@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{HartmannKoehlerSchmidtetal., author = {Hartmann, Carsten and K{\"o}hler, Ekkehard and Schmidt, Heiko and Klein, Marten}, title = {Scientific computing LAB (SCL)}, series = {"Get Into Energy", BTU Cottbus-Senftenberg, ZHG Building, 1 Feb. 2023}, journal = {"Get Into Energy", BTU Cottbus-Senftenberg, ZHG Building, 1 Feb. 2023}, address = {Cottbus}, pages = {1}, abstract = {KEY COMPETENCE AND FOCUS • Development of numerical methods and algorithms for multi-energy systems • Multiscale and multiphysics modeling and simulation of P2X technologies • Stochastic simulation and efficient optimization of complex energy networks}, language = {en} } @misc{TsaiSchmidtKlein, author = {Tsai, Pei-Yun and Schmidt, Heiko and Klein, Marten}, title = {Stochastic modeling of heated turbulent coaxial pipe flow prescribing different thermal boundary conditions}, series = {18th European Turbulence Conference (ETC18), 4-6 September 2023, Valencia}, journal = {18th European Turbulence Conference (ETC18), 4-6 September 2023, Valencia}, address = {Valencia}, pages = {1}, language = {en} } @misc{MedinaMendezDorneanuSchmidtetal., author = {Medina M{\´e}ndez, Juan Ali 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 = {Journal of Physics: Conference Series}, volume = {2899/2024}, journal = {Journal of Physics: Conference Series}, issn = {1742-6596}, doi = {10.1088/1742-6596/2899/1/012004}, pages = {8}, abstract = {Progress in the modeling of structured catalysts is crucial for enhancing efficiency and scalability in industrial applications. Extensive research has investigated reactive flows over catalyst surfaces, covering chemical kinetics analysis and (direct) numerical simulations of the complete fluid flow in fixed-bed or structured catalysts. Nonetheless, this comes at a high computational cost. This study focuses on the homogeneous modeling of structured catalysts utilizing volume-averaging theory (VAT) as a more efficient method for representing the behaviour of such systems. We discuss modeling strategies for both 1-D and 3-D simulations. For steady 1-D flow simulations, we assess the influence of simplified gas chemical kinetics versus detailed surface chemistry, comparing with experimental data from the literature for a CO2 methanation processes. We also simulate 3-D flows of a steam reforming process, previously studied in the literature, using models which rely on different assumptions regarding the nature of the porous catalyst. Our findings reveal significant discrepancies based on different modeling assumptions, underscoring the necessity for accurate modeling of permeability and diffusivity tensors in homogeneous models.}, 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{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 = {Book of Abstracts 13th International Symposium on Turbulence and Shear Flow Phenomena (TSFP13), Montr{\´e}al, Canada, June 25-28, 2024}, journal = {Book of Abstracts 13th International Symposium on Turbulence and Shear Flow Phenomena (TSFP13), Montr{\´e}al, Canada, June 25-28, 2024}, address = {Montr{\´e}al, Canada}, pages = {3}, 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{NaikBuryeMedinaMendezKleinetal., author = {Naik Burye, Nishidh Shailesh and Medina M{\´e}ndez, Juan Al{\´i} and Klein, Marten and Schmidt, Heiko}, title = {Revisiting near-wall modeling of fully developed turbulent flow in concentric annuli}, series = {Jahresbericht 2024 zum 24. DGLR-Fachsymposium der STAB 13.-14. November 2024, Regensburg}, journal = {Jahresbericht 2024 zum 24. DGLR-Fachsymposium der STAB 13.