@misc{KleinSchmidt, author = {Klein, Marten and Schmidt, Heiko}, title = {Investigating the skin friction drag across electrolytes and electrical fields using one-dimensional turbulence modeling}, series = {European Drag Reduction and Flow Control Meeting, EDRFCM 2019, March 26-29 2019, Bad Herrenalb, Germany}, journal = {European Drag Reduction and Flow Control Meeting, EDRFCM 2019, March 26-29 2019, Bad Herrenalb, Germany}, pages = {1 -- 2}, language = {en} } @misc{KleinLignellSchmidt, author = {Klein, Marten and Lignell, David O. and Schmidt, Heiko}, title = {Stochastic modeling of temperature and velocity statistics in spherical-shell convection}, series = {Geophysical Research Abstracts, Vol. 21, EGU2019-2220}, journal = {Geophysical Research Abstracts, Vol. 21, EGU2019-2220}, pages = {1}, language = {en} } @misc{SchmidtKlein, author = {Schmidt, Heiko and Klein, Marten}, title = {Simulating neutrally and stably stratified turbulent Ekman flows with a stochastic turbulence model}, series = {Proc. of the 17th European Turbulence Conference (ETC17), 3-6 September 2019, Torino, Italy}, journal = {Proc. of the 17th European Turbulence Conference (ETC17), 3-6 September 2019, Torino, Italy}, pages = {1}, language = {en} } @misc{SommeriaVinczeFenyvesietal., author = {Sommeria, Joel and Vincze, Miklos and Fenyvesi, Nora and Klein, Marten and Viboud, Samuel and Ashkenazy, Yosef}, title = {Ekman layer resonance in an ocean-analog rotating tank experiment}, series = {17th European Turbulence Conference, Turin, 3 Sep 2019 - 6 Sep 2020}, journal = {17th European Turbulence Conference, Turin, 3 Sep 2019 - 6 Sep 2020}, language = {en} } @misc{KleinSchmidt, author = {Klein, Marten and Schmidt, Heiko}, title = {Investigating Rayleigh-B{\´e}nard convection at low Prandtl numbers using one-dimensional turbulence modeling}, series = {Proc. of the 11th International Symposium on Turbulence and Shear Flow Phenomena (TSFP11), Southampton, UK, July 30 to August 2, 2019}, journal = {Proc. of the 11th International Symposium on Turbulence and Shear Flow Phenomena (TSFP11), Southampton, UK, July 30 to August 2, 2019}, pages = {6}, language = {en} } @misc{KleinSchmidt, author = {Klein, Marten and Schmidt, Heiko}, title = {Investigating thermal convection at low Prandtl numbers using one-dimensional turbulence}, pages = {1}, language = {en} } @misc{KleinSchmidt, author = {Klein, Marten and Schmidt, Heiko}, title = {The transition to the ultimate regime of thermal convection from a stochastic one-dimensional turbulence perspective}, series = {arXiv}, journal = {arXiv}, pages = {1 -- 11}, language = {en} } @misc{RakhiKleinMedinaMendezetal., author = {Rakhi, Rakhi and Klein, Marten and Medina M{\´e}ndez, Juan Ali and Schmidt, Heiko}, title = {One-dimensional turbulence modelling of incompressible temporally developing turbulent boundary layers with comparison to DNS}, series = {Journal of Turbulence}, volume = {20}, journal = {Journal of Turbulence}, number = {8}, issn = {1468-5248}, doi = {10.1080/14685248.2019.1674859}, pages = {506 -- 543}, abstract = {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.}, language = {en} } @misc{StarickMedinaMendezKleinetal., author = {Starick, Tommy and Medina M{\´e}ndez, Juan Ali and Klein, Marten and Jozefik, Zoltan and Schmidt, Heiko}, title = {Zur j{\"u}ngsten Entwicklung in der Modellierung von turbulenten Verbrennungsprozessen mittels ODT}, series = {29. Deutscher Flammentag, 17-18 September 2019, Bochum, DE}, journal = {29. Deutscher Flammentag, 17-18 September 2019, Bochum, DE}, pages = {10}, abstract = {Die vorliegende Arbeit befasst sich mit den j{\"u}ngsten Entwicklungen und Anwendungen des One-Dimensional Turbulence (ODT) Modells auf reaktive Str{\"o}mungen. Bei ODT handelt es sich um ein stochastisches und abbildungsbasiertes Turbulenzmodell zur Simulation von turbulenten Str{\"o}mungen. In ODT wird das eindimensionale Rechengebiet als gedachte Linie durch das dreidimensionale Str{\"o}mungsfeld 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 ber{\"u}cksichtigt und vollst{\"a}ndig aufgel{\"o}st. In dieser Arbeit werden vorl{\"a}ufige ODT-Simulationsergebnisse von reaktiven Str{\"o}mungen