT is applied to turbulent channel flow as stand-alone tool. The ODT domain is a wall-normal line that is aligned with the mean shear. The free model parameters are calibrated once for the turbulent velocity boundary layer at a fixed Reynolds number. After that, we use ODT to investigate the Schmidt (Sc), Reynolds (Re), and Peclet (Pe) number dependence of the scalar boundary-layer structure, turbulent fluctuations, transient surface fluxes, mixing, and transfer to a wall. We demonstrate that the model is able to resolve relevant wall-normal transport processes across the turbulent boundary layer and that it captures state-space statistics of the surface scalar-flux fluctuations. In addition, we show that the predicted mean scalar transfer, which is quantified by the Sherwood (Sh) number, self-consistently reproduces established scaling regimes and asymptotic relations. For high asymptotic Sc and Re, ODT results fall between the Dittus-Boelter, Sh ∼ Re^(4/5) Sc^(2/5), and Colburn, Sh ∼ Re^(4/5) Sc^(1/3), scalings but they are closer to the former. For finite Sc and Re, the model prediction reproduces the relation proposed by Schwertfirm and Manhart (Int. J. Heat Fluid Flow, vol. 28, pp. 1204-1214, 2007) that yields locally steeper effective scalings than any of the established asymptotic relations. The model extrapolates the scalar transfer to small asymptotic Sc ≪ Re_τ^(-1) (diffusive limit) with a functional form that has not been previously described. KW - one-dimensional turbulence KW - stochastic modeling KW - fluctuation modeling KW - passive scalar KW - scalar transfer KW - Schmidt number dependence KW - surface flux Y1 - 2021 UR - https://arxiv.org/abs/2111.15359 U6 - https://doi.org/10.1016/j.ijheatfluidflow.2021.108889 SN - 0142-727X VL - 93 (2022) SP - 1 EP - 19 ER - TY - GEN A1 - Klein, Marten A1 - Schmidt, Heiko T1 - Investigating Schmidt number effects in turbulent electroconvection using one-dimensional turbulence T2 - Proc. Appl. Math. Mech. N2 - Turbulent electroconvection denotes a fluctuating multiphysical flow in which hydrodynamics and electrokinetics interact on multiple scales. The dynamical processes at work are entangled down to the molecular-diffusive scales that are determined by the Schmidt (Sc) and Reynolds (Re) number. Turbulence properties are generally nonuniversal which leads to high numerical resolution requirements. We address the numerical challenges associated with accuracy and feasibility by utilizing a stochastic one-dimensional turbulence (ODT) model. Here, ODT is applied to turbulent Couette flow of dilute electrolytes as canonical problem for turbulent electroconvection. For Sc ⩾ O(10), ODT predicts an increase of the skin friction drag due to electrohydrodynamically (EHD) enhanced small-scale eddy production once the flow is sufficiently turbulent. KW - one-dimensional turbulence KW - stochastic modeling KW - turbulent Couette flow KW - electrohydrodynamic turbulence KW - Schmidt number effects KW - skin friction drag Y1 - 2021 U6 - https://doi.org/https://doi.org/10.1002/pamm.202100147 VL - 21 SP - 1 EP - 3 PB - Wiley CY - Weinheim ER - TY - GEN A1 - Klein, Marten A1 - Maier, Roland Erich A1 - Schmidt, Heiko T1 - Stochastic modeling of transient neutral and stably-stratified Ekman boundary layers T2 - Special Issue: 92nd Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM) N2 - Neutral and stably-stratified Ekman boundary layers (EBLs) are numerically investigated with a stochastic one-dimensional turbulence (ODT) model. EBLs achieve the bulk-surface coupling in Earth's atmosphere. They are numerically challenging due to transient and non-universal turbulence properties even at small scales. ODT addresses this problem by distinguishing turbulent-advective from