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Understanding the coolant thermal hydraulics in rod bundles is essential to the design of nuclear reactors. However, flows with low Reynolds numbers present serious modeling challenges, especially in heat transfer and natural convection.…

Fluid Dynamics · Physics 2023-08-31 Carolina Bourdot Dutra , Elia Merzari

We derive the incompressible Euler equations with heat convection with the no-penetration boundary condition from the Boltzmann equation with the diffuse boundary in the hydrodynamic limit for the scale of large Reynold number. Inspired by…

Analysis of PDEs · Mathematics 2021-04-07 Yunbai Cao , Juhi Jang , Chanwoo Kim

Boundary layers play an important role in controlling convective heat transfer. Their nature varies considerably between different application areas characterized by different boundary conditions, which hampers a uniform treatment. Here, we…

Fluid Dynamics · Physics 2013-03-20 K. Petschel , S. Stellmach , M. Wilczek , J. Lülff , U. Hansen

The effect of rotation on the boundary layers (BLs) in a Rayleigh-Benard (RB) system at a relatively low Rayleigh number, i.e. $Ra = 4\times10^7$, is studied for different Pr by direct numerical simulations and the results are compared with…

Fluid Dynamics · Physics 2011-12-05 Richard J. A. M. Stevens , Herman J. H. Clercx , Detlef Lohse

New insight into the contribution of the microscale vortex evolution towards convection heat transfer in porous media is presented in this paper. The objective is to determine how the microscale vortices influence convection heat transfer…

Fluid Dynamics · Physics 2022-06-01 Ching-Wei Huang , Vishal Srikanth , Andrey V. Kuznetsov

We prove the first rigorous bound on the heat transfer for three-dimensional Rayleigh-B\'enard convection of finite-Prandtl-number fluids between free-slip boundaries with an imposed heat flux. Using the auxiliary functional method with a…

Fluid Dynamics · Physics 2018-04-11 Giovanni Fantuzzi

We investigate the convective cooling of a fluid with a quadratic equation of state by performing three-dimensional direct numerical simulations of a flow with a fixed top-boundary temperature, which is lower than the initial fluid…

Fluid Dynamics · Physics 2021-07-01 Jason Olsthoorn , Edmund W. Tedford , Gregory A. Lawrence

We present mesoscale numerical simulations of Rayleigh-B\'{e}nard convection in a two-dimensional concentrated emulsion, confined between two parallel walls, heated from below and cooled from above, under the effect of buoyancy forces. The…

We establish a theoretical framework for predicting friction and heat transfer coefficients in variable-properties forced air convection. Drawing from concepts in high-speed wall turbulence, which also involves significant temperature,…

Fluid Dynamics · Physics 2024-12-18 Davide Modesti , Sergio Pirozzoli

Treating diffusion and advection/reaction separately is an effective strategy for solving semilinear advection-diffusion-reaction equations. However, such an approach is prone to suffer from order reduction, especially in the presence of…

Numerical Analysis · Mathematics 2025-11-12 Thi Tam Dang , Lukas Einkemmer , Alexander Ostermann

Experimental and numerical data for the heat transfer as a function of the Rayleigh-, Prandtl-, and Rossby numbers in turbulent rotating Rayleigh-Benard convection are presented. For relatively small $Ra ~ 10^8$ and large Pr modest rotation…

Convection is the predominant mechanism by which energy and angular momentum are transported in the outer portion of the Sun. The resulting overturning motions are also the primary energy source for the solar magnetic field. An accurate…

Solar and Stellar Astrophysics · Physics 2018-03-26 Ryan J. Orvedahl , Michael A. Calkins , Nicholas A. Featherstone , Bradley W. Hindman

We study the evolution of a melting front between the solid and liquid phases of a pure incompressible material where fluid motions are driven by unstable temperature gradients. In a plane layer geometry, this can be seen as classical…

Fluid Dynamics · Physics 2019-01-15 Benjamin Favier , Jhaswantsing Purseed , Laurent Duchemin

In this work, we investigate the presence and impact of stable eigenmodes in Rayleigh-B\'{e}nard convection that arises due to a temperature gradient within a fluid system. The nonlinear evolution of the canonical convection system is cast…

Fluid Dynamics · Physics 2025-07-29 Zachary R. Williams , Ava G. Lowe

A Rayleigh-B\'enard cell has been designed to explore the Prandtl (Pr) dependence of turbulent convection in the cross-over range $0.7<Pr<21$ and for the full range of soft and hard turbulences, up to Rayleigh number $Ra\simeq 10^{11}$. The…

Condensed Matter · Physics 2009-11-10 P. -E. Roche , B. Castaing , B. Chabaud , B. Hebral

The dependence of the heat transfer, as measured by the nondimensional Nusselt number $Nu$, on Ekman pumping for rapidly rotating Rayleigh-B\'enard convection in an infinite plane layer is examined for fluids with Prandtl number $Pr = 1$. A…

Fluid Dynamics · Physics 2017-09-13 Meredith Plumley , Keith Julien , Philippe Marti , Stephan Stellmach

A One-Dimensional (1D) Reduced-Order Model (ROM) has been developed for a 3D Rayleigh-B\'enard convection system in the turbulent regime with Rayleigh number $\mathrm{Ra}=10^6$. The state vector of the 1D ROM is horizontally averaged…

Fluid Dynamics · Physics 2019-01-16 M. A. Khodkar , Pedram Hassanzadeh , Saleh Nabi , Piyush Grover

The heat transfer and flow structure in rotating Rayleigh-B\'enard convection are strongly influenced by the Rayleigh ($Ra$), Prandtl ($Pr$), and Rossby ($Ro$) number. For $Pr\gtrsim 1$ and intermediate rotation rates, the heat transfer is…

Fluid Dynamics · Physics 2020-05-14 Yantao Yang , Roberto Verzicco , Detlef Lohse , Richard J. A. M. Stevens

Reaction-diffusion equations are one of the most common mathematical models in the natural sciences and are used to model systems that combine reactions with diffusive motion. However, rather than normal diffusion, anomalous subdiffusion is…

Statistical Mechanics · Physics 2021-04-23 Amanda M Alexander , Sean D Lawley

Rayleigh-B\'enard cells are one of the simplest systems to explore the laws of natural convection in the highly turbulent limit. However, at very high Rayleigh numbers (Ra > 1E12) and for Prandtl numbers of order one, experiments fall into…

Fluid Dynamics · Physics 2012-02-14 Philippe-E. Roche , Frédéric Gauthier , Robert Kaiser , Julien Salort