@misc{SharmaGeyerSarradjetal., author = {Sharma, Sparsh and Geyer, Thomas and Sarradj, Ennes and Schmidt, Heiko}, title = {Numerical investigation of noise generation by rod-airfoil configuration using DES (SU2) and the FW-H analogy}, series = {25th AIAA/CEAS Aeroacoustics Conference 2019, Delft, The Netherlands, 20 - 24 May 2019, (AIAA 2019-2400)}, journal = {25th AIAA/CEAS Aeroacoustics Conference 2019, Delft, The Netherlands, 20 - 24 May 2019, (AIAA 2019-2400)}, doi = {10.2514/6.2019-2400}, pages = {1 -- 17}, language = {en} } @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{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{StarickLignellSchmidt, author = {Starick, Tommy and Lignell, David O. and Schmidt, Heiko}, title = {One-Dimensional Turbulence Modelling of a Lifted Methane/Air Jet Flame in a Vitiated Coflow}, 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}, abstract = {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.}, language = {en} } @misc{MedinaMendezSchmidtRiebel, author = {Medina M{\´e}ndez, Juan Ali and Schmidt, Heiko and Riebel, Ulrich}, title = {Towards a One-Dimensional Turbulence Approach for Electrohydrodynamic Flows}, series = {11th International Symposium on Turbulence and Shear Flow Phenomena (TSFP11), Southampton, UK, July 30 to August 2, 2019}, journal = {11th International Symposium on Turbulence and Shear Flow Phenomena (TSFP11), Southampton, UK, July 30 to August 2, 2019}, pages = {6}, abstract = {The One-Dimensional Turbulence model is modified in this work for its application to a classical electrohydrodynamic (EHD) problem. Being the first study case, this work is focused on the influence of electrostatic fields and space charge on the velocity field inside a wire-plate Electrostatic Precipitator (ESP) with one-way-coupling dynamics. The study case is an attempt to replicate velocity profiles and Turbulent Kinetic Energy (TKE) budgets obtained in the Direct Numerical Simulation (DNS) carried out by Soldati and Banerjee (1998). Qualitative trends are confirmed in preliminary ODT results, thus showing the potential of the stochastic ODT modeling approach for other types of EHD flows.}, 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{KleinLignellSchmidt, author = {Klein, Marten and Lignell, David O. and Schmidt, Heiko}, title = {MS404: Map-based stochastic methods for accurate modeling of turbulent heat and mass transfer}, series = {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}, journal = {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}, pages = {1}, language = {en} } @misc{KleinKersteinSchmidt, author = {Klein, Marten and Kerstein, Alan R. and Schmidt, Heiko}, title = {Stochastic modeling of transient boundary layers in high-Rayleigh-number thermal convection}, series = {25th International Congress of Theoretical and Applied Mechanics (ICTAM 20+1)}, journal = {25th International Congress of Theoretical and Applied Mechanics (ICTAM 20+1)}, pages = {2}, abstract = {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.}, language = {en} } @misc{MedinaMendezSchmidtBacheretal., author = {Medina M{\´e}ndez, Juan Ali and Schmidt, Heiko and Bacher, Christian and Riebel, Ulrich}, title = {Electrohydrodynamic-enhanced internal pipe flows from a One-Dimensional Turbulence perspective}, series = {91st Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM)}, volume = {20}, journal = {91st Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM)}, number = {1}, publisher = {Wiley}, doi = {10.1002/pamm.202000132}, pages = {3}, language = {en} } @misc{RakhiSchmidt, author = {Rakhi, Rakhi and Schmidt, Heiko}, title = {Using a Stochastic One-Dimensional Turbulence model to study Incomporessible Spatially Developing Turbulent Boundary Layers}, 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{SharmaGeyerSarradjetal., author = {Sharma, Sparsh and Geyer, Thomas and Sarradj, Ennes and Schmidt, Heiko}, title = {Experimental validation of a lower-order model for leading-edge noise based on vortex method}, series = {27th AIAA/CEAS Aeroacoustics Conference 2021, Virtual Event, August 2 - 6 2021}, journal = {27th AIAA/CEAS Aeroacoustics Conference 2021, Virtual Event, August 2 - 6 2021}, doi = {10.2514/6.2021-2250}, language = {en} } @misc{KleinSchmidt, author = {Klein, Marten and Schmidt, Heiko}, title = {Investigating Schmidt number effects in turbulent electroconvection using one-dimensional turbulence}, series = {Proc. Appl. Math. Mech.