Article
Energy & Fuels
C. Segatori, A. Piano, B. Peiretti Paradisi, F. Millo, A. Bianco
Summary: Computational Fluid Dynamics (CFD) with Large Eddy Simulation (LES) turbulence model is a valuable tool for investigating complex problems. However, high Reynolds number problems often lead to the use of simplified and less accurate approaches due to the huge computational cost. In this study, a runtime saving methodology was developed to increase the number of independent samples for ensemble average, resulting in a significant reduction in computational cost without sacrificing accuracy.
Article
Thermodynamics
Sergio Croquer, Olivier Lamberts, Sebastien Poncet, Stephane Moreau, Yann Bartosiewicz
Summary: This study investigates the flow topology in the mixing chamber of a supersonic ejector using Large Eddy Simulation (LES). The results show that the mixing layer transitions from laminar to turbulent and vortices are identified in the first quarter of the mixing chamber. The study also reveals the occurrence of shock train towards the end of the mixing chamber, enhancing mixing.
APPLIED THERMAL ENGINEERING
(2022)
Article
Thermodynamics
S. Wadekar, A. Yamaguchi, M. Oevermann
Summary: The study analyzed the development of gasoline spray at ultra-high injection pressures using Large-Eddy simulation (LES). Results indicated that at high injection pressures, the mean droplet sizes of the spray were significantly reduced with very high velocities, while the spray-induced large-scale eddies and air entrainment rate increased with higher injection pressures.
FLOW TURBULENCE AND COMBUSTION
(2021)
Article
Computer Science, Interdisciplinary Applications
A. C. W. Creech, A. Jackson
Summary: This paper introduces a hybrid approach for explicitly-filtered Large Eddy Simulation using a Discontinous Galerkin discretisation for velocity, which incorporates information from a Continuous Galerkin version of the velocity field to improve computational performance while maintaining stability and accuracy.
COMPUTER PHYSICS COMMUNICATIONS
(2021)
Article
Meteorology & Atmospheric Sciences
Yu Cheng, Marco G. Giometto, Pit Kauffmann, Ling Lin, Chen Cao, Cody Zupnick, Harold Li, Qi Li, Yu Huang, Ryan Abernathey, Pierre Gentine
Summary: In large-eddy simulations, subgrid-scale processes are parameterized as a function of filtered grid-scale variables. This paper applies supervised deep neural networks (DNNs) to learn subgrid stresses and achieves higher correlation compared to traditional models, with applicability to different resolutions and stability conditions.
JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS
(2022)
Article
Mechanics
Daniel Fredrich, Erik Weiand, Andrea Giusti
Summary: This study proposes the use of electrostatic fields to control the position of electrically charged fuel droplets, enhancing pre-evaporation of liquid sprays in confined spaces. Numerical simulations and a deterministic model were used to investigate the feasibility and effects of this approach. Results show that external electrostatic fields can change droplet trajectory and potentially stabilize the spray position, improving evaporation rate and mixing quality.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2023)
Article
Construction & Building Technology
Jun Wang, Li Wang, William(Wei) Zhang
Summary: The study focuses on turbulence energy spectrum of fluctuating inflow velocity in LES, proposing a projection algorithm to modify the previous spectrum method. The validated procedure showed better performance and revealed specific oscillation patterns in flow change rate around openings in building natural ventilation design.
BUILDING AND ENVIRONMENT
(2021)
Article
Engineering, Aerospace
Mohammad Khalid Hossen, Asokan Mulayath Variyath, Jahrul M. Alam
Summary: This study investigates the statistical characteristics of vortex stretching in Large Eddy Simulation (LES) and finds that the stretching rate provides the necessary energy dissipation rate for modeling subgrid-scale turbulence. By comparing the interaction of subgrid stresses with filtered quantities, it is revealed that the stretching mechanism extracts energy from large-scale motion and transfers it to small-scale stretched vortices.
Article
Mechanics
Xander M. de Wit, Adrian van Kan, Alexandros Alexakis
Summary: In this study, direct numerical simulations of thin-layer flow were used to investigate whether the bistable range survives as the domain size and turbulence intensity are increased. The research found that the bistable range grows as the box size and/or Reynolds number Re are increased.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Thermodynamics
Marius Kurz, Philipp Offenhaeuser, Andrea Beck
Summary: In recent years, supervised learning has become the state-of-the-art approach for data-driven turbulence modeling. However, this approach is not feasible for implicitly filtered large eddy simulation (LES) due to the unknown filter form. To address this issue, reinforcement learning is applied to directly interact with the LES environment and incorporate the implicit LES filter into the training process. The trained models demonstrate long-term stability, outperform analytical models, and generalize well to different resolutions and discretizations.
