We perform two-dimensional direct numerical simulations to study the effect of porous media on global transport properties and flow structures in Rayleigh–Bénard (RB) convection at different Prandtl numbers. The are carried out a square RB cell with uniformly placed circular obstacles, where porosity spans between ϕ=1 ϕ=0.75 Rayleigh number Ra fixed 108, two high numbers (10,4.3) low (0.03,0.1)...

We present experimental and theoretical results near the onset of the Rayleigh-Bénard convection with rotation about a vertical axis in a fluid with a Prandtl number sigma close to 0.18. In the experiment we used a H2-Xe gas mixture with a separation ratio Psi=0.22 and a Lewis number L=1.22 at various pressures and dimensionless rotation rates Omega up to 400. On the basis of a standard weakly ...

We model buoyancy-driven convection with chimneys – channels of zero solid fraction – in a mushy layer formed during directional solidification of a binary alloy in two dimensions. A large suite of numerical simulations is combined with scaling analysis in order to study the parametric dependence of the flow. Stability boundaries are calculated for states of finite-amplitude convection with chi...

The pattern and style of mantle convection govern the thermal evolution, internal dynamics, and large-scale surface deformation of the terrestrial planets. In order to characterize the nature of heat transport and convective behaviour at Rayleigh numbers, Ra, appropriate for planetary mantles (between 104 and 108), we perform a set of laboratory experiments. Convection is driven by a temperatur...

An inÿnite uid with a vertical cubic temperature proÿle in the absence of uid motion is considered as a model for penetrative convection in which a central unstably stratiÿed uid layer is bounded above and below by stably stratiÿed layers. Turbulence statistics from direct and large eddy numerical simulations for the mean temperature gradient, the velocity and temperature variances and the heat...

Vibrational mixed convection inside an open-ended cavity filled with a porous medium is investigated in this work. Vertical vibration on the left wall and buoyancy induced flow are considered. The effect of variations in governing parameters, such as vibrational Reynolds number, modified Rayleigh number, and the Darcy number on streamlines, isotherms, and the average Nusselt number is discussed...

Abstract

Nowadays there are wide possibilities to perform numerical studies of turbulent natural convection flows on the base of 3D unsteady formulations [1]. Direct Numerical Simulation (DNS) is the most attractive and reliable approach for getting a detailed knowledge on convection [2, 3]. However, DNS applications are practically limited by the case of simplified geometry and/or the Rayleigh numbers ...