In this paper, a thorough 2D unsteady computational fluid dynamic analysis was performed on a pitching airfoil to properly comprehend the dynamic stall and aerodynamic forces. The computational software ANSYS Fluent was used to solve the unsteady Reynolds-averaged Navier–Stokes equations. Low Reynolds number flows were modeled using the k-ω shear stress transport turbulence model. Aerodynamic forces, fluid flow structures, and flow separation delay angles were explored as a function of the Reynolds number, reduced frequency, oscillation amplitude, and mean angle of attack. The maximum aerodynamic forces, including lift, drag, and the onset of the dynamic stall, were all influenced by these variables. The critical parameters that influenced the optimum aerodynamic forces and ended up causing dynamic stall delay were oscillation amplitude and mean angle of attack. The stall angle was raised by 9° and 6°, respectively, and a large increment in the lift coefficient was also noted in both cases. Additionally, for the highest Reynolds number, a considerable rise in the maximum lift coefficient of 20% and a 28% drop in drag coefficient were observed, with a 1.5° delay in the stall angle. Furthermore, a significant increase of 33% in the lift force was seen with a rise of 4.5° in the stall angle in the case of reduced frequency.

The flow and heat transfer induced by an exponentially shrinking sheet with hybrid nanoparticles are investigated comprehensively in this paper. Nanoparticles are considered due to their unusual characteristics such as extraordinary thermal conductivity, which is significant in advanced nanotechnology, heat exchangers, material sciences, and electronics. The main objective of this research is to enhance heat transportation. The flow model is first transformed and simplified to a system of ordinary differential equations utilizing non-dimensional quantities and similarity functions. Then, the desired system is solved with the help of the Runge–Kutta numerical method and the shooting technique in MATLAB script. The results show that a stronger porosity parameter raises the temperature while diminishing the velocity. Additionally, they emphasize that augmentations in the magnetic parameter, Eckert number, radiation parameter, and the volume fractions of titanium dioxide and silver nanoparticles are all proportional to the temperature profile.

Turbocharged internal combustion engines offer efficient power-to-weight ratios, aiding in fuel-saving efforts within the automotive industry. However, when the flow is low, compressors show various instabilities, i.e., stall and inlet recirculation, which have a negative influence on their performance. This paper uses transient numerical simulations to explore the inlet recirculation phenomenon in a turbocharger compressor. The Reynolds-Averaged Navier–Stokes equations and k-ω SST turbulence model were solved using ANSYS CFX. The numerical model was verified using the experimental data for the design speed line. Analysis of mesh independence was performed to assess the discretization uncertainty near the design and surge line points. The results indicate that the inlet recirculation appears for moderate flows lower than design conditions. It shows significant radial and streamwise growth as the flow decreases. The reversed flow area increases more intensely in the radial direction at medium mass flow rates, whereas the streamwise growth is more substantial at low mass flow rates. The reversed flow reached 27% of the total inlet area at the point on the surge line. It was accompanied by a 15.7% drop in efficiency between the points with weak and strong inlet recirculation. The presented research indicates significant changes in the size of the inlet recirculation zone in the circumferential direction. It reaches its highest intensity close to the angular position of the volute tongue.

The operational stability and overall performance of turbocharger compressors are influenced by local as well as global instability phenomena under off-design conditions. This paper investigates the suppression of inlet recirculation and enhancement of surge operating range, using inlet fins. Both experiments and high-fidelity CFD simulations were used to assess the effect of fins on compressor performance, stability, and operating range. Experiments were conducted on a small turbocharger, while numerical simulations were performed using the RANS equations coupled with the k–ω SST turbulence model solved by ANSYS CFX. The numerical approach was validated, and a mesh independence study was conducted to evaluate discretization uncertainty at both design and off-design conditions. The results revealed that fins effectively suppressed upstream recirculation and preswirl, and promoted more uniform and directed flow into the impeller. Under stable, high-flow conditions, fins had a negligible influence on pressure ratio and efficiency. However, at low flow rates near surge, their presence significantly enhanced compressor performance. Pressure ratio increased by up to 5.4%, while the surge mass flow rate decreased by 8.4–10.4%, indicating a substantial extension of the stable operating range. Despite an efficiency penalty of up to 5% at low flow rates, the compressor performance at medium and high flow rates remains unaffected. The flow field analyses revealed that fins reduced swirl velocity, maintained higher incidence angles, and limited upstream momentum exchange, thereby stabilizing near-surge operation.

Oxytropis is a taxonomically challenging genus within the tribe Galegeae of the family Fabaceae. Despite its systematic importance, the seed morphology of Oxytropis has been poorly investigated. In the present study, we examined the seed morphology of 18 Oxytropis species representing 10 sections from the Pakistan, with the aim of evaluating the diagnostic value of seed traits using both light and scanning electron microscopy. The current investigation revealed two distinct seed shapes, namely cordiform and prolonged reniform, across the studied taxa. Seed length ranged from 1.75 mm in O. crassiuscula to 2.3 mm in O. duthieana, while seed width varied from 1.64 mm in O. mandokhailii to 2.13 mm in O. densa. Six distinct seed coat patterns were identified: microrugulate, rugulate, microreticulate, reticulate, lophate–reticulate and lophate–stellate. The observed seed morphological traits are largely consistent with those reported in previous studies and demonstrate potential taxonomic value. The results of PCA and UPGMA analyses suggest that seed traits can aid in clarifying species assemblages within Oxytropis and serve as a foundation for future systematic and phylogenetic studies.