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The evolution of the secondary vortex arrangement around a foil, performing heaving and pitching motion, is numerically examined for a range of phase offsets (90 ° ≤ ϕ ≤ 270°) and reduced frequency (0.32 ≤ S t c ≤ 0.56), at a Reynolds number of 8000. The wake is dominated by two distinct systems of secondary hairpin-like structures. The first vortex system is associated with an elliptic instability, prompted by the paired primary and secondary leading edge vortices (LEV), which remains persistent within the entire range of Stc. However, the growth of the second system is more closely associated with undulations of the primary LEV at S t c ≥ 0.40, which amplifies as it sheds downstream of the trailing edge. The characteristic presence of the first system is directly linked to the growth of the secondary LEV, formed due to the large-scale interactions under localized adverse pressure gradients. These features promote a streamwise flow compression in neighboring regions of the primary LEV. Subsequently, the stability of these wake arrangements is evaluated using dynamic mode decomposition technique, which identifies a neutrally stable state at the fundamental forcing frequency and its harmonics. However, an increase in the modulus of the first three modes, as Stc increases, coincides with stronger three-dimensionality in the wake. The fundamental mode characterizes the roller undulations, while subsequent modes reveal that the two systems of secondary hairpin-like structures are closely associated with the harmonics of forcing frequency. [ABSTRACT FROM AUTHOR]

This study evaluates how Reynolds-averaged Navier-Stokes (RANS) models perform in simulating the characteristics of mean three-dimensional perturbed flows in pipes with targeted wall-shapes. The principal objective of this investigation is to evaluate which of the well-established RANS models can best predict the flow response and recovery characteristics in perturbed pipes at moderate and high Reynolds numbers (1×104-1.58×105). First, the flow profiles at various axial locations are compared between simulations and experiments. This is followed by assessing the well-known mean pipeflow scaling relation in the far downstream region, where the flow obtains a fully-developed state. The consistency of computationally predicted results and their similarities with experiments suggested that the Standard k-ε model can accurately capture the pipeflow characteristics in response to introduced perturbation with smooth sinusoidal axial variations. [ABSTRACT FROM AUTHOR]

Focusing on the problems faced by blind people, this paper has come up with the technology solution for the assistance of blind people. The solution is based on the intelligent data transmission to the earphone of a person based on task associated. The solution consists of a jacket to detect the obstacles along with a wearable box with task priority switchs. The system helps in detection of the obstacle and its height, one-touch cab booking and support of relatives, Ambulance services, Police services, etc. in the case of emergency. Either wired and wireless headphones or speakers can be interfaced with the device (box) to get audio notifications. The various tasks are triggered using multiple switches. The system will use a definitive SOC (System on Chip) platform recognized as Rasp-Pi-Pi along with ultrasonic sensor HCSR04, Neo-6M GPS (Global Positioning System) module, and different switches. The system uses a 20,000 mAh lion battery for the power supply. The voice signals can be provided in more than fifty languages. A fall detection system is also discussed in this paper. This system will be beneficial not only for blind but also for care of old aged people. [ABSTRACT FROM AUTHOR]