}, volume = {21}, journal = {Proc. Appl. Math. Mech.}, publisher = {Wiley}, address = {Weinheim}, doi = {https://doi.org/10.1002/pamm.202100147}, pages = {1 -- 3}, abstract = {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.}, language = {en} } @misc{KleinMaierSchmidt, author = {Klein, Marten and Maier, Roland Erich and Schmidt, Heiko}, title = {Stochastic modeling of transient neutral and stably-stratified Ekman boundary layers}, series = {Special Issue: 92nd Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM)}, volume = {21}, journal = {Special Issue: 92nd Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM)}, publisher = {Wiley}, address = {Weinheim}, doi = {10.1002/pamm.202100146}, pages = {1 -- 3}, abstract = {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.}, language = {en} } @misc{MedinaMendezSchmidt, author = {Medina M{\´e}ndez, Juan Ali and Schmidt, Heiko}, title = {Towards the application of the One-Dimensional Turbulence model for the evaluation of collection efficiencies in wire-tube electrostatic precipitators}, series = {Proceedings in Applied Mathematics and Mechanics}, volume = {21}, journal = {Proceedings in Applied Mathematics and Mechanics}, number = {1}, issn = {1617-7061}, doi = {10.1002/pamm.202100220}, pages = {3}, language = {en} } @misc{KleinFreireLignelletal., author = {Klein, Marten and Freire, Livia S. and Lignell, David O. and Kerstein, Alan R. and Schmidt, Heiko}, title = {Ein stochastischer Ansatz zur Modellierung fluktuierender Oberfl{\"a}chenfl{\"u}sse in turbulenten Grenzschichten}, series = {Kurzfassungen der Meteorologentagung DACH}, volume = {2022}, journal = {Kurzfassungen der Meteorologentagung DACH}, publisher = {Copernicus}, doi = {10.5194/dach2022-22}, pages = {1 -- 1}, abstract = {Im Konferenzbeitrag wird auf die Formulierung des stochastischen Modells eingegangen und gezeigt, dass neben Scherspannungen auch Druck-, Coriolis- und Auftriebskr{\"a}fte ber{\"u}cksichtigt werden k{\"o}nnen. Das Modell wird beispielhaft als unabh{\"a}ngiges, numerisches Werkzeug angewendet, um fluktuierende Oberfl{\"a}chenfl{\"u}sse in turbulenten Kanalstr{\"o}mungen sowie stabilen und konvektiven Grenzschichten zu untersuchen. Es werden sowohl glatte, als auch raue bzw. bewachsene (por{\"o}se) Oberfl{\"a}chen 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 oberfl{\"a}chennaher, subgitterskaliger Schwankungen in der Lage ist, wandnahe Turbulenzspektren zu reproduzieren und den filterbasierten Modellfehler bei ansonsten fester Gitteraufl{\"o}sung zu verringern.}, language = {de} } @misc{SharmaKleinSchmidt, author = {Sharma, Sparsh and Klein, Marten and Schmidt, Heiko}, title = {Modelling turbulent jets at high-Reynolds number using one-dimensional turbulence}, series = {AIAA AVIATION 2021 FORUM}, journal = {AIAA AVIATION 2021 FORUM}, publisher = {American Institute of Aeronautics and Astronautics, Inc.}, isbn = {978-1-62410-610-1}, doi = {10.2514/6.2021-2104}, language = {en} } @misc{KleinSchmidt, author = {Klein, Marten and Schmidt, Heiko}, title = {Stochastic modeling of transient Ekman flow at arbitrary Reynolds number driven by horizontal bottom wall oscillation}, series = {EMS Annual Meeting 2022, Abstracts}, volume = {19}, journal = {EMS Annual Meeting 2022, Abstracts}, publisher = {Copernicus}, address = {Bonn, Germany}, doi = {10.5194/ems2022-617}, language = {en} } @misc{TsaiSchmidtKlein, author = {Tsai, Pei-Yun and Schmidt, Heiko and Klein, Marten}, title = {Modeling simultaneous momentum and passive scalar transfer in turbulent annular Poiseuille flow}, series = {92nd Annual Meeting of GAMM}, journal = {92nd Annual Meeting of GAMM}, publisher = {Gesellschaft f{\"u}r angewandte Mathematik und Mechanik e.V.