Tidal and riverine flows are viable energy sources for consistent energy production. Installing and operating marine hydrokinetic (MHK) turbines requires assessing any potential impact of debris accumulation on turbine performance and sediment transport. More specifically, MHK devices may alter the natural sediment transport processes and cause debris accumulation, disrupting the natural sediment dynamic. In turn, these processes could affect the turbine’s performance. We carried out a series of large-eddy simulations coupled with bed morphodynamics, introducing various debris loads lodged on the upstream face of a utility-scale turbine tower. The objective is to systematically investigate the impact of debris accumulation on the performance and hydro-and morpho-dynamics interactions of the horizontal-axis MHK turbine under rigid and mobile bed conditions. To that end, we (1) employed the actuator line and surface methods for modeling turbine blades and the nacelle, respectively,(2) directly resolved individual logs, and (3) solved the Exner equation to obtain the instantaneous bed deformation of the mobile bed. Our analysis revealed that while the spinning rotor amplifies scour around the pile, debris accumulation modifies the sediment dynamics of the system. Also, it found that morphodynamic processes accelerate the wake recovery, slightly enhancing the turbine's performance.
We present a large-eddy simulation (LES) of saliva particle transport during normal human breathing through the nose and mouth. The flow of the air–saliva mixture is modeled using an Eulerian LES that is coupled with a Lagrangian particle tracking module to obtain trajectories of saliva particles in a room with stagnant air conditions. The coupled Eulerian–Lagrangian simulation yields novel insights into the intricate dynamics of Lagrangian coherent structures (LCS) and fundamental material lines that emerge from the saliva particles' trajectories during several breathing cycles. Further, we systematically compare the quantitative LCS diagnostics of mouth breathing with those of mouth and nose normal breathing. Analyzing the simulation results of human breathing from the mouth and nose, we show that, soon after the first breathing cycle, saliva particles form a series of roll-up vortex rings that propagate forward. The forward propagation of these vortex rings leads to the formation of an asymmetrical primary forefront vortex. The individual vortex rings continuously propagate forward, merging with the forefront vortex, and ascending along the limb of the leading vortex.
Pumping fluid is one of the crucial parts of any microfluidic system. Using electric and magnetic fields as a substitute for moving parts can have many advantages. In this study hydrodynamic and heat transfer characteristics of electroosmotic flow under influence of lateral electric and transverse magnetic field, are studied numerically. Results indicate that the dimensionless parameters such as Hartmann number, intensity of the lateral electric field, pressure gradient parameter and aspect ratio have an important role in controlling flow. It can be implied that the enhancement of pressure gradient leads to the decrease of critical Hartmann number, and this dependency can be reduced from 44% to 7% for S=0.5 to S=50 in two pressure gradients of Ω=1 and Ω=20. In addition, the reduction of aspect ratio of microchannel section leads to the increment of critical Hartmann number in a specified lateral electric field. At the end, thermal analysis is being done by consideration of the effects of magnetic and electric fields on the Nusselt number.
The mechanical properties of different polymer matrix composites are discussed in this research study. These composites are multiphase materials in which reinforcing elements and a polymer matrix are suitably combined. The mechanical properties of 18 PMCs, including nylon 66 reinforced with 5, 15, and 25% wt% silicon carbide (SiC) and nylon 66 reinforced with 5, 15, and 25% wt% boron carbide (B4C), were evaluated using an injection moulding technique at three different injection pressures in this study. The optimization of process parameters like reinforcement material, reinforcement quantity, and injection pressure to maximize the tensile and impact strength of nylon 66 composites are the main focus of this study. It is observed that the specimens 25% SiC with an injection pressure of 90 MPa has optimised tensile strength, while the specimen 5% B4C with an injection pressure of 90 MPa has optimised impact strength.
In this research study, the mechanical properties of several Polymer matrix composites are investigated. These composites are multi-phase materials in which reinforcing materials are properly mixed with a polymer matrix. More precisely, Nylon 6 reinforced with 5, 15 and 25 wt. % of silicon carbide (SiC) and Nylon 6 reinforced with 5, 15 and 25 wt. % of boron carbide (B4C), prepared by means of an injection moulding process at three different injection pressures are considered. Specific attention is paid to the tensile and impact strength of these composites. The Taguchi technique is used to optimize the process parameters such as reinforcement material, its percentage and the injection pressure. It is observed that the specimens 5% SiC with 80 MPa injection pressure display a better tensile strength and similarly the specimen 5% B4C with 90 MPa injection pressure have a superior impact strength.
