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Numerical study of natural convective heat transfer of partially heated tall rectangular cavity filled with (Al2O3-water) nanofluid. Two opposing horizontal walls are adiabatic, while the right vertical wall is kept at fixed cold temperature, and the left wall of the cavity heated partially. The effect of Rayleigh number (Ra), Aspect ratio (A), and the volume fractions of nanoparticles (ϕ) on the isotherms, streamline, and the average Nusselt number (Nu) have been investigated. The dimensionless governing equations with the Boussinesq approximation have been solved numerically, by using the finite element approach. The results presented for a wide range of parameters including; (103≤Ra≤105, 5≤A≤10, and 0.02≤ϕ≤0.06). The result shows that; the Nu increase when the effect of Rayleigh number (Ra), and the volume fractions of nanoparticles (ϕ) increasing, and also it increase when the Aspect ratio (A) increasing.

The effect of twisted tape ratio has been studied numerically to promoting a swirl effects inside a long half-length pipe. A constant wall temperature demonstrates solar collector at average temperature conditions for the receiver pipe. The flow simulation adjusted at different range of Reynolds number 1500-7000 and varied twisted tape ratio y=2, 3.3, and 5. The results showed that; when the twisted tape pipe increases (for example at 3.4), the average outlet temperature, heat transfer coefficient, Nusselt number, friction factor, and power losses increases to 64, 65, 28, 14.1, 31 % respectively compared with plain pipe, also the average outlet fluid temperature is maximum from 305 K-322 K at low Reynolds number 1500 for all cases and then will be decreasing with increasing Reynolds number .The results presented in contours of temperature distribution and flow trajectory by axial velocity were accomplished to exam the low Reynolds number in solar applications. It showed that, when the swirl geometry used, which would be effect on the axial velocity for the flow by 10 % more than the cases without twist tape.

In the old new present work cares with change of Reynolds number effect on the hydrodynamic characteristics. The different pitch angle is taken to analysis drag, lift, and pressure coefficients. The goal of these parameters is to understand the nature of the flow over the upper surface of the airfoil since the long laminar boundary layer and transition region have a light point for aerodynamics performance assessment. The results indicated that indicated the improvement in performance is parallel in path with the increasing length of the laminar flow region.

The purpose of this investigation is to determine if adding an isolated cylinder to the domain can improve forced convection in the laminar case of the sudden expansion flow in a two-dimensional channel. The range of the Reynolds number (1-200) and the number of prattle 0.71, the impact of different cross-stream locations (x=10.4,10.8 and 11.2) of the circular cylinder on the flow, and thermal properties of the sudden expansion flow have been computationally studied (air). COMSOL Multiphysics is utilized to address the governing continuity, Navier-Stokes, energy equation of energy, and the necessary boundary conditions. Although streamline and isotherm profiles have been used to describe the flow and thermal fields, the temperature dependence of the flow viscosity and thermal conductivity has not been taken into account. The findings presented here demonstrate an improvement in the peak Nusselt value when a circular cylinder is used in comparison to the unobstructed condition.