-14. November 2024, Regensburg}, publisher = {Deutsche Str{\"o}mungsmechanische Arbeitsgemeinschaft, STAB}, address = {Regensburg}, pages = {174 -- 175}, language = {en} } @misc{PolasanapalliKleinSchmidt, author = {Polasanapalli, Sai Ravi Gupta and Klein, Marten and Schmidt, Heiko}, title = {Numerical study on the effects of transient pressure gradients on isothermal and heated pipe flows}, series = {94th Annual Meeting of the Association of Applied Mathematics and Mechanics March 18th-March 22nd, 2024 Magdeburg (Germany) : Book of Abstracts}, journal = {94th Annual Meeting of the Association of Applied Mathematics and Mechanics March 18th-March 22nd, 2024 Magdeburg (Germany) : Book of Abstracts}, address = {Magdeburg (Germany)}, pages = {227 -- 228}, language = {en} } @misc{JoshiMedinaMendezKleinetal., author = {Joshi, Abhishek and Medina Mendez, Juan Ali and Klein, Marten and Schmidt, Heiko}, title = {Simulating homogenous isotropic turbulence with deterministic and stochastic forcings using a one-dimensional turbulence model}, pages = {1}, abstract = {To understand the intermittency present in scalar fields we need to address the expense of current start-of-art DNS to probe the higher-order structure functions. These higher order moments become increasingly sensitive to increasing Reλ and much more prone to extreme events. Here, in this work, we investigate using a Reduced order model(ODT) to simulate Homogenous Isotropic turbulence as an initial step towards that goal by employing a linear forcing [1] proposed by Lundgren that is proportional to local and instantaneous velocity.}, language = {en} } @misc{MarinkovićMedinaMendezSchmidtetal., author = {Marinković, Pavle and Medina M{\´e}ndez, Juan Ali and Schmidt, Heiko and Klein, Marten}, title = {Ongoing development of a hybrid reduced order stochastic/LES solver for turbulent flows}, address = {Cottbus}, pages = {1}, language = {en} } @misc{TsaiSchmidtKlein, author = {Tsai, Pei-Yun and Schmidt, Heiko and Klein, Marten}, title = {Stochastic modeling and theoretical analysis of heated concentric coaxial pipes at low Prandtl number}, series = {94rd Annual Meeting of the International Association of Applied Mathematics and Mechanics, Book of Abstracts}, journal = {94rd Annual Meeting of the International Association of Applied Mathematics and Mechanics, Book of Abstracts}, publisher = {GAMM e.V.}, address = {Magdeburg}, pages = {11}, 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{KleinSchmidt, author = {Klein, Marten and Schmidt, Heiko}, title = {Time-resolved simulations of wind speed fluctuations across atmospheric boundary layers using a stochastic forward model}, series = {Verhandlungen der DPG Fr{\"u}hjahrstagung SMuK 2023}, journal = {Verhandlungen der DPG Fr{\"u}hjahrstagung SMuK 2023}, publisher = {Deutsche Physikalische Gesellschaft (DPG)}, address = {Dresden}, abstract = {Atmospheric boundary layers (ABLs) govern the atmosphere-surface coupling and are therefore of fundamental relevance for Earth's weather and climate system. Time-resolved numerical simulations of ABLs are challenging due to intricate interactions of inertial, Coriolis, buoyancy, and viscous forces on all relevant scales of the turbulent flow. Small-scale processes, albeit potentially nonuniversal, are typically not resolved due to cost constraints but modeled based on physically justified relations with the resolved scales, neglecting expensive backscatter. This lack in modeling is addressed here by utilizing a dimensionally reduced stochastic modeling approach. The model aims to reproduce turbulent cascade phenomenology by a stochastic process, respecting fundamental physical conservation principles. Momentary wind velocity and temperature profiles evolve autonomously in time for an ensemble of initial conditions. By comparison with available high-fidelity reference numerical simulations, reanalysis, and observations, it is shown that the model captures various relevant flow properties, exhibiting limitations mainly in a delayed relaminarization under very stable conditions. Forthcoming research aims to contribute to a better understanding of polar boundary layers, requiring predictive modeling capabilities, high resolution, and numerical efficiency to perform long-time simulations.