The effect of radiation on laminar and turbulent mixed convection heat transfer of a semitransparent medium in a square enclosure was studied numerically using the Finite Volume Method. A structured mesh and the SIMPLE algorithm were utilized to model the governing equations. Turbulence and radiation were modeled with the RNG k-ε model and Discrete Ordinates (DO) model, respectively. For Richar...

By tailoring the geometry of the upper boundary in turbulent Rayleigh-Bénard convection we manipulate the boundary layer-interior flow interaction, and examine the heat transport using the lattice Boltzmann method. For fixed amplitude and varying boundary wavelength λ, we find that the exponent β in the Nusselt-Rayleigh scaling relation, Nu − 1 ∝ Ra, is maximized at λ ≡ λmax ≈ (2π) , but decays...

Local convective heat transfer coefficients were measured on a two-diameter long cylinder in axial flows of air at conditions unexplored so far, by using thermochromic liquid crystals (TLC) coated on an electrically heated strip-foil consisting bonded to the external surfaces. The Reynolds numbers (Re) based on the cylinder diameter were between 8.9 · 10 and 6.17 · 10, and the flow in front of ...

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...

Published experiments on natural turbulent convection in cryogenic (4)He gas show contradictory results in the values of Rayleigh number (Ra) higher than 10(11). This paper describes a new helium cryostat with a cylindrical cell designed for the study of the dependence of the Nusselt number (Nu) on the Rayleigh number (up to Ra approximately 10(15)) in order to help resolve the existing controv...

A one-dimensional divergence of the monochromatic heat flux for wall-affected attenuating thingas, is developed from general considerations. Here Ebl. K~ cy and r, respectively denote the monochromatic values of the emissive power, absorption coefficient of gas, wall emissivity and optical thickness; , E, is the second exponential integ-ral, y the -4' coordinate normal to boundary. infinite geo...

A theoretical analysis of the influence temperature and nanoparticle concentration on free convection heat transfer from a horizontal tube immersed in an unbounded nanofluid was presented. The Nusselt (Nu) number coefficient were parameters intensity convective transfer. For convection, Nu function Rayleigh (Ra) Prandtl (Pr) number. functions thermophysical properties nanofluids. nanofluids var...

[1] Heat flow measurements colocated with seismic data across 106 Ma seafloor of the Madeira Abyssal Plain (MAP) reveal variations in seafloor heat flow of ±10–20% that are positively correlated with basement relief buried below thick sediments. Conductive finite element models of sediments and upper basement using reasonable thermal properties are capable of generating the observed positive co...

We report on the influence of rotation about a vertical axis on heat transport by turbulent Rayleigh–Bénard convection in a cylindrical vessel with an aspect ratio Γ ≡ D/L = 0.50 (D is the diameter and L the height of the sample) and compare the results with those for larger Γ . The working fluid was water at Tm = 40 ◦C where the Prandtl number Pr is 4.38. For rotation rates Ω . 1 rad s−1, corr...

The paper presents chosen experimental and model methods of investigating heat transfer in a steel porous charge. results this investigation provide information on both the qualitative quantitative course analysed processes exchange. parameters which characterise phenomenon manner, among others, are: effective thermal conductivity kef, contact resistance Rct Nusselt number Nu. It has been estab...