Article
Mechanics
Carlo Cossu
Summary: In this study, the genesis of large-scale coherent rolls in turbulent wall-bounded flows was investigated through linear stability analysis, revealing the importance of modeling turbulent Reynolds stresses for consistent predictions. The onset of large-scale convection was found to be associated with a critical friction Richardson number.
JOURNAL OF FLUID MECHANICS
(2022)
Review
Thermodynamics
Peyman Mayeli, Gregory J. Sheard
Summary: This review paper discusses various methods for numerical simulation of laminar natural convection, including Boussinesq and nonBoussinesq approximations, classified into compressible and incompressible categories.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2021)
Article
Mechanics
Enhui Chen, Feng Xu
Summary: Transient thermocapillary convection flows driven by heated lateral walls in a rectangular cavity under zero-gravity conditions were investigated using scaling analysis and numerical simulation. Various flow regimes were identified based on Marangoni and Prandtl numbers, with corresponding scaling laws for thickness and velocity obtained. Two-dimensional numerical simulations confirmed good agreement with the scaling predictions.
Article
Mechanics
M. Taha, S. Zhao, A. Lamorlette, J. L. Consalvi, P. Boivin
Summary: The pressure-based hybrid lattice-Boltzmann method proposed by Farag et al. was evaluated for simulating buoyancy driven flows. Validation studies on different cases and comparison with experimental results showed good overall agreement in terms of mean and fluctuation quantities, as well as global entrainment.
Article
Mechanics
Hamid Emami-Meybodi, Fengyuan Zhang
Summary: This study focuses on the buoyancy-driven stability analysis in a three-dimensional inclined porous medium with a capillary transition zone. The results of linear stability analysis and numerical solutions show that the inclination angle plays a crucial role in the stability of the problem.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Thermodynamics
Alexandre Fabregat, Jordi Pallares
Summary: Airborne particle transport and deposition on solid surfaces are crucial in aerosol deposition, infectious diseases transmission, and surface soiling. Fluids disperse particles through various forces, influenced by density ratio and particle size. The boundary layers and these parameters control the localized wall deposition rate.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
Chan-Sol Ahn, Boo-Hyoung Bang, Chanwoo Park, Doo-Young Kim, Alexander L. Yarin, Sam S. Yoon
Summary: This study presents analytical solutions and experimental results on smoke dynamics in vertical shafts, revealing the characteristics of heat-induced convection flow under different heat flux conditions, providing important insights for fire and building safety engineering.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2021)
Article
Mechanics
A. Mizev, E. A. Mosheva, D. A. Bratsun
Summary: In the experimental study, buoyancy-driven instabilities triggered by neutralization reactions were investigated, and a dimensionless parameter called reaction-induced buoyancy number was introduced to classify experimental observations and predict the development of two global scenarios based on the value of this parameter.
One scenario is mainly controlled by diffusion, resulting in weak convective motion, while the other leads to vigorous convection in the upper layer, causing the reaction front to move downwards quickly. A new parameter was shown to plot stability maps for predicting reaction-diffusion-convection processes in similar systems before experiments.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Physics, Fluids & Plasmas
Chao-Ben Zhao, Yi-Zhao Zhang, Bo-Fu Wang, Jian-Zhao Wu, Kai Leong Chong, Quan Zhou
Summary: We numerically studied the turbulent Rayleigh-Benard convection with spatial temperature modulation. It was found that small wave number modulation can enhance the global heat transfer, while large wave number modulation shows similar heat transfer characteristics as standard convection. Based on the comparison between the boundary layer thickness and modulation length scales, three modulation regimes were identified.
Article
Nuclear Science & Technology
Chunhui Dong, Guoqing Lu, Ronghua Chen, Kui Zhang, Changliang Liu, Wenxi Tian, Suizheng Qiu, G. H. Su
Summary: In this study, experiments were conducted on the turbulent natural convection of air for PAS, investigating the heat transfer and flow rate induced by buoyancy. The results showed that the heat transfer coefficient increases with decreasing inclination angle when the heated wall is inclined upward, while the pressure loss decreases due to the decrease in velocity gradient. Heat transfer and flow rate correlations considering the influence of inclination angle were proposed based on the experimental data, which can be used to predict the heat transfer and flow rate for PAS. Additionally, a criterion for classifying mixed and natural convection was derived. These research findings have practical applications in enhancing the thermal-hydraulics analysis of PAS to improve nuclear power plant safety.