The use of nanotechnology in healthcare and medicine is crucial, particularly for nanocoatings. The therapeutic potential of nanocoatings on medical implants and devices is examined in this chapter. It goes into the ingredients, production processes, and health benefits of nanocoatings. Device functionality and biocompatibility can be enhanced by nanocoatings. They are essential in addressing healthcare issues including cardiovascular stents and orthopedic implants. Additionally, nanocoatings are used in medication delivery systems, tissue engineering, and wound healing. This chapter offers important knowledge on the medical applications of nanocoatings to experts and researchers. Nanotechnology has the potential to alter the medical industry, which would be advantageous for patients.
The wind tunnel experimental study has been carried out on a double delta wing of different geometrical configurations such as 80°/45°, 75°/45° and 70°/45° sweep angles given as Model I, Model II and Model III with various freestream velocities from 10 to 40 m/s with a step of 10 m/s in Hindustan Institute of Technology and Science, Chennai, Low Speed Wind tunnel (HITSLSWT). The experiment is conducted for the measurement of lift and drag forces using single component force balance. The investigation was done to look into the effects of changing the double delta wing's leading edge sweep angles. Three differentmodels have been tested at various angles of attack ranging from0° to +16° and 0° to −16° with 4° and four different freestream velocities based on the delta wing’s chord. It is observed that the influence of variation of leading edge sweep angles affects the performance of aerodynamic characteristics of themodel. The increase in angle in attack with increased velocity gives better aerodynamic performance. This paper provides good insight into the aerodynamic force measurement of double delta wing and the low-speed performance of the models.
The blunted nose cone with and without a sharp aerospike and an aerodisk of various diameters and lengths are investigated numerically in detail in the current study at a hypersonic Mach number of 10. The aerodisk diameter is described as d/D ratios such as 0.2, 0.4 and 0.6, and the length of the aerospike is represented as the L/D ratio of 1, 1.5 and 2. The main objective of the research is to examine the aerodynamic properties of blunt noses with and without aerodisks and aerospikes, as well as the influence of shock production over the model. The design of blunted nose cones with aerodisk was made up using CATIA and numerical investigation was performed on the ANSYS Fluent. The turbulence model of SST k-omega was considered for study. The current study revealed that shock patterns drastically varied nearer to the nose cone model at L/D ratio 2 and variation of drag reduction occurred due to the increase in d/D ratio and aerospike and also flow pattern over the model was clearly investigated.
This research article focuses on addressing the challenges associated with joining dissimilar metals through the application of solid-state welding techniques, specifically Friction Welding (FW). The study aims to develop optimal welding conditions, tools, and parameters for achieving a successful Aluminum–Steel (Al–Fe) butt joint. The resulting weld is extensively characterized through mechanical tests, microstructure analysis, and micro hardness measurements. Additionally, finite element analysis is conducted to simulate the behaviour of the prototype engine valve. The findings provide valuable insights into the feasibility and performance of friction welding for dissimilar metal joints, contributing to the further development and understanding of this welding technique.
The CuS@reduced graphene oxide (CuS/RGO) hybrid nanocomposite was synthesized by facile hydrothermal method and used as a photoelectrode material in photovoltaic applications. In the hydrothermal route, RGO is formed by the reduction of GO with simultaneous formation of CuS/RGO nanocomposites. The CuS/RGO nanocomposites was investigated using powder XRD, TEM, HR-TEM, Raman, XPS, DRS UV–Vis spectroscopy, Photoluminescence (PL) measurements. XRD and TEM results suggest that CuS crystalline with individual spherical like homogeneous nanoparticles sizes in the range of 45–35 nm, which is distributed throughout the RGO sheets. We further construct the flexible photoelectrodes by using CuS and RGO and studied the photovoltaic performance. Photovoltaic parameters, such as short-circuit photocurrent density, open circuit voltage, fill factor and conversion efficiency were found to be 16 mA/cm2 , 0.71 V, 70.1% and 7.81% respectively, for CuS/RGO photoelectrode. The improved photo conversion efficiency of CuS/RGO is due to enhancing the electronic injection ability and reducing the photogenerated charge recombination. These photovoltaic results indicate a simple methodology for the low cost and effortless synthesis of an alternative CuS/RGO photoelectrode in high performance photovoltaic devices.
Department Of Mathematics, National University Of Skills (nus), Tehran, Iran.
Police Academy, Egypt