}, address = {Aachen, Germany}, language = {en} } @misc{KleinTsaiSchmidt, author = {Klein, Marten and Tsai, Pei-Yun and Schmidt, Heiko}, title = {Stochastic modeling of heat and momentum transfer in annular pipe flow: A one-dimensional turbulence study with comparison to DNS and LES}, series = {STAB Jahresbericht 2022}, volume = {23}, journal = {STAB Jahresbericht 2022}, publisher = {Deutsche Str{\"o}mungsmechanische Arbeitsgemeinschaft (STAB)}, address = {G{\"o}ttingen, Germany}, language = {en} } @misc{KleinMedinaMendezSchmidt, author = {Klein, Marten and Medina M{\´e}ndez, Juan Al{\´i} and Schmidt, Heiko}, title = {Modeling electrohydrodynamically enhanced drag in channel and pipe flows using one-dimensional turbulence}, series = {Conference on Modelling Fluid Flow (CMFF'22)}, journal = {Conference on Modelling Fluid Flow (CMFF'22)}, address = {Budapest, Hungary}, pages = {1 -- 8}, language = {en} } @misc{KleinMedinaMendezSchmidt, author = {Klein, Marten and Medina M{\´e}ndez, Juan Al{\´i} and Schmidt, Heiko}, title = {Modeling electrohydrodynamically enhanced drag in channel and pipe flows using One-Dimensional Turbulenc}, series = {Proceedings of the Conference on Modelling Fluid Flow (CMFF'22)}, journal = {Proceedings of the Conference on Modelling Fluid Flow (CMFF'22)}, editor = {Vad, Janos}, publisher = {University of Technology and Economics, Department of Fluid Mechanics}, address = {Budapest, Hungary}, isbn = {978-963-421-881-4}, pages = {82 -- 91}, abstract = {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.}, language = {en} } @misc{KleinZenkerStaricketal., author = {Klein, Marten and Zenker, Christian and Starick, Tommy and Schmidt, Heiko}, title = {Stochastic modeling of three-scalar mixing in a coaxial jet using one-dimensional turbulence}, series = {12th International Symposium on Turbulence and Shear Flow Phenomena (TSFP12), Osaka, Japan (Online), July 19-22, 2022}, journal = {12th International Symposium on Turbulence and Shear Flow Phenomena (TSFP12), Osaka, Japan (Online), July 19-22, 2022}, pages = {1 -- 6}, abstract = {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.}, language = {en} } @misc{StarickBehrangLignelletal., author = {Starick, Tommy and Behrang, Masoomeh and Lignell, David O. and Schmidt, Heiko and Kerstein, Alan R.}, title = {Turbulent mixing simulation using the Hierarchical Parcel Swapping (HiPS) model}, series = {Proceedings of the Conference on Modelling Fluid Flow (CMFF'22)}, journal = {Proceedings of the Conference on Modelling Fluid Flow (CMFF'22)}, publisher = {Department of Fluid Mechanics, University of Technology and Economics}, address = {Budapest, Hungary}, isbn = {978-963-421-881-4}, pages = {1 -- 7}, language = {en} } @misc{MedinaMendezParraLafuenteSchmidt, author = {Medina M{\´e}ndez, Juan Al{\´i} and Parra Lafuente, Adri{\´a}n and Schmidt, Heiko}, title = {A volume-averaging and stochastic turbulence modeling framework for homogeneous roughness-induced drag in turbulent flows}, series = {Special Issue: 94th Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM)}, volume = {24}, journal = {Special Issue: 94th Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM)}, number = {3}, publisher = {Wiley}, issn = {1617-7061}, doi = {10.1002/pamm.202400136}, pages = {1 -- 13}, abstract = {The goal of this work is the formulation of a model for the parameterization of homogeneous roughness-induced drag in turbulent flow simulations. We characterize rough surfaces using their surface-area moments of roughness-peaks. Additionally, we consider a probabilistic self-similar power law distribution for the roughness heights, in such a way that an assumed set of discrete roughness elements can behave as a probabilistic fractal set. Upon these assumptions, the surface characterization is complete and yields wall-normal profiles of porosity, average roughness element diameter, and equivalent pore diameter of the roughness affected porous flow. The profiles are supplied to a (pore-based) Reynolds number and porosity-based drag parameterization for staggered cylinder arrays available in the literature, as well as a one-dimensional map-based turbulence model, the one-dimensional turbulence (ODT) model. The purpose of the latter is a way to provide the missing effects of the equivalent dispersion tensor in the porous flow close to the rough surface, as