Abstract. The problem of Rayleigh–Bénard convection with internal heat sources and a variable gravity field is treated. For the case of stress-free boundary conditions, it is proved that the principle of exchange of stabilities holds as long as the product of gravity field and the integral of the heat sources is nonnegative throughout the layer. The proof is based on the idea of a positive oper...

Rayleigh-Bénard convection with internal heat sources and a variable gravity field is treated with no-slip boundary conditions. It is proved that the principle of exchange of stabilities holds at all Prandtl numbers, as long as the gravity field and the integral of the heat sources both have the same sign. The proof is based on the idea of a positive operator, and uses the positivity properties...

There is a gap between the population growth and protein supply in many tropical countries where per capita income is low and the majority of people consume less protein than a daily standard for recommended protein intake. Poultry egg production remains the fastest route to bridging the protein demand-supply gap in these regions. However, poultry are faced with heat stress in the tropics which...

7 Generation of entropy and transfer of heat during forced convection of a nanofluid through a partially-filled 8 porous channel are investigated theoretically. The problem includes a fully developed flow in a channel with a 9 central porous insert and under constant heat flux boundary condition. The system is assumed to be under local 10 thermal non-equilibrium and the solid and nanofluid phas...

In the present study, an unlooped pulating heat pipe has been considered with two liquid slugs and three neighboirng vapor plugs.The governing equations such as momentum, energy and mass equations are solved explicitly except the energy equation of liquid slugs.The aim of the present study is to calculate the entropy generation through the performance of a pulsating heat pipe. Additionally, the...

In this work, analysis of heat transfer in porous fin with temperature-dependent thermal conductivity and internal heat generation is carried out using Chebychev spectral collocation method. The numerical solutions are used to investigate the influence of various parameters on the thermal performance of the porous fin. The results show that increase in convective parameter, porosity parameter, ...

Genetic algorithms are employed to optimize dimensionless temperature in nonlinear heat conduction problems. Three common geometries are selected for the analysis and the concept of minimum entropy generation is used to determine the optimum temperatures under the same constraints. The thermal conductivity is assumed to vary linearly with temperature while internal heat generation is assumed to...

wear is a complicated phenomenon caused by the relative movement of two contacting surfaces compressed together by a normal force. prediction of the wear, in most cases, requires various experiments and microstructural characterization of the contacting surfaces. mathematical models based on physical concepts could provide considerable help in understanding the physical behavior and hence the p...