Article
Computer Science, Interdisciplinary Applications
F. Gand, M. Huet
Summary: This study evaluates a low-noise turbulence generation method to produce three-dimensional resolved turbulence at the exit of a jet nozzle. Combining the turbulence generation method with ZDES mode 3 produces satisfying levels of resolved turbulence. In comparison, ZDES mode 2 simulations display quick development of three-dimensional turbulence in the mixing layer. These results provide insights on the level of turbulent modeling needed for jet flow simulations.
COMPUTERS & FLUIDS
(2021)
Article
Mechanics
Xinxian Zhang, Tomoaki Watanabe, Koji Nagata
Summary: In this study, direct numerical simulations of temporally developing turbulent boundary layers were used to investigate the Reynolds number dependence of the turbulent/non-turbulent interface (TNTI) layer. The results revealed the mean thicknesses of the TNTI layer, turbulent sublayer, and viscous superlayer, as well as the characteristics of the irrotational boundary. It was found that the mean shear effects near the TNTI layer are not significant and that the turbulence under the TNTI layer tends to be isotropic at high Reynolds numbers.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Michele Cogo, Francesco Salvadore, Francesco Picano, Matteo Bernardini
Summary: The structure of high-speed zero-pressure-gradient turbulent boundary layers was studied using direct numerical simulation of the Navier-Stokes equations up to high Reynolds numbers, revealing the consequences in supersonic and hypersonic conditions. Instantaneous fields showed elongated strips of uniform velocity and temperature with clear associations between different streaks.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Masoud Asadi, Md Kamruzzaman, R. Jason Hearst
Summary: The impact of inlet turbulence on the structure of turbulent channel flow was investigated using particle image velocimetry. The results showed that the friction velocity remained constant with varying turbulence intensities and the log region remained intact. However, the increased turbulence intensity resulted in increased discontinuity and new core states with different characteristic velocities. Furthermore, the core tended to move closer to the wall and the core thickness increased with increased inlet turbulence intensity.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Physics, Fluids & Plasmas
Masoud Asadi, Md. Kamruzzaman, R. Jason Hearst
Summary: The study found that localized injection and inlet turbulence have significant impacts on turbulent channel flow, with localized injection forming an affected layer (AL) and inlet turbulence facilitating the transport of the AL away from the wall to the outer layer. Additionally, inlet turbulence amplifies streamwise fluctuations and influences the Reynolds shear stress contributions, while localized injection affects the distribution of fluctuations in near-wall regions.
PHYSICAL REVIEW FLUIDS
(2022)
Article
Mechanics
Akanksha Baranwal, Diego A. Donzis, Rodney D. W. Bowersox
Summary: This study investigates the effects of compressibility on the near-wall asymptotic behavior of turbulent fluxes using a large direct numerical simulation (DNS) database, finding that the behavior of compressible turbulent flow near walls differs from incompressible flow even when mean density variations are considered. As Mach number increases, turbulent fluxes containing wall-normal components exhibit a decrease in slope due to increased dilatation effects, with Ity approaching its high Mach number asymptote at lower Mach numbers than other fluxes.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
J. C. Klewicki
Summary: High resolution direct numerical simulation data are used to investigate the similarity solutions for mean velocity and Reynolds shear stress in turbulent channel flow. The analysis yields an invariant form of the mean momentum equation valid over a significant portion of the flow domain. The results provide insights into the development of wall-flow models and support conjectures regarding the behavior of similarity parameters at large Reynolds numbers.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Jonathan Neuhauser, Kay Schaefer, Davide Gatti, Bettina Frohnapfel
Summary: Heterogeneous roughness in the form of streamwise aligned strips can generate large scale secondary motions under turbulent flow conditions. We propose a simple roughness model that can capture the features of turbulent secondary flow without impacting the laminar base flow. The model shows good agreement with experimental data in terms of the secondary flow topology.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Jie Yao, Fazle Hussain
Summary: Compressible turbulent plane Couette flows with high Reynolds and Mach numbers were studied through direct numerical simulation. Various turbulence statistics were compared with incompressible flows. The skin friction coefficient decreases with Reynolds number but weakly depends on Mach number. The thermodynamic properties show significant variations with Mach number. Proper scaling transformations collapse the mean velocity profiles for compressible and incompressible cases well. Semilocal units yield a better collapse for Reynolds stress profiles compared to wall units. The length scale of near-wall coherent structures and the strength of the superstructures increase with Reynolds number. The streamwise coherence of the superstructures degrades with increasing Mach number.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
C. Chen, L. He
Summary: Recent findings on wall-bounded turbulence have led to the development of a new modelling method to capture the influence of large-scale coherent structures and scale-interaction on near-wall turbulence. This paper presents a two-scale approach to simulate this influence and validates its effectiveness.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Meteorology & Atmospheric Sciences
Joshua B. Wadler, David. S. Nolan, Jun A. Zhang, Lynn K. Shay, Joseph B. Olson, Joseph J. Cione
Summary: This study estimates the distribution of turbulent kinetic energy (TKE) and its budget terms in simulated tropical cyclones. The results show that TKE is maximized at low levels and inward of the region of maximum wind speed. The study has implications for improving hurricane simulations.
JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS
(2023)
Article
Mechanics
Y. X. Wang, K. -S. Choi, M. Gaster, C. Atkin, V. Borodulin, Y. Kachanov
Summary: The experimental investigation in a low-turbulence wind tunnel revealed that artificially initiated turbulent spots in a laminar boundary layer over a flat plate quickly developed into hairpin-like structures, increasing in width, length and height downstream. Only disturbances greater than a threshold value evolved into turbulent spots, while others decayed. The rate of development was also influenced by the duration of initial disturbances. Additionally, the behavior of turbulence generation within a turbulent spot was found to be similar to burst events in a turbulent boundary layer.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Andrea Andreolli, Davide Gatti, Ricardo Vinuesa, Ramis Oerlue, Philipp Schlatter
Summary: The presence of very-large-scale motions in wall-bounded turbulent flows is commonly associated with the superposition of large scales at the wall and the modulation of small-scale near-wall turbulence. This study challenges the current understanding by selectively suppressing either superposition or amplitude modulation and studying the remaining phenomenon. The results indicate that there is still a correlation between the amplitude of small scales near the wall and the large-scale signal in the outer flow even when near-wall large-scale motions are suppressed.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Mengze Wang, Tamer A. Zaki
Summary: Estimation of the initial state of turbulent channel flow from limited data is investigated using an adjoint-variational approach. The study demonstrates the robustness of the algorithm to observation noise and evaluates the impact of the spatiotemporal density of the data on estimation quality. Results show a resolution threshold for successful reconstruction and highlight the difficulty of reconstructing wall-detached motions from wall data.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Matthew A. Subrahmanyam, Brian J. Cantwell, Juan J. Alonso
Summary: This paper introduces a mixing length model for turbulent shear stress in pipe flow and provides a universal velocity profile. The velocity profile accurately approximates both experimental and simulated data in various flow conditions, making it significant for studying the statistical properties of flow.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Thermodynamics
Hao Xia, Wang Han, Xutao Wei, Meng Zhang, Jinhua Wang, Zuohua Huang, Christian Hasse
Summary: This study investigates the flashback phenomenon of hydrogen-enriched flames under different thermal boundary conditions. The results show that the characteristics of flashback are closely related to the boundary condition. Flashback can be led by either a large-scale swirling flame tongue (Mode I) or multiple small-scale flame bulges (Mode II), and the presence of these structures affects the speed of flashback. These findings have important implications for extending the flashback limit of hydrogen-enriched fuels.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
Shumeng Xie, Xinyi Chen, Hannes Boettler, Arne Scholtissek, Christian Hasse, Zheng Chen
Summary: Forced ignition is widely used in engines, but it is difficult to ignite mixtures with large Le. This study investigates the forced ignition of a fuel-rich H-2/air mixture with Le approximately 2.3 in a laminar counterflow. The counterflow greatly affects the ignition kernel development and minimum ignition energy (MIE) for Le approximately 2.3. Increasing the strain rate extinguishes the radial flame and increases the MIE. Surprisingly, moving the ignition position away from the stagnation point reduces the MIE and promotes ignition.