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2023)
Article
Mechanics
Andreas Freund, Antonino Ferrante
Summary: The proposed MANN LES method effectively simulates turbulent flows laden with droplets by utilizing artificial neural networks to predict the subgrid-scale (SGS) closure terms at the interface. This approach demonstrates good reproduction performance under different Weber numbers for droplets.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2021)
Article
Engineering, Multidisciplinary
M. Salinas-Vazquez, J. Ramirez-Cruz, W. Vicente, E. Martinez-Espinosa, H. M. Avina-Jimenezez, C. Lagarza-Cortes
Summary: The study used Large Eddy Simulation to numerically simulate the flow around a circular tube bundle, showing good agreement between simulated and experimental data, and identifying turbulent structures that can improve heat transfer.
APPLIED MATHEMATICAL MODELLING
(2021)
Article
Mathematics, Applied
Di Sun, Feng Qu, Junqiang Bai
Summary: In this study, an Implicit Large Eddy Simulation (ILES) method based on all-speed schemes in a framework of the finite volume method is analyzed for the simulation of complex flow structures in both high and low Mach numbers regimes. The method shows good accuracy in capturing compressible phenomena and small turbulent structures. The application of the method to cylinder flow and transonic cavity flow yields results in agreement with previous studies, indicating its promising potential for complex engineering flow problems.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2022)
Article
Engineering, Mechanical
Noor Muhammad, Maha M. A. Lashin, Soliman Alkhatib
Summary: Turbulent flow is characterized by unpredictable fluctuations in pressure and flow velocity. Turbulence modeling aims to predict time-averaged velocity, turbulence kinetic energy, and pressure. This study analyzes turbulence kinetic energy using an LES model and examines the pressure, fluctuations, and mean velocity caused by turbulence.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART E-JOURNAL OF PROCESS MECHANICAL ENGINEERING
(2022)
Article
Meteorology & Atmospheric Sciences
Ali Khosronejad, Ajay B. B. Limaye, Zexia Zhang, Seokkoo Kang, Xiaolei Yang, Fotis Sotiropoulos
Summary: The interaction between flow, sediment transport, and bed topography plays a crucial role in the formation of bedforms and channel migration in meandering rivers. Predicting these interactions is vital for river engineering and geoscience research. Researchers conducted simulations to study the morphodynamics and bed deformation in 42 meandering rivers with different planform shapes. The simulations revealed the formation of scour and deposition patterns near the outer and inner banks and the variation of point bars and scour regions around the meander bends.
JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS
(2023)
Article
Thermodynamics
Navid Freidoonimehr, Azadeh Jafari, Maziar Arjomandi
Summary: In this study, a high-fidelity flow visualisation technique is used to investigate the resemblance between a turbulent boundary layer generated by different tripping devices in a lab environment and a naturally developed canonical turbulent boundary layer. The study finds that the blockage created by trips is the main factor affecting the turbulence statistics at a certain downstream distance.
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2024)
Article
Thermodynamics
Yuning Wang, Alberto Solera-Rico, Carlos Sanmiguel Vila, Ricardo Vinuesa
Summary: This study proposes a method that combines 6-VAEs for modal decomposition and transformer neural networks for temporal-dynamics prediction in the latent space to develop reduced-order models (ROMs) for turbulent flows. The method achieves high reconstruction accuracy and accurate prediction of temporal dynamics.
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2024)
Article
Thermodynamics
L. Laguarda, S. Hickel, F. F. J. Schrijer, B. W. van Oudheusden
Summary: Wall-resolved large-eddy simulations were used to investigate the Reynolds number effects in supersonic turbulent boundary layers at Mach 2.0. The study covered a wide range of friction Reynolds numbers and identified trends in various statistics and scaling laws. The size and topology of turbulent structures in the boundary layer were examined, with a focus on the outer-layer motions at high Reynolds numbers. The study also assessed the influence of outer-layer structures on near-wall turbulence and the sensitivity of uniform momentum regions to compressibility.
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2024)
Article
Thermodynamics
A. Doehring, T. Kaller, S. J. Schmidt, N. A. Adams
Summary: In this study, well-resolved large-eddy simulations were used to investigate turbulent duct flows with a square cross section. The influence of a modified wall shear stress on the secondary flow was analyzed by artificially modifying the wall shear stress at one of the four walls. The results showed that the modification led to an asymmetrical distribution of the secondary flow source terms, affecting the momentum distribution. Furthermore, the anisotropy of the Reynolds stress tensor, which induces the secondary flow vortices, was significantly affected by the wall shear stress modulation.
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2024)
