We present a numerical study of the flow states and reversals large-scale circulation (LSC) in two-dimensional circular Rayleigh-B\'enard cell. Long-time direct simulations are carried out Rayleigh number ($Ra$) range $10^{7} \le Ra 10^{8}$ Prandtl ($Pr$) $2.0 Pr 20.0$. found that new, long-lived, chaotic state exists, addition to commonly observed (the LSC clockwise counterclockwise directions...

In this paper, natural convection heat transfer of CuO-water Nanofluid within a wavy-walled cavity and subjected to a uniform magnetic field is examined by adopting the lattice Boltzmann model. The left wavy wall is heated sinusoidal, while the right flat wall is maintained at the constant temperature of Tc. The top and the bottom horizontal walls are smooth and insulated against heat and mass....

This study proposes the dual reciprocity boundary element (DRBEM) solution for full magnetohydrodynamics (MHD) equations in a lid-driven square cavity. MHD equations are coupled with the heat transfer equation by means of the Boussinesq approximation. Induced magnetic field is also taken into consideration. The governing equations in terms of stream function, temperature, induced magnetic field...

A numerical study of Rayleigh-Benard convection in an infinite fluid layer (Pr=0.71) is performed using large eddy simulation (LES) of the Navier-Stokes equations with the Boussinesq approximation. We present results in the ’hard turbulence’ regime (2.10 < Ra < 2.10). The LES modelling uses the mixed scale diffusivity model, that we have originally developed in the case of the differentially he...

This study presents direct numerical simulations of natural convection for air (Pr = 0.709) in a vertical channel driven by differentially heated walls at Rayleigh numbers (Ra) up to 2.0 × 107. The present data is validated with that from Versteegh and Nieuwstadt [9] for Ra = 5.0 × 106. Using the present data for higher Ra, we appraise and compare the various proposed scaling laws for the mean ...

Natural convection in a cubical cavity heated from below with perfectly conducting sidewalls is investigated numerically. A parameter continuation procedure based on a Galerkin spectral method was applied to obtain the bifurcation diagrams for steady flow solutions over the region of Rayleigh numbers Ra 1.5× 10 at Prandtl numbers Pr =0.71 and 130. In both cases, the bifurcation diagrams were mo...

A new regime of turbulent convection has been reported nearly one decade ago, based on global heat transfer measurements at very high Rayleigh numbers. We examine the signature of this “Ultimate Regime” from within the flow itself. A systematic study of probe-size corrections shows that the earlier temperature measurements within the flow were altered by an excessive size of thermometer, but no...

Measurements of the Nusselt number Nu and of temperature variations DeltaTb in the bulk fluid are reported for turbulent Rayleigh-Bénard convection of a cylindrical sample. They cover the Rayleigh-number range 10(9) less than or similar to Ra less than or similar to 3x10(14) using He (Prandtl number Pr=0.67), N2 (Pr=0.72) and SF6 (Pr=0.79 to 0.84) at pressures up to 15 bars and near-ambient tem...