ANNALS OF NUCLEAR ENERGY
(2023)
Article
Thermodynamics
Nikolay A. Vinnichenko, Yulia Yu. Plaksina, Alexey V. Pushtaev, Alexander V. Uvarov
Summary: A new hybrid simulation technique is proposed for natural convection flows, which combines experimental measurements with numerical integration. The technique can obtain velocity and pressure fields without extra measurements by using experimental temperature distributions to determine the buoyancy term. It is demonstrated for Background Oriented Schlieren measurements and shows good agreement with numerical simulations, but may lead to underprediction of velocity and pressure disturbances due to limited measurement region or underestimation of peak temperature.
APPLIED THERMAL ENGINEERING
(2022)
Article
Mechanics
Xuan Zhang, Robert E. Ecke, Olga Shishkina
Summary: In rapidly rotating turbulent Rayleigh-Benard convection with a small Prandtl number fluid in slender cylindrical containers, a boundary zonal flow (BZF) is found to develop near the sidewall, carrying a disproportionate amount of heat transport for Pr < 1 but decreasing abruptly for larger Pr. The BZF is robust and appears in containers of different aspect ratios and over a broad range of Pr and Ra values.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Thermodynamics
Kenneth Chinembiri, Shuisheng He, Jiankang Li
Summary: The study investigated highly turbulent natural circulation in an enclosed tall rod bundle using Large Eddy Simulation (LES). The flow, turbulence, and thermal characteristics of the system showed distinct features strongly influenced by the vertically developing buoyancy-driven boundary layer on the containment surface. The top region exhibited stagnant flow with thermal stratification, while the middle region showed split flow into outer and central zones, resembling mixed convection in a heated pipe/channel flow.
APPLIED THERMAL ENGINEERING
(2021)
Article
Computer Science, Interdisciplinary Applications
D. Dupuy, N. Odier, C. Lapeyre
Summary: This paper examines a data-driven approach for modeling the wall shear stress in large-eddy simulation of high Reynolds number wall-bounded turbulent flows. The model is a multilayer perceptron based on flow information near the wall, and it is able to extrapolate to unseen flow conditions. The model is verified using filtered numerical data and implemented in wall-modeled large-eddy simulations, showing its ability to discriminate developed wall turbulence and separated regions.
JOURNAL OF COMPUTATIONAL PHYSICS
(2023)
Article
Thermodynamics
Junjie Liu, Xieeryazidan Aday, Guanlin Zhou, Zhenghe Ma
Summary: A new electrochemical machining model was established to study Marangoni and buoyancy-driven convection, with numerical simulations and experiments investigating the mechanisms of convection formation. Results showed that convection cells transitioned to an annular structure as processing voltage increased, forming both Marangoni and buoyancy convection in the processing region.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
P. Chorin, F. Moreau, D. Saury
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2020)
Article
Engineering, Multidisciplinary
Elissa El Rassy, Yann Billaud, Didier Saury
MEASUREMENT SCIENCE AND TECHNOLOGY
(2020)
Article
Thermodynamics
Yang Liu, Yann Billaud, Didier Saury, Denis Lemonnier
NUMERICAL HEAT TRANSFER PART A-APPLICATIONS
(2020)
Article
Thermodynamics
P. Chorin, F. Moreau, Y. Billaud, D. Lemonnier, D. Saury
NUMERICAL HEAT TRANSFER PART A-APPLICATIONS
(2020)
Article
Thermodynamics
Elissa El Rassy, Yann Billaud, Didier Saury
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2020)
Article
Engineering, Multidisciplinary
Elissa El Rassy, Yann Billaud, Didier Saury
Summary: This work presents a method for simultaneous identification of thermal diffusivities of coatings or thin film materials, also implying the identification of substrate thermal properties. The method is based on resolving an inverse problem using a stochastic optimization algorithm, requiring a non-intrusive test involving infrared camera and CO2 laser excitation. Experimental evaluation shows feasibility, robustness, and accuracy of the method in estimating thermal diffusivity of coatings used in thermographic phosphor thermometry.
