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A numerical computation was performed of an oblique shock wave impinging on turbulent boundary layer developing on a flat surface. The free stream flow was at M∞ = 2.0 with unit Reynolds number, Re = 10.5x106 m-1. A wedge having an angle of 8° with the free stream flow was used to generate the oblique shock wave. Three dimensional Reynolds averaged Navier-Stokes (RANS) steady simulation with k-ω SST turbulence model was used. The numerically obtained results were validated with experimental data obtained at same flow conditions. Periodic waviness was introduced to a portion of the wall to investigate its effect on shock wave turbulent boundary layer interaction. The geometry of wall waviness was characterized by amplitude and number of cycles. Different cases were studied by varying the amplitude of waviness. The presence of wall waviness affected shock structure and flow separation patterns. Variations of flow properties with respect to waviness amplitude were also studied. [ABSTRACT FROM AUTHOR]

This study presents the transient nature and performance of viscous micropump for low Reynolds number where flow is assumed laminar, unsteady, incompressible and two dimensional. The device consists of a cylinder placed eccentrically inside an extremely narrow channel, where channel axis is perpendicular to cylinder axis. When the cylinder rotates, it generates a net force on fluid due to unequal shear stresses on the top and bottom surfaces of the cylinder. This net force is capable of generating a net flow against a pressure gradient. The flow field inside the micro channel has been analyzed by using structured grid Finite Volume Method (FVM) based on Navier-Stokes equation. All parameters used in flow simulation are expressed in non-dimensional quantities for better understanding of flow behavior, regardless of dimensions or the fluid that is used. The effect of the channel height (S), the cylinder eccentricity (ε), the Reynolds number (Re) and Pump load (P*) have been studied. Various flow patterns inside the micro pump as well as variations in flow velocity with time are obtained. Both the steady state and transient results of viscous micro pump are validated. It is found that the average velocity of fluid increases with increasing cylinder eccentricity and decreases with increasing the channel height. [ABSTRACT FROM AUTHOR]

Transonic flow past a supercritical airfoil is strongly influenced by the interaction of shock wave with boundary layer. This interaction induces unsteady self-sustaining shock wave oscillation, flow instability, drag rise and buffet onset which limit the flight envelop. In the present study, a computational analysis has been carried out to investigate the flow past a supercritical RAE2822 airfoil in transonic speeds. To control the shock wave oscillation, a cavity is introduced on the airfoil surface where shock wave oscillates. Different geometric configurations have been investigated for finding optimum cavity geometry and dimension. Unsteady Reynolds averaged Navier-Stokes equations (RANS) are computed at Mach 0.729 with an angle of attack of 5°. Computed results are well validated with the available experimental data in case of baseline airfoil. However, in case of airfoil with control cavity; it has been observed that the introduction of cavity completely suppresses the unsteady shock wave oscillation. Further, significant drag reduction and successive improvement of aerodynamic performance have been observed in airfoil with shock control cavity. [ABSTRACT FROM AUTHOR]

A numerical computation of an oblique shock wave incident on a turbulent boundary layer was performed for free stream flow of air at M∞ = 2.0 and Re1= 10.5×106 m-1. The oblique shock wave was generated from a 8° wedge. Reynolds averaged Navier-Stokes (RANS) simulation with k-ω SST turbulence model was first utilized for two dimensional (2D) steady case. The results were compared with the experiment at the same flow conditions. Further, to capture the unsteadiness, a 2D Large Eddy Simulation (LES) with sub-grid scale model WMLES was performed which showed the unsteady effects. The frequency of the shock oscillation was computed and was found to be comparable with that of experimental measurement. [ABSTRACT FROM AUTHOR]