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The existence of a reverse von Karman street behind a flapping airfoil has been identified previously. The present paper numerically investigates the path through which the reverse von Karman street is established. The investigations are performed over a custom-designed airfoil performing combined motion of pitch and heave. The wake transformation path is established by increasing the flapping frequency and amplitude while visualizing the structure of the wake. The wake structure behind the flapping airfoil is identified using contours of vorticity, and the structures are arranged categorically. The force coefficients at different flapping frequencies and amplitudes are computed, and their influence on propulsion performance is assessed. The variation in wake structure behind the flapping airfoil appears to influence the force experienced by the airfoil significantly. The transition of the wake from periodic dynamics to aperiodic dynamics reduced the propulsion efficiency of the airfoil. [ABSTRACT FROM AUTHOR]

The conjugate heat transfer due to oblique impingement of two-dimensional, steady state, incompressible, turbulent slot jet on a uniformly heated flat plate has been studied in the present work. The standard high Reynolds number two-equation k − ε eddy viscosity model has been used for numerical simulation. The Reynolds number based on the hydraulic diameter of nozzle exit and turbulent intensity maintained at 9, 900 and 2% respectively. The angle of inclination 30◦, 45◦, 60◦ and, 75◦ degrees are considered for the numerical study. A uniform temperature higher than the jet exit temperature is provided to the bottom surface of the plate. The flow field have been studied using the contour plots of pressure and velocity in the fluid domain. The influence of inclination on the distribution of the local Nusselt number over the surface of impingement have been presented. It is found that the angle of impingement influences the flow field and heat transfer characteristics more in the downhill direction of the stagnation zone compared to the uphill direction. [ABSTRACT FROM AUTHOR]