Abstract:Natural convection heat transfer in inclined square cavity filled with thermo-dependent power-law fluids has been investigated numerically. The enclosure considered here is heated and cooled with uniform fluxes from the horizontal walls, while the verticals ones are adiabatic. The effects of the governing parameters, which are the thermo-dependence number (0 £ m£10) , the flow behavior index (n = 0.6) , the Rayleigh number (Ra =104 ) and the angle of inclination (0° £f £ 120°) , on flow structure and heat transfer characteristics have been examined. Results are presented in the form of treamline and isotherm plots as well as the variation of the Nusselt number under different conditions.

Keywords:Heattransfer; Natural convection; Non-Newtonianfluids; Tilted square cavity; Thermo-dependentBehavior.

Abstract: Two-dimensional steady-state buoyancy driven flows of thermo-dependent shear-thinning power-law fluid confined in a square cavity, submitted to cross uniform heat fluxes, has been conducted numerically using a finite difference technique. The
parameters governing the problem are the thermo-dependence number (0 £ m £ 10) and the ratio between the heat flux imposed on the vertical walls and that imposed on the horizontal ones represented by a (0 £ a £1) , while the flow behavior index n is fixed at
(n = 0.6) and the Rayleigh number at (Ra = 5. 103) . The effects of these parameters on the flow structure and heat transfer characteristics have been analyzed.

Key words: Heat transfer; Natural convection; Non-Newtonian fluids; Numerical study; Square cavity.

Abstract: A numerical study is described for combined forced convection and radiative heat transfer. The humid air supposed to be a perfect gas in a boundary layer approached laminar flow is confined between two coaxial cylinders. The inner cylinder, covered by a thin water film, is assumed to be adiabatic, while the outer is thermally insulated and dry. The numerical model, based on the finite volume technique is used to solve the one dimensional Navier-Stokes and energy equations. The radiative part of this study was solved using the “Ray Tracing” method, associated with the “Statistical Narrow Band Correlated–k” (SNBCK) model. This study has been made of the effect of gas radiation and the influence of dry surface emissivity are presented. Results showed that the gas radiation remains non negligible and acts as an influent factor in the humidification process. Also, increasing the dry surface emissivity results in a rising of the humid surface temperature and the evaporated flow rate.

Keywords: Film evaporation, forced convection, thermal radiation, non-grey gas, SNBCK4 model

Abstract: Solar radiation data are important tools for many areas of research and applications in various engineering and scientific fields including for example climatology, agro meteorology, hydrology and solar energy converting system design. The main objective of the present study is to predict the daily solar radiation and the hourly irradiation on a horizontal surface for the city of Gabès located in the south east of Tunisia. The obtained results are used to develop a Matlab program which can be used in the estimation of the solar radiations for all the city of Tunisia.

Key words: solar radiation, solar energy, daily solar radiation, hourly solar irradiation.

Abstract: In this paper, numerical simulations and experimental validation were carried out to gain an insight into the complex flow field developing around a small wind rotor and to evaluate its performance. We consider the Navier-Stokes equations in conjunction with the standard k-ε turbulence model to study the aerodynamic parameters of a NACA2415 airfoil type wind turbine. These equations are solved numerically to present the local characteristics of the flow and the models tested are implemented using the software "SolidWorks Flow Simulation". Experiments have been also conducted on an open wind tunnel equipped by a small NACA2415 airfoil type wind turbine to validate the numerical results. This will help improving the aerodynamic efficiency in the design of packaged installations of the NACA2415 airfoil type wind turbine.

Key words: NACA2415 airfoil wind turbine, wind tunnel, turbulent flow, aerodynamic structure.