The phenomenon of pressure drop and the heat transfer for single-phase microelectronic pin fin heat sinks has been analyzed numerically for many varying pin fin shapes. The present study is based on cooling the pin fins by forced air convection using ANSYS Fluent software. The primary intents of this study focus on maximum heat transfer and minimum flow resistance in pin fins. The aerodynamic efficiency of fins with varying shapes is analyzed to obtain the best-optimized shape for pin fins of heat sinks. The staggered rounded leading edges pin fin has a better quality factor (QF) with low pumping power and the pressure drop for the inlet flow velocities are higher than 4 m/s. Conic sections of pin fins with staggered configurations have been observed to provide better aerodynamic efficiency for Reynolds number ranging 450–900 whereas rounded leading edge of pin fin of heat sinks provides better aerodynamics efficiency for Reynolds numbers above 900.

Rayleigh Taylor instability has been investigated numerically and experimentally by many researchers for more than a century for studying various properties. The unstable interface between the two fluids of varying density with the fluid of higher density being superposed over the fluid with lower density has been studied using various experiments and numerical models. In the recent decades the analysis was more focused on internal conditions, properties and turbulence as the experiments could be designed with more precision and advanced technologies. Lot of research has been done at varying Atwood number which is ratio of difference in the densities of fluids to the sum of fluid densities. This phenomenon happens on the surface of an expanding bubble deep-water, in nuclear explosion, astrophysics. In this review, authors have discussed the understanding of the instability and research done by some of the researchers and also have discussed some of topics which could be investigated further.

Finite volume method for solving the Navier stokes equation is employed for studying 2D incompressible flow around an array of three cylinders placed in a staggered arrangement at two Reynolds numbers 100 and 200. Numerical simulations have been performed for the configurations having three cylinders of equal diameter for varying the longitudinal and transverse gaps. The transverse gap is varied in the first case (T = 0.75D, 1.5D, and 3D) to study the effects on the wake of the cylinders. The second analysis has been performed for the configurations having three cylinders of unequal diameters (D = 0.5D and 1.5D) by varying the diameter of the cylinders in staggered arrangement. The coefficient of forces has been analyzed for this configuration and compared with the results of the simulation of isolated cylinder. The authors have tried to understand the flow behavior in the simulation from the vorticity contours and the streamlines. The complex flow pattern due to mutual interaction between the wakes of the cylinders has been studied based on the varying transverse and the longitudinal distance.

Nanofluid flow over a backward facing step was investigated numerically at low Reynolds number and the heat transfer was analyzed and reported. Al ₂O ₃–H ₂O nanofluids of different volume fractions ( (Formula presented.) = 1–5%) were used as the material with uniform heat flux (UHF) of 5000 W/m ² at bottom wall for Reynolds number 200–600. The backward facing step of two geometries was investigated for two expansion ratios, 1.9432 and 3.5. The SIMPLE algorithm was used in the finite volume solver to solve the Naiver–Stokes equation. Temperature difference at inlet and boundaries, heat transfer coefficient, Nusselt number, coefficient of skin friction, and temperature contours were reported. The results show that when nanofluids are used, the coefficient of heat transfer and Nusselt number increased at all volume fractions and Reynolds number for both the expansion ratios. The coefficient of heat transfer at (Formula presented.) = 5% was higher by 63.11% and 9.66% than the pure water for ER = 1.9432 and ER = 3.5. At (Formula presented.) = 5%, the outlet temperature for the duct decreased by 10 K and 5 K when compared to the pure water for ER = 1.9432 and ER = 3.5. Coefficient of skin friction and outlet temperature decreased for both the volume fractions in both the expansion ratios.

Nanofluid flow over a backward facing step was investigated numerically at low Reynolds number and the heat transfer was analyzed and reported. Al ₂O ₃–H ₂O nanofluids of different volume fractions ( (Formula presented.) = 1–5%) were used as the material with uniform heat flux (UHF) of 5000 W/m ² at bottom wall for Reynolds number 200–600. The backward facing step of two geometries was investigated for two expansion ratios, 1.9432 and 3.5. The SIMPLE algorithm was used in the finite volume solver to solve the Naiver–Stokes equation. Temperature difference at inlet and boundaries, heat transfer coefficient, Nusselt number, coefficient of skin friction, and temperature contours were reported. The results show that when nanofluids are used, the coefficient of heat transfer and Nusselt number increased at all volume fractions and Reynolds number for both the expansion ratios. The coefficient of heat transfer at (Formula presented.) = 5% was higher by 63.11% and 9.66% than the pure water for ER = 1.9432 and ER = 3.5. At (Formula presented.) = 5%, the outlet temperature for the duct decreased by 10 K and 5 K when compared to the pure water for ER = 1.9432 and ER = 3.5. Coefficient of skin friction and outlet temperature decreased for both the volume fractions in both the expansion ratios.

Gurney flap has been used to increase lift in varied types of wings used in aerial vehicles. It is also preferred as it increases pressure on the pressure side of the airfoil thus increasing the lift. Gurney flaps delay the onset of boundary layer separation in fluid flows. In the present research, analysis is performed on NACA4412 airfoil attached with gurney flap of different lengths with respect to chord lengths at 0°, 4° and 8° angles of attack. Ground effect phenomenon is also done at different height regime for different height to chord ratio through computational fluid dynamics (CFD). Analysis is carried out and coefficient of lift, drag, airfoil performance and pressure distribution is studied. In gurney flap, the lift force increases with decreasing ground clearance due to pressure region created under the airfoil. Phenomena of gurney flap are applicable for increase in coefficient of lift during the takeoff of the aircraft.