The Flying V is a flying-wing aircraft that has 20% less cruise drag than a modern tube-and-wing aircraft. The integration of the over-the-wing engine is not trivial due to the strong aerodynamic interaction between the wing and inlet. Prior to integrating the engine, the aerodynamics of the Flying V are studied with a Reynolds-averaged Navier-Stokes (RANS) solver using a finite volume mesh. Engine dimensions are sized through rubber sizing for the take-off thrust rating. The analysis focuses on the flow characteristics on the upper surface of the wing, particularly in the region where the engine could be located. Forces and pressure changes induced at different angles of attack and flight conditions are studied. Subsequently, the evolution of the boundary layer at different locations is analyzed to understand the flow that the engine would face at the inlet. For the defined inlet dimensions, the inlet distortion is evaluated at various locations on the wing. Preferred regions for engine placement and integration approaches are proposed and discussed to maximize the engine inlet performance at on-design and off-design conditions.@en

Aerodynamic research on Mars for the past few decades has increased in the development of optimum aerial vehicles for Mars. The current research aims to study the aerodynamics of a triangular airfoil in Mars atmospheric conditions and understand the future regions of flow improvement. A numerical investigation using a Finite Volume Solver has been performed for 0° to 16° angles of attack at low and high flow velocities. Low flow velocities ranging from Re = 3,000 to 7,000 have been considered for the investigation. The nonlinearity in Cl appears as the separation bubble begins to approach the apex on the suction surface. Apart from the separation bubble, a flow recirculation zone is generated for low and high Re. at α = 16°. The highest aerodynamic performance is at α = 6°.@en

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.

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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.

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A numerical study has been carried out on the two-dimensional flow past a circular cylinder. In this case, a splitter plate is provided at the rear stagnation point in the downstream direction. ansys fluent has been used to carry out the numerical simulations based on finite volume method approach. Grid independence was achieved and the numerical model was validated with results available in open literature at Reynolds numbers of 100, 5000, and 100,000 respectively. In the present investigation, the characteristics of vortex shedding due to the presence of splitter plate in the circular cylinder were investigated. The main focus of this research was to find the optimal splitter plate length for low, moderate, and high Reynolds numbers. It was observed that at low, moderate, and high Reynolds numbers, the drag coefficient (cd) for optimal plate length decreased drastically as compared to the baseline circular cylinder case. Moreover, the fluctuating nature of lift coefficient (cl) had also ceased. This research work has a good potential to decrease time-varying structural loads on bluff bodies by decreasing the vortex shedding frequency and consequently decreasing drag. The scope of our research extends to structures of bridges and large vehicles, radiator pipes of heat exchangers, landing gears of aircraft, and many more.@en

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.

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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.

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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.

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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.

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Conference: 6th National Symposium on Shock Waves, Feb 26-28, 2020 At: IIT Madras, Chennai@en

Application of moving surface boundary layer control technique has been confined to relatively high Reynolds numbers. The present paper reports a numerical study of application of the above flow technique in the ultra-low Reynolds number range. A two dimensional incompressible unstructured grid based Navier Stokes solver has been used for conducting the numerical studies. Moving surface has been applied at three different portions on the airfoil surface, firstly, in the form of a rotating leading edge portion of the airfoil, secondly, a continuous moving surface from leading edge of airfoil to 57% of the chord along the leeward surface of the airfoil and thirdly a continuous moving surface from leading edge to 97% of the chord along the leeward surface of the airfoil. All the moving surface configurations show improvement of aerodynamic performance of the airfoil through enhancement of lift and decrement of drag as compared to a fixed surface one.@en