Article
Mechanics
Han Qi, Xinliang Li, Changping Yu
Summary: This paper introduces a new one-equation eddy-viscosity model based on SGS helicity for LES of turbulent flows. The model is tested and validated in homogeneous and isotropic helical turbulence simulations, showing improved accuracy in predicting energy and helicity spectra. The model also accurately predicts mean velocity, turbulent stress, and viscous shear stress in channel flow LES, providing more flow structures compared to traditional SGS models.
Article
Mechanics
Wei-wen Zhao, Fu-chang Zhou, Guo-qing Fan, De-cheng Wan
Summary: This paper numerically simulates turbulent channel flow at Re-& tau; = 1000 using the wall-modeled large-eddy simulation (WMLES) method in conjunction with four different subgrid-scale (SGS) models. The effects of SGS models on predicting turbulent channel flow with WMLES are evaluated by comparing mean velocity profiles, velocity fluctuations, and energy spectra.
JOURNAL OF HYDRODYNAMICS
(2023)
Article
Engineering, Chemical
Yang Liu, Lixing Zhou
Summary: This paper investigates the effects of subgrid scale (SGS) gas flow on particle dynamics in particle-laden swirling turbulent flow. A novel particle SGS kinetic turbulent energy-granular temperature (SGS-kp-Theta p) model is proposed to model this effect on particle motions and dispersions. The results show good agreement with experimental data and simulations, indicating the accuracy of the proposed model.
Article
Multidisciplinary Sciences
Ryley McConkey, Eugene Yee, Fue-Sang Lien
Summary: The surge in machine learning augmented turbulence modelling offers a promising approach to address RANS models' limitations. This work introduces the development of an open-source dataset curated for immediate use in machine learning augmented corrective turbulence closure modelling, reducing effort required for training and testing new RANS models.
Article
Thermodynamics
Fatiha Nmira, Jean-Louis Consalvi
Summary: The present study aims to quantify individual contributions to turbulence-radiation interaction in large methanol pool fires and provide guidance for the development of simplified models. The study finds that temperature self-correlation and absorption coefficient-temperature cross correlation are the main contributors to both resolved-scale and subgrid-scale emission TRI. The contribution of subgrid-scale absorption coefficient self-correlation becomes negligible as the pool size increases.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Mechanics
Ken-ichi Abe
Summary: This study investigates the effect of filter width definition on the prediction accuracy of a subgrid scale (SGS) model in Large Eddy Simulation (LES). It is found that using the cube root of grid-cell volume as the filter width may not always be appropriate, and the influence of a grid width in one direction much smaller than in other directions should be excluded when determining the filter width for proper evaluation of an SGS model.
Article
Mechanics
Yuan Ding, Bi-yu Pang, Bo-wen Yan, Yi-qian Wang, Yu-xuan Chen, Yue-hong Qian
Summary: The concept of vortex is crucial in understanding and modeling turbulence. This study develops a new subgrid model based on the Liutex vector to identify vortices. The new model performs well in decaying homogeneous isotropic turbulence and turbulent channel flow. Future directions include improving the Liutex based model and applying it in various turbulent flows.
JOURNAL OF HYDRODYNAMICS
(2022)
Review
Mechanics
Robert D. Moser, Sigfried W. Haering, Gopal R. Yalla
Summary: This review focuses on the a priori statistical characteristics of large eddy simulation (LES) models, highlighting the importance of other subgrid statistical characteristics in complex turbulent flows and the consistency of these characteristics in models. The assessment of known statistical characteristics of subgrid models is aimed at aiding the ongoing development of LES models.
ANNUAL REVIEW OF FLUID MECHANICS, VOL 53
(2021)
Article
Thermodynamics
Jian Teng, Zelong Yuan, Jianchun Wang
Summary: Based on the framework of deconvolutional artificial neural network (DANN), this study extends the DANN approach to model subgrid-scale (SGS) terms in chemically reacting compressible turbulent flow. The DANN method outperforms traditional methods in terms of modeling performance and can predict flow variables accurately using limited training samples.
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2022)
Article
Mechanics
Aurelien Vadrot, Xiang I. A. Yang, H. Jane Bae, Mahdi Abkar
Summary: This paper focuses on the use of reinforcement learning (RL) for near-wall turbulence modeling. A new RL wall model (WM) called VYBA23 is developed, which uses agents dispersed in the flow near the wall. The model is trained on a single Reynolds number and does not rely on high-fidelity data. The results show potential for developing RLWMs that can recover physical laws and for extending this type of ML models to more complex flows in the future.
Article
Mechanics
Junhyuk Kim, Hyojin Kim, Jiyeon Kim, Changhoon Lee
Summary: The development of a reliable subgrid-scale (SGS) model for large-eddy simulation (LES) is essential for scientific and engineering applications. This study proposes a physics-constrained deep reinforcement learning (DRL) framework for developing a deep neural network-based SGS model for LES of turbulent channel flow. The DRL models are trained based on the local gradient of the filtered velocities, and experiments show that they can produce SGS models consistent with the filtered DNS in various environments.
Article
Computer Science, Interdisciplinary Applications
Felipe O. Basso, Admilson T. Franco, Diogo B. Fitz
Summary: This paper investigates the turbulent pipe flow of viscoplastic fluids using large-eddy simulation (LES) and the OpenFOAM package. The performance of different models for non Newtonian fluids is evaluated, and the numerical results are compared with direct numerical simulation (DNS) results and experimental data for turbulent pipe flow of a Newtonian fluid to validate the numerical method.
COMPUTERS & FLUIDS
(2022)
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
Thermodynamics
Ilyas Yilmaz
Summary: This paper develops a SGS model for LES of turbulent flows, taking into account buoyancy and modifying the turbulent generation term in SGS viscosity. The results show that the new model performs better than existing models in predicting turbulent diagnostics, especially in turbulent thermal convection.
INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW
(2021)
Article
Engineering, Environmental
Yang Liu, Lixing Zhou
Summary: The flow structures of non-swirling and swirling particle-laden turbulence are modeled using large eddy simulation. The interaction mechanism between gas and particles, particles and gas, and particle-particle collisions are revealed through a new proposed subgrid scale particle kinetic energy-granular temperature model. Numerical predictions of particle vortices, coherent structures, and dynamics are in good agreement with experimental measurements. The study highlights the differences in particle transport characteristics and turbulent fluctuations between non-swirling and swirling flows.
PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
(2022)
Article
Physics, Fluids & Plasmas
C. Sanmiguel Vila, R. Vinuesa, S. Discetti, A. Ianiro, P. Schlatter, R. Orlu
PHYSICAL REVIEW FLUIDS
(2020)
Article
Thermodynamics
Leandra Abreu, Andre V. G. Cavalieri, Philipp Schlatter, Ricardo Vinuesa, Dan S. Henningson
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2020)
Article
Thermodynamics
M. Samie, W. J. Baars, A. Rouhi, P. Schlatter, R. Orlu, I Marusic, N. Hutchins
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2020)
Article
Thermodynamics
Valerio Lupi, Jacopo Canton, Philipp Schlatter
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2020)
Editorial Material
Physics, Fluids & Plasmas
R. Orlu, P. Schlatter
PHYSICAL REVIEW FLUIDS
(2020)
Article
Physics, Fluids & Plasmas
Yitong Fan, Weipeng Li, Marco Atzori, Ramon Pozuelo, Philipp Schlatter, Ricardo Vinuesa
PHYSICAL REVIEW FLUIDS
(2020)
Article
Thermodynamics
Ali Mohammad Ranjbar, Zeinab Pouransari, Majid Siavashi
Summary: This study investigated the turbulent forced convection heat transfer of air in the presence of porous pin fins for cooling thermal parts of devices. Five fin structures, two different fin arrangements, and three various Darcy numbers were examined to analyze the effects of these parameters on the heat sink performance. It was concluded that the decreasing-aligned pin fin configuration with the highest Darcy number provided the best performance among the studied cases.
APPLIED THERMAL ENGINEERING
(2021)
Article
Chemistry, Multidisciplinary
Hasti Makhdoum, Zeinab Pouransari
Summary: This study focuses on analyzing the oil and natural gas reserves of Iran, which play a crucial role in the global energy market. The Hubbert peak theory is used to analyze and predict the production rates of these nonrenewable reserves. The study also compares Iran's reserves with other key countries and examines the impact of local consumption and international sanctions on Iran's production. In addition, global energy policies and the future outlook for Iran's oil and natural gas production are discussed.
Article
Thermodynamics
Mahyar Seyd Eshaghi, Mohammad Ameri, Amin Rasam, Mokhtar Bidi
Summary: In this study, numerical simulations are employed to analyze the hydrodynamic and thermal entrance regions of turbulent flow in a circular tube with a tight-fit twisted tape insert and prescribed constant wall temperature. Ethylene glycol, water, and Therminol-LT are considered, with inlet velocities ranging from 0.4 to 1 m/s and three common pitch ratios of 5, 8, and 10. The simulations utilize the RANS equations with the Boussinesq hypothesis and the SST-K-Omega turbulence model. Mean non-dimensional velocity and temperature profiles are assessed to confirm the flow's full development. Distinguishing features of the developing and fully-developed regions are compared using velocity and temperature profiles, contours, and flow streamlines. This analysis provides a novel guideline for assessing flow development in pipe flows with twisted-tape inserts. Correlations for dimensionless hydrodynamic and thermal entrance lengths, as well as Nu and Fanning friction factor, are proposed for the first time, allowing for the estimation of these quantities under a wide range of operating conditions.
THERMAL SCIENCE AND ENGINEERING PROGRESS
(2023)
Article
Mechanics
Zeinab Pouransari, Amin Rasam
Summary: An extension of the explicit algebraic subgrid-scale (SGS) stress model (EASSM) is proposed to account for the non-local equilibrium between the production, P, and viscous dissipation, e, of the SGS turbulent kinetic energy. The new derivation extracts a cubic algebraic equation for P/e from the modeled transport equation for the SGS stress anisotropy, improving the EASSM predictions with less computational costs. The performance assessment shows that the enhanced EASSM formulation reduces resolution dependence and improves predictions at low resolutions, affecting various turbulence statistics of interest.
Article
Mechanics
Zeinab Pouransari
Summary: This study investigates the statistical properties of small-scale scalar fluctuations in wall-bounded turbulent flows. The presence of a magnetic field leads to statistical anisotropy, even at small-scale gradient fields. Furthermore, an increase in scalar dissipation rates decreases the mixing timescale, potentially enhancing overall mixing.
Article
Energy & Fuels
Zeinab Pouransari, Mohadese Behzad
Summary: A numerical simulation study investigates the performance of a hybrid wind turbine design combining Darrieus and Savonius turbines. The study suggests three hybrid turbine designs, T-II, T-III, and T-IV, with the same Darrieus turbine. Results show that the power coefficient, C-p, varies differently with the tip speed ratio, TSR, for the hybrid turbines compared to the Darrieus turbine alone. The proposed T-IV turbine exhibits higher C-p than the base T-I turbine at the highest TSR.
Article
Physics, Multidisciplinary
Miguel Beneitez, Yohann Duguet, Philipp Schlatter, Dan S. Henningson
PHYSICAL REVIEW RESEARCH
(2020)
Article
Mechanics
Amin Rasam, Zeinab Pouransari