well as that of the nonlinear turbulent transport away from the wall. Simulations are then carried out in order to evaluate the effects of two different rough surfaces on a turbulent channel flow, comparing results with existing direct numerical simulation (DNS) data. Overall, reasonable agreement is obtained, which suggests that, by using the proposed model, it is possible to model the effects of rough surfaces on wall-bounded turbulent flows, without the explicit need of the full topological representation of the surface on the numerical domain. To that extent, one clear flow control application for the suggested approach would be that of drag-based surface optimization.}, language = {en} } @misc{MedinaMendezDorneanuSchmidtetal., author = {Medina M{\´e}ndez, Juan Al{\´i} and Dorneanu, Bogdan and Schmidt, Heiko and Arellano-Garc{\´i}a, Harvey}, title = {Revisiting homogeneous modeling with volume averaging theory: structured catalysts for steam reforming and CO2 methanation}, series = {Book of Abstracts XXVI Fluid Mechanics Conference (FMC 2024), Warsaw, Poland, September 10-13, 2024}, journal = {Book of Abstracts XXVI Fluid Mechanics Conference (FMC 2024), Warsaw, Poland, September 10-13, 2024}, publisher = {University of Technology}, address = {Warsaw}, pages = {2}, language = {en} } @misc{StarickSchmidt, author = {Starick, Tommy and Schmidt, Heiko}, title = {Investigation of turbulent mixing using a stochastic hierarchical parcel swapping mixing model}, series = {92nd Annual Meeting of GAMM}, journal = {92nd Annual Meeting of GAMM}, address = {Aachen, Germany}, pages = {1}, language = {en} } @misc{TsaiSchmidtKlein, author = {Tsai, Pei-Yun and Schmidt, Heiko and Klein, Marten}, title = {Modeling simultaneous momentum and passive scalar transfer in turbulent annular Poiseuille flow}, series = {Proceedings in applied mathematics and mechanics : PAMM}, volume = {22}, journal = {Proceedings in applied mathematics and mechanics : PAMM}, number = {1}, issn = {1617-7061}, doi = {10.1002/pamm.202200272}, abstract = {Simultaneous momentum and passive scalar transfer in weakly heated pressure-driven turbulent concentric annular pipe flow is numerically investigated using the cylindrical formulation of the stochastic one-dimensional turbulence (ODT) model,which is utilized here as standalone tool. In the present study, we focus on the model calibration for heated annular pipes based on recent reference direct numerical simulations (DNS) from Bagheri and Wang (Int. J. Heat Fluid Flow 86, 108725,2020; Phys. Fluids 33, 055131, 2021). It is shown that the model is able to individually capture scalar and momentum transfer, but not both equally well at the same time. We attribute this to less dissimilar scalar and momentum transport in the model at the low Reynolds number investigated. It is argued that the model prefers a fully developed turbulent state due to its construction. Nevertheless, it is demonstrated that ODT is able to reasonably capture the radial inner-outer asymmetry of the scalar and momentum boundary layers which yields better predictive capabilities than wall-function-based approaches.}, language = {en} } @misc{GlaweKleinSchmidt, author = {Glawe, Christoph and Klein, Marten and Schmidt, Heiko}, title = {Stochastic deconvolution of wall statistics in Reynolds-averaged Navier-Stokes simulations based on one-dimensional turbulence}, series = {Proceedings in applied mathematics and mechanics : PAMM}, volume = {23}, journal = {Proceedings in applied mathematics and mechanics : PAMM}, number = {3}, issn = {1617-7061}, doi = {10.1002/pamm.202300055}, pages = {9}, abstract = {Reynolds-averaged Navier-Stokes simulation (RaNS) is state-of-the-art for numerical analysis of complex flows at high Reynolds number. Standalone RaNS may yield a reasonable estimate of the wall-shear stress and turbulent drag if a proper wall-function is prescribed, but detailed turbulence statistics cannot be obtained, especially at the wall. This lack in modeling is addressed here by a stochastic deconvolution strategy based on a stochastic one-dimensional turbulence (ODT) model. Here, a one-way coupling strategy is proposed in which a forcing term is computed from the balanced RaNS solution that is in turn utilized in the ODT model. The temporally developing ODT solution exhibits turbulent perturbations but relaxes toward the local RaNS solution due to resolved molecular-diffusive processes. It is demonstrated that the approach is able to recover the distribution of positive wall-shear stress fluctuations in turbulent channel flow. When formulated as post-processing tool, it is suggested that RaNS can be enhanced by ODT providing economical means for local high-fidelity numerical modeling based on a low-fidelity flow solution.