}, language = {de} } @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{GaoSchmidtKleinetal., author = {Gao, Tianyun and Schmidt, Heiko and Klein, Marten and Liang, Jianhan and Sun, Mingbo and Chen, Chongpei and Guan, Qingdi}, title = {One-dimensional turbulence modeling of compressible flows. I. Conservative Eulerian formulation and application to supersonic channel flow}, series = {Physics of Fluids}, volume = {35}, journal = {Physics of Fluids}, number = {3}, issn = {1089-7666}, doi = {10.1063/5.0125514}, abstract = {Accurate but economical modeling of supersonic turbulent boundary layers is a standing challenge due to the intricate entanglement of temperature, density, and velocity fluctuations on top of the mean-field variation. Application of the van Driest transformation may describe well the mean state but cannot provide detailed flow information. This lack-in modeling coarse and fine-scale variability is addressed by the present study using a stochastic one-dimensional turbulence (ODT) model. ODT is a simulation methodology that represents the evolution of turbulent flow in a low-dimensional stochastic way. In this study, ODT is extended to fully compressible flows. An Eulerian framework and a conservative form of the governing equations serve as the basis of the compressible ODT model. Computational methods for statistical properties based on ODT realizations are also extended to compressible flows, and a comprehensive way of turbulent kinetic energy budget calculation based on compressible ODT is put forward for the first time. Two canonical direct numerical simulation cases of supersonic isothermal-wall channel flow at Mach numbers 1.5 and 3.0 with bulk Reynolds numbers 3000 and 4880, respectively, are used to validate the extended model. A rigorous numerical validation is presented, including the first-order mean statistics, the second-order root mean square statistics, and higher-order turbulent fluctuation statistics. In ODT results, both mean and root mean square profiles are accurately captured in the near-wall region. Near-wall temperature spectra reveal that temperature fluctuations are amplified at all turbulent scales as the effects of compressibility increase. This phenomenon is caused by intensified viscous heating at a higher Mach number, which is indicated by the steeper profiles of viscous turbulent kinetic energy budget terms in the very near-wall region. The low computational cost and predictive capabilities of ODT suggest that it is a promising approach for detailed modeling of highly turbulent compressible boundary layers. Furthermore, it is found that the ODT model requires a Mach-number-dependent increase in a viscous penalty parameter Z in wall-bounded turbulent flows to enable accurate capture of the buffer layer.}, language = {en} } @misc{GaoSchmidtKleinetal., author = {Gao, Tianyun and Schmidt, Heiko and Klein, Marten and Liang, Jianhan and Sun, Mingbo and Chen, Chongpei and Guan, Qingdi}, title = {One-dimensional turbulence modeling of compressible flows: II. Full compressible modification and application to shock-turbulence interaction}, series = {Physics of Fluids}, volume = {35}, journal = {Physics of Fluids}, number = {3}, issn = {1089-7666}, doi = {10.1063/5.0137435}, abstract = {One-dimensional turbulence (ODT) is a simulation methodology that represents the essential physics of three-dimensional turbulence through stochastic resolution of the full range of length and time scales on a one-dimensional domain. In the present study, full compressible modifications are incorporated into ODT methodology, based on an Eulerian framework and a conservative form of the governing equations. In the deterministic part of this approach, a shock capturing scheme is introduced for the first time. In the stochastic part, one-dimensional eddy events are modeled and sampled according to standard methods for compressible flow simulation. Time advancement adjustments are made to balance comparable time steps between the deterministic and stochastic parts in compressible flows. Canonical shock-turbulence interaction cases involving Richtmyer-Meshkov instability at Mach numbers 1.24, 1.5, and 1.98 are simulated to validate the extended model. The ODT results are compared with available reference data from large eddy simulations and laboratory experiments. The introduction of a shock capturing scheme significantly improves the performance of the ODT method, and the results for turbulent kinetic energy are qualitatively improved compared with those of a previous compressible Lagrangian ODT method [Jozefik et al., "Simulation of shock-turbulence interaction in non-reactive flow and in turbulent