FLOW TURBULENCE AND COMBUSTION
(2023)
Article
Chemistry, Physical
Yujuan Luo, Federica Ferraro, Adrian Breicher, Hannes Boettler, Andreas Dreizler, Dirk Geyer, Christian Hasse, Arne Scholtissek
Summary: In this study, a flamelet model is used to describe lean CH4-H2-air laminar Bunsen flames with inert gas as a coflow, considering multiple complex physical phenomena. Transport equations for several species and enthalpy are solved, and species diffusivities are evaluated with a mixture-averaged diffusion model. The accuracy of the model is verified through comparison with detailed chemistry results and experimental measurements, showing good agreement and superiority of the four-dimensional manifold in the mixing layer.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Engineering, Mechanical
Hanna Reinhardt, Cetin Alanyalioglu, Andre Fischer, Claus Lahiri, Christian Hasse
Summary: This work presents an analysis of self-excited thermoacoustic instabilities using a hybrid method that combines incompressible computational fluid dynamics (CFD) and computational aeroacoustics (CAA) simulations. The hybrid method couples the acoustic and convective physical phenomena by using mean flow field quantities and the thermoacoustic energy source term as inputs. The suitability of this implementation is demonstrated through the analysis of a well-known self-excited instability in a Rijke tube, and the results are compared with a fully compressible reference solution.
JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME
(2023)
Article
Thermodynamics
Haris Lulic, Adrian Breicher, Arne Scholtissek, Pasquale Eduardo Lapenna, Andreas Dreizler, Francesco Creta, Christian Hasse, Dirk Geyer, Federica Ferraro
Summary: The objective of this study is to systematically characterize the polyhedral structures of premixed methane/hydrogen Bunsen flames through experimental and numerical investigations. It is observed that the cell sizes at the base of the polyhedral Bunsen flames decrease almost linearly with hydrogen addition and have a weak dependence on the equivalence ratio. The numerical results match the experimental findings, and the wavelength predicted by the linear stability analysis is comparable to the cell size obtained from the experiment.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
Matthias Steinhausen, Thorsten Zirwes, Federica Ferraro, Arne Scholtissek, Henning Bockhorn, Christian Hasse
Summary: This study investigates the thermochemical state of a stoichiometric methane-air flame during turbulent flame-wall interaction using detailed chemistry simulation. The simulation reveals both head-on quenching and side-wall quenching-like behavior, which greatly affects CO formation near the wall. The findings are used to evaluate a recently proposed flame vortex interaction mechanism, which shows similar flame behavior and thermochemical states observed in experiments. A novel chemistry manifold is presented that incorporates exhaust gas recirculation effects and improves prediction accuracy in flame-vortex interaction near-wall regions.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
Xu Wen, Ali Shamooni, Hendrik Nicolai, Oliver T. Stein, Andreas Kronenburg, Andreas M. Kempf, Christian Hasse
Summary: In this study, a carrier-phase direct numerical simulation (CP-DNS) is conducted to analyze a pulverized coal flame with flue gas recirculation (FGR). The study considers detailed gas phase kinetics and includes heavy hydrocarbon molecules. Two flamelet models are used to analyze the structure of the flame and evaluate their performance in predicting thermo-chemical quantities.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
Matthias Steinhausen, Federica Ferraro, Max Schneider, Florian Zentgraf, Max Greifenstein, Andreas Dreizler, Christian Hasse, Arne Scholtissek
Summary: This study investigates partially premixed laminar methane-air flames undergoing side-wall quenching using experimental and numerical methods. The results show that at high injection rates, a boundary layer of enriched mixture is formed at the wall, resulting in a reaction zone parallel to the wall. Numerical simulations reveal that injecting the wall inflow with a phosphor-based flame retardant (DMMP) can reduce the thermal load on the quenching wall and improve the stability of the flame. This study provides important insights into the combined effects of flame retardants and heat losses in near-wall flames.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Energy & Fuels
J. Janicka, P. Debiagi, A. Scholtissek, A. Dreizler, B. Epple, R. Pawellek, A. Maltsev, C. Hasse
Summary: This study assesses the possibility of converting an existing modern coal-fired power plant to operation with iron and its oxides, and finds that the main components can be reused with moderate modifications, but major modifications are needed for dealing with the larger amounts of solids produced during iron combustion. The net efficiencies of iron operation can be one to two percentage points better than coal operation, depending on operating conditions, which can significantly accelerate the introduction of this innovative technology.
Article
Computer Science, Interdisciplinary Applications
Emanuele Gallorini, Jerome Helie, Federico Piscaglia
Summary: A multi-objective continuous adjoint strategy has been implemented for topology optimization problems involving enhanced heat transfer and controlled mechanical power dissipation. The strategy is based on the superposition of boundary functions and is implemented in a finite volume, incompressible, steady flow solver with dynamic adaptive mesh refinement. The solver uses a porosity field to model the transition from fluid to solid and optimizes material distribution using the method of moving asymptotes. The implemented methodology is validated through numerical experiments on two- and three-dimensional test cases.
INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS
(2023)
Article
Physics, Fluids & Plasmas
Daniel Costero, Federico Piscaglia
Summary: This article discusses the insufficiency of introducing grid velocity in the transport terms of governing equations in achieving conservativeness in the computation of unsteady flow problems using the arbitrary Lagrangian-Eulerian (ALE) method, when there are changes in the dynamic mesh topology and mesh cell numbers. To achieve second-order time accuracy of the solution, an extension to second-order time differencing schemes (Implicit Euler and Crank-Nicolson) in the finite volume framework is proposed. Numerical experiments are presented to demonstrate the effectiveness of the method.
Article
Thermodynamics
Johannes Mich, Daniel Braig, Tobias Gustmann, Hristian Hasse, Arne Scholtissek
Summary: This study aims to explore the influence of polydispersity of iron particles on the reaction front speed. Three different models for iron particle oxidation were integrated into a laminar flame solver to simulate the reaction fronts. The results show that the different particle models lead to very different reaction front speeds due to the different ignition behavior predicted by the models. The study illustrates the complex relationship between characteristics of single particle ignition and combustion, polydispersity, and properties of reaction fronts.
COMBUSTION AND FLAME
(2023)
Article
Engineering, Aerospace
Federico Piscaglia, Federico Ghioldi
Summary: This paper introduces algorithmic advancements for accelerating simulations in OpenFOAM using GPUs. It discusses the use of the amgx4Foam library to connect the AmgX library from NVIDIA to OpenFOAM, as well as relocating the solution of finite-rate chemistry to GPUs. The performance of the developed algorithms is validated in aerodynamics calculations and supersonic combustion scenarios.
Article
Thermodynamics
Yan Wang, Shumeng Xie, Hannes Bottler, Yiqing Wang, Xinyi Chen, Arne Scholtissek, Christian Hasse, Zheng Chen
Summary: This study investigates how flow affects the ignition and transition process of a cool flame. The results show that the ignition energy determines the highest temperature and the strain rate influences the flame propagation and the transition from cool flame to hot flame.
COMBUSTION AND FLAME
(2024)
Article
Energy & Fuels
Robert Schmitz, Federica Ferraro, Mariano Sirignano, Christian Hasse
Summary: This study investigates the sooting propensity of different oxymethylene ethers (OMEs) and observes similar effects in reducing larger soot particles. The model predictions agree well with experimental results, and the importance of OME decomposition and formaldehyde formation for reducing soot precursor species is revealed.
Article
Computer Science, Interdisciplinary Applications
Jin Bao, Zhaoli Guo
Summary: At the equilibrium state of a two-phase fluid system, the chemical potential is constant and the velocity is zero. However, it is challenging to capture this equilibrium state accurately in numerical simulations, resulting in inconsistent thermodynamic interfacial properties and spurious velocities. Therefore, numerical schemes with well-balanced properties are preferred for simulating two-phase flows.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Brian C. Vermeire
Summary: This study presents a framework for implicit large eddy simulation (ILES) of incompressible flows by combining the entropically damped artificial compressibility (EDAC) method with the flux reconstruction (FR) approach. Experimental results demonstrate that the method is accurate and stable for low-order solutions, while higher-order solutions exhibit significantly higher accuracy and lower divergence error compared to reference direct numerical simulation.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Mijian Li, Rui Wang, Xinyu Guo, Xinyu Liu, Lianzhou Wang
Summary: In this study, the flow mechanisms around wall-mounted structures were investigated using Large Eddy Simulation (LES). The impact of inflow turbulence on the flow physics, dynamic response, and hydrodynamic performance was explored. The results revealed strong interference between velocity fluctuations and the wake past the cylinder, as well as significant convection effects in the far wake region.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Donatella Passiatore, Luca Sciacovelli, Paola Cinnella, Giuseppe Pascazio
Summary: A high-order shock-capturing central finite-difference scheme is evaluated for numerical simulations of hyper-sonic high-enthalpy flows out of thermochemical equilibrium. The scheme utilizes a tenth-order accurate central-difference approximation of inviscid fluxes, along with high-order artificial dissipation and shock-capturing terms. The proposed approach demonstrates accuracy and robustness for a variety of thermochemical non-equilibrium configurations.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Philipp Bahavar, Claus Wagner
Summary: Condensation is an important aspect in flow applications, and simulating the gas phase and tracking the deposition rates of condensate droplets can capture the effects of surface droplets on the flow while reducing computational costs.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Andras Szabo, Gyorgy Paal