}, language = {en} } @misc{MedinaMendezSharmaSchmidtetal., author = {Medina M{\´e}ndez, Juan Ali and Sharma, Sparsh and Schmidt, Heiko and Klein, Marten}, title = {Toward the use of a reduced-order and stochastic turbulence model for assessment of far-field sound radiation: Low Mach number jet flows}, series = {Proceedings in Applied Mathematics and Mechanics}, volume = {23}, journal = {Proceedings in Applied Mathematics and Mechanics}, number = {3}, issn = {1617-7061}, doi = {10.1002/pamm.202300186}, pages = {9}, language = {en} } @misc{StarickSchmidt, author = {Starick, Tommy and Schmidt, Heiko}, title = {Stochastic map-based modeling of a lifted methane/air jet flame in a vitiated coflow}, series = {Proceedings of the Thirteenth International Symposium on Turbulence and Shear Flow Phenomena (TSFP13) (2024) Montreal}, volume = {2024}, journal = {Proceedings of the Thirteenth International Symposium on Turbulence and Shear Flow Phenomena (TSFP13) (2024) Montreal}, pages = {6}, language = {en} } @misc{KleinSchmidt, author = {Klein, Marten and Schmidt, Heiko}, title = {Capturing features of transient boundary layers with a map-based stochastic modeling approach}, publisher = {Copernicus GmbH}, doi = {10.5194/egusphere-egu24-15560}, pages = {2}, abstract = {Atmospheric boundary layers (ABLs) exhibit transient processes on various time and length scales, with a scale separation between the large-scale forcing and the small-scale response. Some crucial but standing challenges in modeling and simulation of ABL flows lie in the detailed representation of boundary layer turbulence (e.g. [1]). This includes intermittent and transient processes and the resulting turbulent and laminar response mechanisms. State-of-the-art subgrid-scale models utilize statistical closures for an averaged resolved flow state on the basis of the Monin-Obhukov similarity theory (MOST) to represent scalar fluxes and momentum fluxes (e.g. [2]). Fluctuations are not resolved in MOST. Instead, their ensemble effect is parameterized by the resolved large scales, neglecting backscatter from the unresolved small scales. Data-driven stochastic approaches aim to incorporate fluctuations and the spontaneous occurrence of instabilities, but at the expense of ad hoc forcings (e.g. [3]). The mentioned limitations can be removed by a physically compatible representation of turbulent fluctuations. This is addressed here by utilization of a map-based stochastic approach that is based on the one-dimensional turbulence (ODT) model [4]. ODT autonomously evolves vertical flow profiles for prescribed initial and boundary conditions, and physical forcings. The model captures turbulent cascade phenomenology and aims to resolve all relevant turbulent scales along a physical coordinate. Turbulent advection is modeled by a stochastically sampled sequence of spatial mapping events that punctuate the deterministic advancement due to viscous and Coriolis forces. The offered dynamical complexity removes the need for artificial forcings. In the contribution, key results from recent and ongoing studies related to the reduced-order modeling of ABL flows will be presented. First, surface scalar and momentum fluxes in turbulent channels are discussed emphasizing the correctly predicted inapplicability of the Reynolds analogy [5]. Second, the influence of system rotation and stratification is discussed for low-order velocity statistics and the participating turbulent scales [6,7]. Third, results for nonequilibrium conditions are presented for a transient ABL that exhibits turbulent bursts in response to an oscillatory geostrophic forcing [8]. Last, some preliminary results on the stochastic deconvolution of averaged data [9] will be presented focusing on the additional physical insight that is offered by the model. References [1] L. Mahrt. Annu. Rev. Fluid Mech. 46:23-45, 2014. [2] I. Stiperski, and M. Calaf. Phys. Rev. Lett. 130:124001, 2023. [3] V. Boyko, and N. Vercauteren. Q. J. R. Meteorol. Soc. 149(755):2125-2145, 2023. [4] A. R. Kerstein, and S. Wunsch. Bound.