Article
Mechanics
Jian-Chao He, Yun Bao, Xi Chen
Summary: Direct numerical simulation (DNS) is conducted for non-slip two dimensional (2D) Rayleigh-Benard convection (RBC) with a wide range of Rayleigh number (Ra up to 10^13), Prandtl number Pr 1/4 0.7, and aspect ratio gamma= 1. The thermal dissipation rate shows an evident scaling transition at Ra asymptotic to 10^9. The mean temperature gradient in the thermal boundary layer is the dominant contribution to the transition. The Nusselt number also exhibits the transition at Ra asymptotic to 10^9. Rating: 7/10.
Article
Mechanics
Shashwat Bhattacharya, Mahendra K. Verma, Arnab Bhattacharya
Summary: A multivariate regression model and a neural network model were developed in this paper to predict the Reynolds number and Nusselt number in turbulent thermal convection. By comparing with earlier models, it was found that the machine-learning models in this work provided the best match with the experimental and numerical results.
Article
Mechanics
Sebastian Moller, Theo Kaeufer, Ambrish Pandey, Joerg Schumacher, Christian Cierpka
Summary: Turbulent superstructures in horizontally extended three-dimensional Rayleigh-Benard convection flows are investigated in controlled laboratory experiments in water at Prandtl number Pr = 7. The experimental results confirm that the superstructure patterns are an important backbone of the heat transfer.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Physics, Multidisciplinary
Felix Schindler, Sven Eckert, Till Zuerner, Joerg Schumacher, Tobias Vogt
Summary: In highly turbulent liquid metal convection experiments, the large-scale flow structure and the turbulent transfer of heat and momentum were directly measured. It was found that the aspect ratio has a significant impact on the scaling laws for heat and momentum transfer.
PHYSICAL REVIEW LETTERS
(2022)
Review
Mechanics
Robert E. Ecke, Olga Shishkina
Summary: Rotation with thermally induced buoyancy is an important factor in governing various astrophysical and geophysical processes. The rotating Rayleigh-Benard convection (RRBC) experimental system exhibits the features of rotation and buoyancy, and its dynamics are affected by factors such as Rayleigh and Rossby numbers. The RRBC system provides valuable insights into geophysical and astrophysical phenomena, and this review discusses heat transport scaling approaches and related effects.
ANNUAL REVIEW OF FLUID MECHANICS
(2023)
Article
Physics, Fluids & Plasmas
Andres J. Aguirre Guzman, Matteo Madonia, Jonathan S. Cheng, Rodolfo Ostilla-Monico, Herman J. H. Clercx, Rudie P. J. Kunnen
Summary: This study numerically investigates the flow regimes of rotating Rayleigh-Benard convection from a statistical viewpoint. Different flow patterns, such as steady cells, convective Taylor columns, plumes, large-scale vortices, and rotation-affected convection, are observed under varying parameters. The statistical analysis of convective heat transfer and thermal mixing provides insights into the behavior of the flow.
PHYSICAL REVIEW FLUIDS
(2022)
Article
Mechanics
Bo-Fu Wang, Jin-Lei Wu, Jian-Zhao Wu, Kai Leong Chong, Yu-Lu Liu, Quan Zhou
Summary: In this study, we experimentally investigated the heat transfer and flow characteristics in a rectangular cell with built-in lattice channels. Three different models with varying channel sizes and positions and the classical Rayleigh-Benard convection were studied. The results showed that the inclusion of channels with appropriate lengths and positions can effectively regulate the flow near the boundary layer and in the bulk, leading to significant enhancements in heat transfer.
Article
Mechanics
Marcel Wedi, Dennis P. M. van Gils, Eberhard Bodenschatz, Stephan Weiss
Summary: This study reports turbulent thermal convection experiments in a rotating cylinder, revealing changes in heat transport and temperature field at different rotation rates, as well as proposing interpretations for two transition points in the rotation rates. The research findings provide insights into the behavior of turbulent thermal convection in a rotating system.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Shashwat Bhattacharya, Mahendra K. Verma, Ravi Samtaney
Summary: In this paper, the GL model is extended for predicting Reynolds number and Nusselt number in turbulent Rayleigh-Benard convection. Functional forms for dissipation rates prefactors are used, and machine learning is applied to determine revised predictions that show better agreement with past results in a three-dimensional unit box setting.
Article
Mechanics
Guang-chun Xu, Qi Wang, Zhen-hua Wan, De-jun Sun
Summary: Investigated rough-surface Rayleigh-Benard convection using direct numerical simulations in two-dimensional cells with different levels of roughness, showing that roughness affects convective behavior and leads to different regimes under high Rayleigh numbers. Additionally, a correlation between thermal dissipation rate and convective structures was found.