deflagration and detonation regimes using one-dimensional turbulence," Combust. Flame 164, 53 (2016)]. For the time evolution of profiles of the turbulent mixing zone width, ensemble-averaged density, and specific heat ratio, the new model also yields good to reasonable results. Furthermore, it is found that the viscous penalty parameter Z of the ODT model is insensitive to compressibility effects in turbulent flows without wall effects. A small value of Z is appropriate for turbulent flows with weak wall effects, and the parameter Z serves to suppress extremely small eddy events that would be dissipated instantly by viscosity.}, language = {en} } @misc{StarickSchmidt, author = {Starick, Tommy and Schmidt, Heiko}, title = {Investigation of turbulent mixing using a stochastic hierarchical parcel swapping mixing model}, 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.202200283}, abstract = {Turbulent mixing plays an important role in a variety of applications ranging from astrophysics to combustion and even pollutant dispersion. The Direct Numerical Simulation (DNS) that resolves all scales is not feasible for most engineering applications since the flow has a wide range of length and time scales, which yields extremely high resolution requirements. Large Eddy Simulations (LES) overcome this limitation by modeling the sub-grid scale effects. In transported Probability Density Function (PDF) methods, the key challenge is to develop an accurate mixing model. At this point, the Hierarchical Parcel-Swapping (HiPS) model, introduced by A.R. Kerstein [J. Stat. Phys. 153, 142-161 (2013)], is an attractive candidate. It is characterized by a computationally efficient representation of the effects of turbulence on a time-evolving structure of diffusive scalar fields. The interpretation of the diffusive scalar fields or a state space as a binary tree structure is an alternative approach compared to the most common mixing models. The characteristic feature of HiPS is that every level of the tree corresponds to a specific length and time scale, which is based on turbulence inertial range scaling. The state variables only reside at the base of the tree and are understood as fluid parcels. The effects of turbulent advection are represented by stochastic swaps of sub-trees at rates determined by prevailing turbulent time scales associated with the sub-trees. The mixing of adjacent fluid parcels is done either instantaneously or at rates consistent with the corresponding diffusion time scales. In this work, HiPS is detailed for the simulation of passive scalar mixing first. Preliminary results for the scalar power spectra, mean square displacement and scalar dissipation rate are shown and reveal a reasonable agreement with experimental findings. Furthermore, the integrated binary tree structure allows to satisfy a large number of criteria for a good mixing model. Considering the reduced order and computational efficiency, HiPS is an attractive candidate for modeling the mixing in transported PDF methods.}, 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 = {92nd Annual Meeting of the International Association of Applied Mathematics and Mechanics August 15-19, 2022 Aachen, Germany, Book of Abstracts}, journal = {92nd Annual Meeting of the International Association of Applied Mathematics and Mechanics August 15-19, 2022 Aachen, Germany, Book of Abstracts}, publisher = {RWTH Aachen University}, address = {Aachen}, language = {en} } @misc{SharmaMedinaMendezSchmidtetal., author = {Sharma, Dikshant and Medina M{\´e}ndez, Juan Ali and Schmidt, Heiko and Cremer, Tilman}, title = {Seasonal cold storage with borehole heat exchangers: an application study using numerical simulations}, series = {Tagungsband des Jahrestreffens der DECHEMA-Fachgruppen Computational Fluid Dynamics und W{\"a}rme- und Stoff{\"u}bertragung, 6.-8. M{\"a}rz 2023, Frankfurt am Main, Deutschland}, journal = {Tagungsband des Jahrestreffens der DECHEMA-Fachgruppen Computational Fluid Dynamics und W{\"a}rme- und Stoff{\"u}bertragung, 6.-8. M{\"a}rz 2023, Frankfurt am Main, Deutschland}, publisher = {DECHEMA e.V.}, address = {Frankfurt am Main}, pages = {18 -- 19}, language = {en} }