-Lay. Meteorol. 118:325-356, 2006. [5] M. Klein, H. Schmidt, and D. Lignell. Int. J. Heat Fluid Flow 93:108889, 2022. [6] M. Klein, and H. Schmidt. Adv. Sci. Res. 19:117-136, 2022. [7] L. S. Freire. Bound.-Lay. Meteorol. 184:25-43, 2022. [8] M. Klein, and H. Schmidt. Adv. Sci. Res. 20:55-64, 2023. [9] C. Glawe, M. Klein, and H. Schmidt. Proc. Appl. Math. Mech. 23:e202300055, 202}, language = {en} } @misc{PolasanapalliKleinSchmidt, author = {Polasanapalli, Sai Ravi Gupta and Klein, Marten and Schmidt, Heiko}, title = {Towards stochastic subgrid-scale modeling of turbulent thermal convection in an under-resolved off-lattice Boltzmann method}, series = {Proceedings in applied mathematics and mechanics : PAMM}, journal = {Proceedings in applied mathematics and mechanics : PAMM}, issn = {1617-7061}, doi = {10.1002/pamm.202300223}, pages = {1 -- 9}, abstract = {A characteristic-based Off-Lattice Boltzmann Method (OLBM) and a stochastic One-Dimensional Turbulence (ODT) model is utilized for numerical simulation of turbulent thermal convection. Standalone ODT results for low-order statistics are compared with those from various eddy-viscosity-based subgrid-scale models utilized in Large-Eddy Simulations (LES) with OLBM. The predictive capabilities of both approaches are discussed by comparison with available reference Direct Numerical Simulation (DNS) results. All turbulence models are able to predicted the mean temperature, but fail to fully capture fluctuations. While the OLBM aims to represent large-scale structures, it misses some constitutional small-scale fluctuations. By contrast, the reduced-order ODT model captures small-scale fluctuations in the vicinity of the wall, but cannot resolve the organized bulk flow. Here, the modeling capabilities of both OLBM and ODT as standalone tools are discussed. On this basis, a strategy for the incorporation of ODT as wall model in OLBM is suggested.}, language = {en} } @misc{KleinStarickZenkeretal., author = {Klein, Marten and Starick, Tommy and Zenker, Christian and Medina M{\´e}ndez, Juan Al{\´i} and Schmidt, Heiko}, title = {Reduced order stochastic modeling of turbulent mixing based on conservative baker's maps}, series = {Proceedings of the 14th International ERCOFTAC Symposium on Engineering Turbulence Modelling and Measurements (ETMM-14)}, journal = {Proceedings of the 14th International ERCOFTAC Symposium on Engineering Turbulence Modelling and Measurements (ETMM-14)}, publisher = {ERCOFTAC}, address = {Barcelona, Spain}, pages = {613 -- 618}, abstract = {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.}, language = {en} } @misc{MedinaMendezSchmidt, author = {Medina M{\´e}ndez, Juan Ali and Schmidt, Heiko}, title = {Towards the evaluation of heat and mass transfer in pipe flows with cocurrent falling films using One-Dimensional Turbulence}, series = {Proceedings in Applied Mathematics and Mechanics}, volume = {23}, journal = {Proceedings in Applied Mathematics and Mechanics}, number = {1}, address = {Aachen}, doi = {10.1002/pamm.202200271}, pages = {6}, language = {en} } @misc{MarinkovićMedinaSchoepsetal., author = {Marinković, Pavle and Medina, Juan A. and Sch{\"o}ps, Mark Simon and Klein, Marten and Schmidt, Heiko}, title = {Experiences from the bottom-up development of an object-oriented CFD solver with prospective hybrid turbulence model applications}, series = {Proceedings in Applied Mathematics and Mechanics}, volume = {25}, journal = {Proceedings in Applied Mathematics and Mechanics}, number = {1}, publisher = {Wiley}, issn = {1617-7061}, doi = {10.1002/pamm.202400190}, abstract = {In this work, we discuss recent experiences related to the development and enhancement of a hybrid