molecular-diffusive transport processes for a vertical column along which all relevant scales of the flow are resolved. We demonstrate the model's capabilities for economical, accurate, and stratification regime independent simulation of EBLs for the wind-turning angle. ODT reproduces and extrapolates reference direct numerical simulation results consistent with observations. We conclude that ODT may be useful for modeling of atmospheric surface layers. KW - one-dimensional turbulence KW - stochastic modeling KW - turbulent Ekman flow KW - roating and stratified fluids KW - transition Y1 - 2021 U6 - https://doi.org/10.1002/pamm.202100146 VL - 21 SP - 1 EP - 3 PB - Wiley CY - Weinheim ER - TY - GEN A1 - Klein, Marten A1 - Freire, Livia S. A1 - Lignell, David O. A1 - Kerstein, Alan R. A1 - Schmidt, Heiko T1 - Ein stochastischer Ansatz zur Modellierung fluktuierender Oberflächenflüsse in turbulenten Grenzschichten T2 - Kurzfassungen der Meteorologentagung DACH N2 - Im Konferenzbeitrag wird auf die Formulierung des stochastischen Modells eingegangen und gezeigt, dass neben Scherspannungen auch Druck-, Coriolis- und Auftriebskräfte berücksichtigt werden können. Das Modell wird beispielhaft als unabhängiges, numerisches Werkzeug angewendet, um fluktuierende Oberflächenflüsse in turbulenten Kanalströmungen sowie stabilen und konvektiven Grenzschichten zu untersuchen. Es werden sowohl glatte, als auch raue bzw. bewachsene (poröse) Oberflächen betrachtet. Anhand neuer Ergebnisse wird demonstriert, dass der Modellansatz in der Lage ist, Referenzdaten zufriedenstellend zu reproduzieren und extrapolieren. Daneben werden aktuelle Arbeiten zur Kopplung des stochastischen Modellansatzes mit Large-Eddy-Simulationen vorgestellt. Es wird gezeigt, dass die stochastische Modellierung oberflächennaher, subgitterskaliger Schwankungen in der Lage ist, wandnahe Turbulenzspektren zu reproduzieren und den filterbasierten Modellfehler bei ansonsten fester Gitterauflösung zu verringern. KW - one-dimensional turbulence KW - stochastic modeling KW - turbulent boundary layer KW - turbulent convection KW - rotating and stratified flows Y1 - 2021 UR - https://meetingorganizer.copernicus.org/DACH2022/DACH2022-22.html U6 - https://doi.org/10.5194/dach2022-22 VL - 2022 SP - 1 EP - 1 PB - Copernicus ER - TY - GEN A1 - Sharma, Sparsh A1 - Klein, Marten A1 - Schmidt, Heiko T1 - Modelling turbulent jets at high-Reynolds number using one-dimensional turbulence T2 - AIAA AVIATION 2021 FORUM KW - stochastic modeling KW - turbulent round jet KW - one-dimensional turbulence Y1 - 2021 UR - https://arc.aiaa.org/doi/abs/10.2514/6.2021-2104 SN - 978-1-62410-610-1 U6 - https://doi.org/10.2514/6.2021-2104 PB - American Institute of Aeronautics and Astronautics, Inc. ER - TY - GEN A1 - Sharma, Sparsh A1 - Klein, Marten A1 - Schmidt, Heiko T1 - Features of far-downstream asymptotic velocity fluctuations in a round jet: A one-dimensional turbulence study T2 - Physics of Fluids KW - stochastic modeling KW - turbulent round jet KW - one-dimensional turbulence KW - jet similarity KW - multi-scale fluctuation modeling Y1 - 2022 UR - https://aip.scitation.org/doi/10.1063/5.0101270 U6 - https://doi.org/10.1063/5.0101270 SN - 1089-7666 VL - 34 IS - 8 ER - TY - GEN A1 - Klein, Marten A1 - Schmidt, Heiko T1 - Stochastic modeling of transient Ekman flow at arbitrary Reynolds number driven by horizontal bottom wall oscillation T2 - EMS Annual Meeting 2022, Abstracts KW - stochastic modeling KW - one-dimensional turbulence KW - rotating boundary layers KW - intermittency Y1 - 2022 U6 - https://doi.org/10.5194/ems2022-617 VL - 19 PB - Copernicus CY - Bonn, Germany ER - TY - GEN A1 - Tsai, Pei-Yun A1 - Schmidt, Heiko A1 - Klein, Marten T1 - Modeling simultaneous momentum and passive scalar