Summary: This paper introduces an efficient calculation method, the parabolized stability equations (PSE), for solving stability equations. By calculating LU factorization once in each marching step, the time spent on solving linear systems of equations can be significantly reduced. Numerical experiments demonstrate the effectiveness of this method in reducing the solution time for linear equations, and its applicability to similar problems.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
A. Khalifa, M. Breuer
Summary: This study evaluates a recently developed data-driven model for collision-induced agglomerate breakup in high mass loading flows. The model uses artificial neural networks to predict the post-collision behavior of agglomerates, reducing computational costs compared to coupled CFD-DEM simulations.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Chunmei Du, Maojun Li
Summary: This paper considers the bilayer shallow water wave equations in one-dimensional space and presents an invariant domain preserving DG method to avoid Kelvin-Helmholtz instability.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Jean-Michel Tucny, Mihir Durve, Andrea Montessori, Sauro Succi
Summary: The prediction of non-equilibrium transport phenomena in disordered media is a challenging problem for conventional numerical methods. Physics-informed neural networks (PINNs) show potential for solving this inverse problem. In this study, PINNs were used to successfully predict the velocity field of rarefied gas flow, and AdamW was found to be the best optimizer.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Min Gao, Pascal Mossier, Claus-Dieter Munz
Summary: In recent decades, the arbitrary Lagrangian-Eulerian (ALE) approach has gained popularity in dealing with fluid flows with moving boundaries. This paper presents a novel algorithm that combines the ALE finite volume (FV) and ALE discontinuous Galerkin (DG) methods into a stable and efficient hybrid approach. The main challenge of this mixed ALE FV and ALE DG method is reducing the inconsistency between the two discretizations. The proposed algorithm is implemented into a loosely-coupled fluid-structure interaction (FSI) framework and is demonstrated through various benchmark test cases and complex scenarios.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Dawid Strzelczyk, Maciej Matyka
Summary: In this study, the numerical convergence of the Meshless Lattice Boltzmann Method (MLBM) is investigated through three benchmark tests. The results are compared to the standard Lattice Boltzmann Method (LBM) and the analytical solution of the Navier-Stokes equation. It is found that MLBM outperforms LBM in terms of error value for the same number of nodes discretizing the domain.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Kanishka Bhattacharya, Tapan Jana, Amit Shaw, L. S. Ramachandra, Vishal Mehra
Summary: In this work, an adaptive algorithm is developed to address the issue of tensile instability in Smoothed Particle Hydrodynamics (SPH) by adjusting the shape of the kernel function to satisfy stability conditions. The effectiveness of the algorithm is demonstrated through dispersion analysis and fluid dynamics simulations.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Luis Laguarda, Stefan Hickel
Summary: We propose several enhancements to improve the accuracy and performance of the digital filter turbulent inflow generation technique, such as introducing a more realistic correlation function and varying target length scales. Additionally, we suggest generating inflow data in parallel at a prescribed time interval to improve computational performance. Based on the results of large-eddy simulations, these enhancements have shown to be beneficial. Suppressing streamwise velocity fluctuations at the inflow leads to the fastest relaxation of pressure fluctuations. However, this approach increases the adaptation length, which can be shortened by artificially increasing the wall-normal Reynolds stresses.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Constantin Zenz, Michele Buttazzoni, Tobias Florian, Katherine Elizabeth Crespo Armijos, Rodrigo Gomez Vazquez, Gerhard Liedl, Andreas Otto
Summary: A new model for compressible multiphase flows involving sharp interfaces and phase change is presented, with a focus on the treatment of compressibility and phase change in the multiphase fluid flow model. The model's accuracy and suitability are demonstrated through comparisons with experimental observations.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Joseph O'Connor, Sylvain Laizet, Andrew Wynn, Wouter Edeling, Peter V. Coveney
Summary: This article aims to apply uncertainty quantification and sensitivity analysis to the direct numerical simulation (DNS) of low Reynolds number wall-bounded turbulent channel flow. By using a highly scalable DNS framework and UQ techniques, the study evaluates the influence of different numerical parameters on the simulation results without explicitly modifying the code. The findings provide guidance for numerical simulations of wall-bounded turbulent flows.
COMPUTERS & FLUIDS
(2024)