stochastic computational fluid dynamics (CFD) solver, the C++ version of the Implicit/Explicit (IMEX) time-advancement algorithm used in the one-dimensional turbulence-based (ODT) large eddy simulation (LES) model, abbreviated as ODTLES. After being ported from Fortran 90, the current capabilities of the C++ code are restricted to the reproducibility of turbulent channel flow simulations with respect to the former Fortran code version that was able to achieve reasonable agreement with available reference direct numerical simulation (DNS) for low to moderate Reynolds number turbulent channel flows. This is far from satisfactory so that current efforts are centered on improving the solver code structure through comprehensive refactoring, robust unit testing, and strict adherence to code style guides, following the principles of Clean Code. We focus the discussion on a methodology to balance unit, regression, and integration testing, here for the LES component of the code. The objective is to frame a starting point that is relevant also for other CFD codes, irrespective of whether they utilize conventional or novel discretization or flow modeling approaches.}, language = {en} } @misc{MarinkovicMedinaKleinetal., author = {Marinkovic, Pavle and Medina, Juan and Klein, Marten and Schmidt, Heiko}, title = {Application of extended large-eddy simualtion (XLES) to turbulent channel flow}, series = {Proceedings in applied mathematics and mechanics : PAMM}, volume = {25 : special issue : 95th Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM)}, journal = {Proceedings in applied mathematics and mechanics : PAMM}, number = {2}, publisher = {Wiley}, address = {Weinheim}, issn = {1617-7061}, doi = {10.1002/pamm.70010}, pages = {1 -- 7}, abstract = {Extended large-eddy simulation (XLES) offers a promising middle ground between computational efficiency and predictive accuracy in turbulent flow simulations. By integrating the one-dimensional turbulence model as a stochastic subgrid-scale approach, XLES autonomously resolves turbulent microscales in a dimensionally reduced setting. Our implementation employs a coarse grid solely for pressure calculations, while three specialized high-resolution grids handle the turbulence dynamics. This multi-scale architecture reduces computational requirements by approximately two orders of magnitude compared to direct numerical simulation while maintaining comparable accuracy. Our results for turbulent channel flow at Reynolds number 395 demonstrate that XLES with a base resolution of just cells closely matches DNS reference data, vastly outperforming implicit LES using identical resolution and discretization schemes. This updated implementation of XLES, though still under active development, demonstrates significant potential for accurately simulating wall-bounded turbulent flows while substantially reducing computational requirements compared to traditional high-fidelity approaches.}, language = {en} } @misc{MarinkovicMedinaMendezKleinetal., author = {Marinkovic, Pavle and Medina M{\´e}ndez, Juan A. and Klein, Marten and Schmidt, Heiko}, title = {ODTLES : large-eddy simulation with autonomous stochastic subgrid-scale modeling applied to turbulent duct flow}, series = {Proceedings of the Conference on Modelling Fluid Flow CMFF'25}, journal = {Proceedings of the Conference on Modelling Fluid Flow CMFF'25}, publisher = {Budapest University of Technology and Economics}, address = {Budapest}, isbn = {978-615-112-002-6}, pages = {8}, abstract = {In this work, we discuss the application of the One-Dimensional Turbulence-based (very) Large-Eddy Simulation model, abbreviated as ODTLES, to turbulent duct flow. ODTLES is a multi-scale flow model in which an autonomous stochastic One-Dimensional Turbulence (ODT) model, capable of simulating the full bandwidth of time and length-scales in a 1-D domain, is supplemented with large-scale 3-D information coming from a very large eddy simulation (VLES) grid. ODTLES is more expensive than any other VLES, but could be cheaper than highly resolved LES or, naturally, than Direct Numerical Simulation (DNS). Unlike Reynolds-Averaged Navier-Stokes (RANS) and