We prove a new upper bound on the vertical heat transport in Rayleigh-Bénard convection of the form c Ra 1 3 (lnRa) 2 3 under the assumption that the ratio of Prandtl number over Rayleigh number satisfies Pr Ra ≥ c0 where the non-dimensional constant c0 depends on the aspect ratio of the domain only. This new rigorous bound agrees with the (optimal) Ra 1 3 bound (modulo logarithmic correction) ...

This paper presents the results of an experimental investigation of heat transfer to the airflow in the square duct. The main purpose of this study is influence of square ducts on the convective heat transfer mechanism. Under this investigation friction factor and the Nusselt Number were calculated. The reason that square ducts increase the fluid flow turbulence near the wall and also increase ...

The objective of present research is to examine the thermal radiation effect in three-dimensional mixed convection flow of viscoelastic fluid. The boundary layer analysis has been discussed for flow by an exponentially stretching surface with convective conditions. The resulting partial differential equations are reduced into a system of nonlinear ordinary differential equations using appropria...

Results from direct numerical simulations for three dimensional Rayleigh-Bénard convection in a cylindrical cell of aspect ratio 1/2 and Pr = 0.7 are presented. They span five decades of Ra from 2× 10 to 2× 10. Good numerical resolution with grid spacing ∼ Kolmogorov scale turns out to be crucial to accurately calculate the Nusselt number, which is in good agreement with the experimental data b...

Abstract—An analysis is carried out to investigate the effect of magnetic field and heat source on the steady boundary layer flow and heat transfer of a Casson nanofluid over a vertical cylinder stretching exponentially along its radial direction. Using a similarity transformation, the governing mathematical equations, with the boundary conditions are reduced to a system of coupled, non –linear...

in the present paper, the flow and heat transfer of two types of nanofluids, namely, silver-water and silicon dioxide-water, were theoretically analyzed over an isothermal continues stretching sheet. to this purpose, the governing partial differential equations were converted to a set of nonlinear differential equations using similarity transforms and were then analytically solved. it was found...

We investigate the influence of the thermal properties of the boundaries in turbulent Rayleigh-Bénard convection on analytical bounds on convective heat transport. Using the Doering-Constantin background flow method, we systematically formulate a bounding principle on the Nusselt-Rayleigh number relationship for general mixed thermal boundary conditions of constant Biot number η which continuou...

Developing next generation transient heat exchangers is a transformative technology for efficient ther-mal management of advanced power electronics and electric machines (APEEM) inside hybrid electric,electric, and fuel cell vehicles as well as renewable energies (wind, solar, tidal). Optimal design criteriafor such dynamic heat exchangers should be achieved through addressing inter...

The study scrutinizes the effect of convective heating on magnetohydrodynamic (MHD) stagnation point flow and heat transfer of upper-convected Maxell fluid p ast a s tretching s heet i n t he p resence o f n anoparticles. T he m odel u sed i n t he s tudy i ncludes t he e ffect o f B rownian m otion and thermophoresis parameters. The non-linear governing equations and their boundary conditions ...