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Abstract: In this paper, an attempt has been made to study the thermal and fluid flow behavior of Al2O3–water nanofluid, independent of any external surface influences due to conventional surface heating methods. This has been achieved through natural convection flow induced by volumetric heat generation through microwave heating. Both experimental and numerical investigations were carried out and the numerical results were validated with the experimental data. Numerical simulations were carried out by single-phase and two-phase (Eulerian–Lagrangian) modeling approaches. The effects of nanoparticles in the base fluid, various particle forces and concentration dependence on the hydrodynamics and thermal behavior are presented through isotherms, stream function and time evolution of the fluid flow. The present studies demonstrate that additional fluid flow behavior in nanofluids is induced by the heated nanoparticles due to particle migration effects. [Copyright &y& Elsevier]

Abstract: This paper presents a method developed for determining temperature distribution in a semi-analytical way within tri-dimensional solid-state circuits and packaged devices in steady state conditions. The method is an efficient route to investigate large ranging sized structures with an arbitrary complex layout composed of multiple material layers and localized heat sources. The method, called the Discrete Boundary Resistance (DBR), consists in decomposing the structure into layers of different sizes to develop the temperature solution as a Double Fourier Series after subdividing the contact boundaries into discrete elements. The solution is expressed as a function of thermal resistance attached to the contact boundaries connected to a temperature reference. The performance of the method has been studied in regards with a three-dimensional device involving a non-uniform distribution of voids between layers. Computational time was found to be shorter than ones achieved with the Finite Element method. [Copyright &y& Elsevier]