This paper reports the numerical determination of the entropy generation due to heat transfer, mass transfer and fluid friction in steady state for laminar double diffusive convection, in an inclined enclosure with heat and mass diffusive walls, by solving numerically the mass, momentum, species conservation and energy balance equations, using a Control Volume Finite-Element Method. The influences of the inclination angle, the thermal Grashof number and the buoyancy ratio on total entropy generation were investigated. The irreversibilities localization due to heat transfer, mass transfer and fluid friction is discussed for three inclination angles at a fixed thermal Grashof number.

This paper analyzes heat transfer and fluid flow of natural convection in inclined cavity filled with CuO–water nanofluid and differentially heated. Conservation of mass, momentum, and energy equations are solved numerically by a control volume finite-element method using the SIMPLER algorithm for pressure–velocity coupling. The Prandtl number is fixed at 7.02, corresponding to water. Aspect ratio and solid volume fraction are varied from 0.5 to 4 and from 0% to 4%, respectively. The inclination angle is varied from 0° to 90° and used as a control parameter to investigate flow mode-transition and the accompanying hysteresis phenomenon (multi-steady solutions). It is found that the efficiency of heat transfer is improved by the addition of nanoparticles into base fluid; however, there is an optimum solid volume fraction that maximizes the heat transfer rate. Numerical results show also that the diameter of solid particle is an important parameter that affects the heat transfer efficiency; its impact is more important than the concentration itself. Effects of inclination angle on streamlines and on thermal boundary layer are presented. Combined effects of aspect ratio and inclination angle on heat transfer and hysteresis region are analyzed.

Heat transfer and vortex shedding behind a square cylinder in a laminar channel flow under a magnetic field is conducted numerically. Computations were carried out for different Reynolds and Hartmann numbers ranging from 80 to 250 and from 0 to 4, respectively at a fixed blockage ratio p= h/H = 1/4. The governing equations are solved with a control volume finite element method adapted to the staggered grid. From the investigation of the periodic flow fields, it is found that, through forced convection, both drag and lift coefficients are clearly damped by the magnetic field leading to the stabilization of the square cylinder. It has been found also that the application of a magnetic field to the vortex shedding flow can lead to a transition to symmetric flow. The critical Hartmann number Ha_c characterizing this transition can be correlated by a linear relationship with the Reynolds number as: Ha_c=0.0239.Re-1.118. A discussion about heat transfer under the magnetic field is also presented.