JOURNAL OF HYDRODYNAMICS
(2021)
Article
Mechanics
Anna Hertlein, Ronald du Puits
Summary: This study presents measurements of the thermal dissipation rate in turbulent Rayleigh-Benard convection using a four-thermistor temperature gradient probe. The thermal dissipation rate decreases monotonically with distance from the plate, with maximum near the wall and at the highest Rayleigh number. The normalized thermal dissipation rate scales with an exponent of about 0.29 with the Rayleigh number and is higher in the boundary layer than in the bulk region.
Article
Physics, Multidisciplinary
P. Urban, T. Kralik, M. Macek, P. Hanzelka, T. Veznik, L. Skrbek
Summary: This experimental study focused on the role of boundary conditions in turbulent thermal convection of cryogenic helium gas at high Rayleigh numbers. Switching between constant heat flux and constant temperature boundary conditions resulted in significant changes in temperature fluctuations at the bottom plate, while top plate dynamics and bulk convective flow remained unaffected. There were no observable changes in Reynolds number scaling, Nusselt number scaling, or rate of direction reversals of large scale circulation within the experimental accuracy.
Article
Mechanics
Wei Zhang, Manman Qiao, Bingchuan Nie, Feng Xu
Summary: The study investigates the period bubbling bifurcation and transition to a chaotic state of a convective flow on the top-open cylinder beneath heating using direct numerical simulation. The results show a complex route of transitioning to chaotic state with successive bifurcations as the Rayleigh number increases. An interesting phenomenon is observed where the convective flow may change from periodic back to steady state within a certain range of Rayleigh numbers.
Article
Mechanics
Yun-Bing Hu, Yi-Chao Xie, Ke-Qing Xia
Summary: This study experimentally investigates the effect of centrifugal force on turbulent rotating Rayleigh-Benard convection. The results show that the centrifugal effect depends on the Rayleigh number and flow states, providing important insights for predicting heat transport.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Physics, Fluids & Plasmas
Ambrish Pandey, Joerg Schumacher, Katepalli R. Sreenivasan
Summary: This study examines convection in the Sun at high Rayleigh numbers and low Prandtl numbers, and finds that turbulent Prandtl number (Prt) increases with decreasing Pr in both Oberbeck-Boussinesq (OB) and non-Oberbeck-Boussinesq (NOB) convection scenarios. This suggests that convective flows in astrophysical settings behave effectively as in high-Prandtl-number turbulence.
PHYSICAL REVIEW FLUIDS
(2021)
Article
Physics, Fluids & Plasmas
Jun-Qiang Shi, Hao-Yuan Lu, Shan-Shan Ding, Jin-Qiang Zhong
PHYSICAL REVIEW FLUIDS
(2020)
Article
Multidisciplinary Sciences
Kai Leong Chong, Jun-Qiang Shi, Guang-Yu Ding, Shan-Shan Ding, Hao-Yuan Lu, Jin-Qiang Zhong, Ke-Qing Xia
Article
Multidisciplinary Sciences
Shan-Shan Ding, Kai Leong Chong, Jun-Qiang Shi, Guang-Yu Ding, Hao-Yuan Lu, Ke-Qing Xia, Jin-Qiang Zhong
Summary: This study demonstrates, through experiments and numerical simulations, the outward motion of warm and lighter vortices in rotating thermal convection, driven by long range, scale-free vortex correlations. The mechanism behind this counterintuitive effect is revealed, providing insights into the dynamics of vortices widely present in nature.
NATURE COMMUNICATIONS
(2021)
Article
Mechanics
Shan-Shan Ding, Hong-Lin Zhang, Dong-Tian Chen, Jin-Qiang Zhong
Summary: This study presents experimental research on pattern formation and selection in rapidly rotating convection using spatial periodic forcing. The researchers found that symmetric convection patterns in the form of regular vortex lattices can be observed near the onset of convection, when the periodicity of the external forcing is close to the intrinsic vortex spacing. By exploring the phase diagram, the optimal experimental settings were identified for which the vortex patterns best match the external forcing.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Engineering, Mechanical
Shan-Shan Ding, Marco Placidi, Matteo Carpentieri, Alan Robins
Summary: This study investigates the development of the internal boundary layer (IBL) induced by a surface roughness discontinuity, where the downstream surface has a higher roughness length than the upstream surface. The analysis shows good agreement between the IBL development and the diffusion model in the log-law region for neutrally-stratified boundary layers. However, the model over-predicts the IBL growth in the outer layer and further reductions are found for stably-stratified boundary layers.
EXPERIMENTS IN FLUIDS
(2023)