VLES, ODTLES does neither need a wall model, nor a damping function. The correct near-wall behavior is naturally obtained from one SGS ODT domain that is locally wall-normal. The proposed hybrid (3-D/1-D) approach allows the resolution of all relevant scales, modeling certain aspects of 3-D turbulence on the SGS scale. Here, turbulent duct flow is considered as an example, which poses a moderate challenge for traditional LES due to emerging secondary flows that manifest themselves by corner vortices that crucially depend on the accurate capturing of small and large scale motions. Preliminary results indicate a reasonable match with DNS for mean velocity profiles, although capturing secondary flow structures remains a challenge at this stage. Further refinements of the solver and modeling approach are ongoing to improve accuracy and predictive capabilities.}, language = {en} } @misc{PolasanapalliKleinSchmidt, author = {Polasanapalli, Sai Ravi Gupta and Klein, Marten and Schmidt, Heiko}, title = {Effects of wall slip on large-scale flow in turbulent Rayleigh-B{\´e}nard convection}, series = {Proceedings of the Conference on Modelling Fluid Flow CMFF'25}, journal = {Proceedings of the Conference on Modelling Fluid Flow CMFF'25}, publisher = {Budapest University of Technology and Economics}, address = {Budapest}, isbn = {978-615-112-002-6}, pages = {8}, abstract = {The current study investigates the effects of surface boundary conditions—no-slip, free-slip, and finite-slip-on flow dynamics and heat transfer inturbulent Rayleigh-B{\´e}nard (RB) convection for different Prandtl numbers. Using a three-dimensional lattice Boltzmann method (LBM) solver in direct numerical simulation (DNS) mode, simulations are performed for three Prandtl numbers Pr = 0.786, 4.38, 10 and two Rayleigh numbers Ra = 2 ×10^6 , 10^7 . The aim is to understand how surface conditions influence flow patterns, thermal mixing, and heat transfer efficiency in a cubic cavity with heated bottom and cooled top walls. Results show that free-slip conditions significantly enhance heat transfer, yielding higher Nusselt numbers due to thinner thermal boundary layers and stronger convective currents. In contrast, finite-slip conditions produce results similar to no-slip cases, indicating minimal impact for the slip lengths considered. The results demonstrate that surface boundary conditions play a role in modulating flow dynamics and heat transfer in RB convection.}, language = {en} } @misc{MedinaMendezKleinSchmidt, author = {Medina M{\´e}ndez, Juan Al{\´i} and Klein, Marten and Schmidt, Heiko}, title = {Fractal roughness representation in a stochastic one-dimensional turbulence modeling approach}, series = {Proceedings of the 13th International Symposium on Turbulence and Shear Flow Phenomena (TSFP13), Montr{\´e}al, Canada, June 25-28, 2024}, journal = {Proceedings of the 13th International Symposium on Turbulence and Shear Flow Phenomena (TSFP13), Montr{\´e}al, Canada, June 25-28, 2024}, pages = {1 -- 6}, language = {en} } @misc{StarickSchmidt, author = {Starick, Tommy and Schmidt, Heiko}, title = {Numerical investigation of a lifted methane/air jet flame using stochastic map-based turbulence modeling}, series = {Proceedings of the Conference on Modelling Fluid Flow CMFF'25}, journal = {Proceedings of the Conference on Modelling Fluid Flow CMFF'25}, publisher = {Department of Fluid Mechanics, Faculty of Mechanical Engineering, Budapest University of Technology and Economics}, address = {Budapest}, isbn = {978-615-112-002-6}, pages = {1 -- 8}, abstract = {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.}, language = {en} } @misc{TsaiYapKleinetal., author = {Tsai, Pei-Yun and Yap, Li Toong and Klein, Marten and Schmidt, Heiko}, title = {Investigation of radius ratio effects on velocity statistics in annular pipe flow using one-dimensional turbulence}, series = {Proceedings of the Conference on Modelling Fluid Flow CMFF'25}, journal = {Proceedings of the Conference on Modelling Fluid Flow CMFF'25}, publisher = {Budapest University of Technology and Economics}, address = {Budapest, Hungary}, isbn = {978-615-112-002-6}, pages = {304 -- 311}, language = {en} }