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The logarithmic law of mean temperature profile has been observed in different regions in Rayleigh-B\'enard turbulence. However, how thermal plumes correlate to the log law of temperature and how the velocity profile changes with pressure…

Fluid Dynamics · Physics 2019-10-08 Hong-Yue Zou , Wen-Feng Zhou , Xi Chen , Yun Bao , Jun Chen , Zhen-Su She

The present research proposes a new memory-efficient method using diffusion models to inject turbulent inflow conditions into Large Eddy Simulation (LES) and Direct Numerical Simulation (DNS) for various flow problems. A guided diffusion…

In this dissertation two-dimensional buoyancy-driven flows are investigated. While usually the Navier-Stokes equations are equipped with no-slip boundary conditions here we focus on the Navier-slip conditions that, depending on the system…

Analysis of PDEs · Mathematics 2024-09-25 Fabian Bleitner

We offer a new model for the heat transfer and the turbulence intensity in strongly driven Rayleigh-Benard turbulence (the so-called ultimate regime), which in contrast to hitherto models is consistent with the new mathematically exact heat…

Fluid Dynamics · Physics 2024-07-24 Olga Shishkina , Detlef Lohse

We numerically study the Rayleigh-B\'enard (RB) convection in two-dimensional model emulsions confined between two parallel walls at fixed temperatures. The systems under study are heterogeneous, with finite-size droplets dispersed in a…

Heat transport in highly turbulent convection is not well understood. In this paper, we simulate compressible convection in a box of aspect ratio 4 using computationally-efficient MacCormack-TVD finite difference method on single and…

Fluid Dynamics · Physics 2024-11-18 Harshit Tiwari , Lekha Sharma , Mahendra K. Verma

Rayleigh-Taylor (RT) instability widely exists in nature and engineering fields. How to better understand the physical mechanism of RT instability is of great theoretical significance and practical value. At present, abundant results of RT…

Fluid Dynamics · Physics 2021-07-09 Lu Chen , Huilin Lai , Chuandong Lin , Demei Li

This study presents a new turbulence model for isothermal compressible flows. The model is derived by combining the Favre averaging and the Conservation-dissipation formalism -- a newly developed thermodynamics theory. The latter provides a…

Analysis of PDEs · Mathematics 2025-04-29 Zhiting Ma , Wen-An Yong , Yi Zhu

The non-linear regime of Rayleigh-Taylor instability (RTI) in a radiation supported atmosphere, consisting of two uniform fluids with different densities, is studied numerically. We perform simulations using our recently developed numerical…

High Energy Astrophysical Phenomena · Physics 2013-01-17 Yan-Fei Jiang , Shane W. Davis , James Stone

A model for the structure function constant associated with index of refraction fluctuations in Rayleigh-Benard turbulence is developed. The model is based upon the following assumptions: (1) the turbulence is homogeneous and isotropic at…

Fluid Dynamics · Physics 2023-11-01 Robert A. Handler , Richard J. Watkins , Silvia Matt , K. P. Judd

The theory of turbulent diffusion of chemically reacting gaseous admixtures developed previously (Phys. Rev. E {\bf 90}, 053001, 2014) is generalized for large yet finite Reynolds numbers, and the dependence of turbulent diffusion…

Fluid Dynamics · Physics 2018-05-24 T. Elperin , N. Kleeorin , M. Liberman , A. Lipatnikov , I. Rogachevskii , R. Yu

A pure and incompressible material is confined between two plates such that it is heated from below and cooled from above. When its melting temperature is comprised between these two imposed temperatures, an interface separating liquid and…

Fluid Dynamics · Physics 2020-02-11 Jhaswantsing Purseed , Benjamin Favier , Laurent Duchemin , Eric W. Hester

A simple analytical/numerical model has been developed for computing the evolution, over periods of up to a few hours, of the current and temperature profile in the upper layer of the ocean. The model is based upon conservation laws for…

Atmospheric and Oceanic Physics · Physics 2007-05-23 Alastair D. Jenkins , Brian Ward

This work reports the results of the theoretical investigation of nonlinear dynamics and spiral wave breakup in a generalized two-variable model of cardiac action potential accounting for thermo-electric coupling and diffusion…

Tissues and Organs · Quantitative Biology 2018-11-07 A. Gizzi , A. Loppini , R. Ruiz-Baier , A. Ippolito , A. Camassa , A. La Camera , E. Emmi , L. Di Perna , V. Garofalo , C. Cherubini , S. Filippi

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

We present results of a high resolution numerical study of two dimensional (2d) Rayleigh-Taylor turbulence using a recently proposed thermal lattice Boltzmann method (LBT). The goal of our study is both methodological and physical. We…

Chaotic Dynamics · Physics 2015-05-20 L. Biferale , F. Mantovani , M. Sbragaglia , A. Scagliarini , F. Toschi , R. Tripiccione

To understand turbulent convection at very high Rayleigh numbers typical of natural phenomena, computational studies in slender cells are an option if the needed resources have to be optimized within available limits. However, the…

A cylindrical and inclined jet in crossflow is studied under two distinct velocity ratios, $r=1$ and $r=2$, using highly resolved large eddy simulations (LES). First, an investigation of turbulent scalar mixing sheds light onto the…

Fluid Dynamics · Physics 2020-12-30 Pedro M. Milani , Julia Ling , John K. Eaton

Rapidly rotating Rayleigh-B\'enard convection is studied by combining results from direct numerical simulations (DNS), laboratory experiments and asymptotic modeling. The asymptotic theory is shown to provide a good description of the bulk…

Fluid Dynamics · Physics 2015-06-23 S. Stellmach , M. Lischper , K. Julien , G. Vasil , J. S. Cheng , A. Ribeiro , E. M. King , J. M. Aurnou

We present mesoscale numerical simulations of Rayleigh-B\'enard (RB) convection in a two-dimensional model emulsion. The systems under study are constituted of finite-size droplets, whose concentration Phi_0 is systematically varied from…