APPLIED MATHEMATICAL MODELLING
(2021)
Article
Thermodynamics
Paul Chorin, Florian Moreau, Didier Saury
Summary: In this numerical study, natural convection flow in a differentially heated cavity was examined, with a focus on the impact of a localized thermal disturbance on heat transfer. Results indicate that the optimal disturbance location is at the top of the hot wall, and maximal heat transfers are achieved at specific low frequencies. The disturbance also leads to the emergence of traveling waves and unsteady behavior in the flow.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2021)
Article
Thermodynamics
Manuel Girault, Yang Liu, Yann Billaud, Adel M. Benselama, Didier Saury, Denis Lemonnier
Summary: This study focuses on the characterization of thermophysical properties of semi-transparent gray media using P1 approximation for radiative transfers. It develops, constructs, and validates conducto-radiative linear reduced order models (ROMs) explicitly parametrized by thermal conductivity and effective absorption coefficient. By linearizing the radiative contribution in the ROM formulation and using the Modal Identification Method (MIM), ROMs are efficiently built with reduced computing time and limited loss of accuracy compared to a nonlinear reference model.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Mickael Le Bohec, Denis Lemonnier, Didier Saury
Summary: This study introduces a method for solving the radiative heat transfer problem in buildings. The method reduces the calculation time by constructing a representation of the view factors at different scales, making it suitable for routine use in a design perspective.
NUMERICAL HEAT TRANSFER PART A-APPLICATIONS
(2023)
Article
Mechanics
R. Gers, O. Skurtys, N. Thiers, F. Moreau, D. Saury
Summary: This work investigates the influence of cavity depth variation on heat transfers and flow dynamics in a differentially heated cavity with natural convection flow. Three-dimensional numerical simulations are conducted to analyze the impact of the rear and front boundary conditions on the flow topology. The results show that increasing cavity depth enhances local heat transfer and the emergence of vortex structures caused by Gortler instability. However, paradoxically, some characteristics of flow and heat transfer tend to the two-dimensional case value as the cavity gets deeper.
Article
Thermodynamics
A. Weppe, F. Moreau, D. Saury
Summary: This work presents the dynamical and thermal behaviors of turbulent natural convection flow occurring in a cubic cavity. Through experimental measurements and analysis, we observed boundary layer flows, the presence of a recirculating zone, and disturbances in heat transfers. We also found the existence of boundary layer instability and internal gravity waves.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
A. Weppe, F. Moreau, D. Saury
Summary: This paper presents an experimental study on turbulent natural convection air flow inside an enclosure with partially heated inner block. Unsteady boundary conditions are applied on the heated face of the block to simulate industrial unsteady heating or cooling conditions. The maximum Rayleigh number reached is 1.98 x 109, which corresponds to the flow regime encountered in car underhood. A dynamical analysis of the flow is conducted for Rayleigh numbers from 0.25 x 109 to 1.98 x 109, and similarity properties of the ascendant boundary layer are highlighted.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2023)
Article
Thermodynamics
P. Huerta, R. Gers, O. Skurtys, F. Moreau, D. Saury
Summary: This study numerically investigates natural convection flow in a rectangular differentially heated cavity. The aspect ratio of the cavity is 4, the working fluid is air, and the Rayleigh number is 9 x 107 based on the cavity height. A large rectangular obstacle is positioned at the center of the cavity. The effects of obstacle size and a new geometry obtained from the obstacle on flow dynamics and heat transfers are examined.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Materials Science, Multidisciplinary
A. Sghuri, Y. Billaud, L. Signor, D. Saury, X. Milhet
Summary: Silver paste sintering is a die-bonding technology for power electronic modules, with the relationship between joint density and thermal conductivity being an unresolved issue. This study investigates this issue by developing self-standing specimens with microstructures representative of real joints. The thermal conductivity is measured using a 3D flash method, and the relationship between porosity and thermal conductivity is established for different conditions and compared to existing models. The evolution of thermal properties during aging is discussed.
Article
Thermodynamics
Xuan Bach Nguyen, Didier Saury, Denis Lemonnier
Summary: The study investigates the effect of a hot obstacle located on the floor of a cubic cavity in natural convection. The conservation equations are solved using a finite volume method, and the radiative transfer equation is solved using the discrete ordinates method. It was observed that the volume radiation strongly influences the thermal and dynamic fields, breaking the nearly vertical stratification of the temperature field around the plume. Additionally, radiation accelerates the boundary layers near the lateral surfaces and the ceiling and floor.
PROGRESS IN COMPUTATIONAL FLUID DYNAMICS
(2022)