transfer in turbulent annular Poiseuille flow T2 - 92nd Annual Meeting of GAMM KW - stochastic modeling KW - one-dimensional turbulence KW - heat and mass transfer KW - skin friction drag KW - forced convection KW - spanwise wall curvature Y1 - 2022 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Klein_2022_coaxialPipe_GAMM_abstract.pdf UR - https://jahrestagung.gamm-ev.de/wp-content/uploads/2022/08/Daily_Program_Web.pdf PB - Gesellschaft für angewandte Mathematik und Mechanik e.V. CY - Aachen, Germany ER - TY - GEN A1 - Klein, Marten A1 - Tsai, Pei-Yun A1 - Schmidt, Heiko T1 - Stochastic modeling of heat and momentum transfer in annular pipe flow: A one-dimensional turbulence study with comparison to DNS and LES T2 - STAB Jahresbericht 2022 KW - stochastic modeling KW - one-dimensional turbulence KW - heat and mass transfer KW - turbulent Poiseuille flow KW - large-eddy simulation Y1 - 2022 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Klein_2022_STAB_abstract.pdf UR - https://www.dlr.de/as/desktopdefault.aspx/tabid-128/268_read-1678/ UR - https://www.dlr.de/as/Portaldata/5/Resources/dokumente/veranstaltungen/stab_workshop/Jahresbericht2022.pdf VL - 23 PB - Deutsche Strömungsmechanische Arbeitsgemeinschaft (STAB) CY - Göttingen, Germany ER - TY - GEN A1 - Klein, Marten A1 - Medina Méndez, Juan Alí A1 - Schmidt, Heiko T1 - Modeling electrohydrodynamically enhanced drag in channel and pipe flows using one-dimensional turbulence T2 - Conference on Modelling Fluid Flow (CMFF’22) KW - stochastic modeling KW - one-dimensional turbulence KW - turbulent drag enhancement KW - electrohydrodynamic turbulence KW - multiphysical boundary layers Y1 - 2022 UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Klein_cmff22_abstract_EHDdrag.pdf UR - https://www-docs.b-tu.de/fg-stroemungsmodellierung/public/Klein_cmff22_paper_submitted_EHDdrag.pdf UR - https://www.cmff.hu/pdf/FinalProgramme.pdf SP - 1 EP - 8 CY - Budapest, Hungary ER - TY - GEN A1 - Klein, Marten A1 - Medina Méndez, Juan Alí A1 - Schmidt, Heiko ED - Vad, Janos T1 - Modeling electrohydrodynamically enhanced drag in channel and pipe flows using One-Dimensional Turbulenc T2 - Proceedings of the Conference on Modelling Fluid Flow (CMFF’22) N2 - The joint modeling of flow hydrodynamics and electrokinetics is a relatively unexplored area of turbulent flow research. We address a lack of available models for electrohydrodynamic (EHD) turbulent flow utilizing a lower-order approach, the stochastic One-Dimensional Turbulence (ODT) model. ODT is constructed on the principles of the direct energy cascade of Navier–Stokes turbulence, with key emphasis on the accurate resolution of the small molecular transport scales within a notional line-of-sight. We investigate two canonical flow configurations to demonstrate the applicability of the model in the simulation of EHD flows. First, we investigate EHD effects in zero-pressure-gradient turbulent boundary layers by two-way coupled model application to plane Couette flow of a dilute electrolyte. Second, we apply the one-way coupled model to EHD-enhanced gas flow through a vertical pipe with an inner concentric electrode, where electric fields are generated by means of a corona discharge and the corresponding effect of a continuum ionic charge density field. KW - EHD turbulence KW - multiphysical boundary layers KW - one-dimensional turbulence KW - stochastic modeling KW - turbulent drag enhancement Y1 - 2022 UR - https://www.cmff.hu/pdf/CMFF22_Conference_Proceedings.pdf UR - https://www.cmff.hu/papers/CMFF22_Final_Paper_PDF_15.pdf SN - 978-963-421-881-4 SP - 82 EP - 91 PB - University of Technology and Economics, Department of Fluid Mechanics CY - Budapest, Hungary 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 -