f{\"u}r jeweilsein offenes und ein geschlossenes System vorgestellt. Essentielle Vorarbeiten, die die Vermischungeines passiven Skalars in einer planaren Strahld{\"u}se untersuchen, werden ebenfalls gezeigt. Beim offenen System handelt es sich um eine Methan/Luft Freistrahl-Flamme in einer umgebenden Str{\"o}mung aus heißen Verbrennungsgasen. Die Simulationsergebnisse werden zu Vergleichszweckenden Messungen von Cabra et al. gegen{\"u}bergestellt. Beim geschlossenen System wird die Selbstz{\"u}ndung 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 durchgef{\"u}hrten Studien konnte gezeigt werden, dass die mittels ODT erzeugten Statistiken eine beachtlich gute {\"U}bereinstimmung mit den Vergleichsdaten aufweisen. Im Hinblick auf die reduzierte Dimensionalit{\"a}t von ODT, die Qualit{\"a}tder erzielten Ergebnisse und die erforderliche Rechenleistung, stellt ODT ein attraktives Modell zurSimulation von turbulenten und reaktiven Str{\"o}mungen dar.}, language = {de} } @misc{StarickMedinaMendezKleinetal., author = {Starick, Tommy and Medina M{\´e}ndez, Juan Ali and Klein, Marten and Jozefik, Zoltan and Schmidt, Heiko}, title = {Zur j{\"u}ngsten Entwicklung in der Modellierung von turbulenten Verbrennungsprozessen mittels ODT}, pages = {1}, language = {de} } @misc{MedinaMendezKleinSchmidt, author = {Medina M{\´e}ndez, Juan Ali and Klein, Marten and Schmidt, Heiko}, title = {One-Dimensional Turbulence investigation of variable density effects due to heat transfer in a low Mach number internal air flow}, series = {International Journal of Heat and Fluid Flow}, volume = {80}, journal = {International Journal of Heat and Fluid Flow}, issn = {0142-727X}, doi = {10.1016/j.ijheatfluidflow.2019.108481}, pages = {19}, abstract = {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.}, language = {en} } @misc{KurganskySeeligKleinetal., author = {Kurgansky, Michael V. and Seelig, Torsten and Klein, Marten and Will, Andreas and Harlander, Uwe}, title = {Mean flow generation due to longitudinal librations of sidewalls of a rotating annulus}, series = {Geophysical \& Astrophysical Fluid Dynamics}, volume = {114}, journal = {Geophysical \& Astrophysical Fluid Dynamics}, number = {6}, issn = {1029-0419}, doi = {10.1080/03091929.2019.1692829}, pages = {762}, abstract = {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.}, language = {en} } @misc{KleinSchmidt, author = {Klein, Marten and Schmidt, Heiko}, title = {Stochastic modeling of passive scalars in turbulent channel flows}, series = {Jahresbericht 2020 zum Band: Notes on Numerical Fluid Mechanics and Multidisciplinary Design - New Results in Numerical and Experimental Fluid Mechanics XIII}, volume = {2020}, journal = {Jahresbericht 2020 zum Band: Notes on Numerical Fluid Mechanics and Multidisciplinary Design - New Results in Numerical and Experimental Fluid Mechanics XIII}, publisher = {Deutsche Str{\"o}mungsmechanische Arbeitsgemeinschaft, STAB}, address = {G{\"o}ttingen}, pages = {30 -- 31}, language = {en} } @misc{KleinSchmidt, author = {Klein, Marten and Schmidt, Heiko}, title = {Towards a stochastic model for electrohydrodynamic turbulence with application to electrolytes}, series = {Proceedings in Applied Mathematics and Mechanics}, volume = {2020}, journal = {Proceedings in Applied Mathematics and Mechanics}, number = {20}, publisher = {Wiley-VCH}, address = {Weinheim}, doi = {10.1002/pamm.202000128}, pages = {1 -- 2}, abstract = {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.}, language = {en} } @misc{SharmaKleinSchmidtetal., author = {Sharma, Sparsh and Klein, Marten and Schmidt, Heiko and Sarradj, Ennes}, title = {On a lower-order framework for jet noise prediction based on one-dimensional turbulence}, series = {arXiv}, journal = {arXiv}, pages = {1 -- 4}, abstract = {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.}, language = {en} } @misc{KleinSchmidt, author = {Klein, Marten and Schmidt, Heiko}, title = {Predictive modeling of passive scalar transfer to a wall using stochastic one-dimensional turbulence}, series = {arXiv}, journal = {arXiv}, pages = {8}, abstract = {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.}, language = {en} }