This paper proposes a correction method to improve the accuracy of traditional blade element momentum theory (BEMT) in predicting the mechanical power and power coefficient of horizontal-axis wind turbine (HAWT) blade. In this paper, the traditional BEMT incorporated with the Viterna-Corrigan (VC) stall/stall-delay model is proposed to improve the accuracy of power-curve prediction, by which its applicability is thus enhanced. For verification of the proposed method, three distinct types of geometries of HAWT blades subjected to different operations are studied with outcomes compared with experimental data. Two different wind turbines developed by National Renewable Energy Laboratory (NREL) were tested at constant rotational speeds in a full-scale wind tunnel to acquire performance data. As a comparative platform, another wind turbine designed by BEMT for this study was also experimented in identical environment but at variable rotational speeds. As expected, the results clearly indicate that the power-curve prediction is effectively improved by the proposed method especially in the stall region when compared with experimental data. Indeed, this study shows that the improved BEMT is an ideal means to accurately predict the power-curve used for designing an optimal HAWT rotor.

This research targets investigation of the internal elastic field near the boundaries of 3D anisotropic bodies by the boundary element method (BEM). This analysis appears to be most important, especially for the interest in the internal solutions near corners or crack tips, where structural failure is most likely to occur. Although the BEM is very efficient for analyzing the problem, nearly singular integration will arise when the internal point of interest stays near the boundary. The present work is to show how the self-regularized boundary integral equation (BIE) can be applied to the interior analysis for 3D generally anisotropic bodies. So far, to the authors' best knowledge, no implementation work has been reported in the literature for successfully treating the near boundary solutions in 3D generally anisotropic solids. In the end, a few benchmark examples are presented to demonstrate the veracity of the present approach for the interior BEM analysis of 3D anisotropic elasticity.

This work examines the magnetohydrodynamic (MHD) flow of second grade fluid due to a stretching cylinder with viscous dissipation. Advance heat transfer technique namely the Newtonian heating is employed to explore the characteristics of heat transfer phenomenon in the presence of Joule heating. Mass transfer is discussed with the combination of both homogeneous and heterogeneous reactions. Diffusion coefficients of species A and B are considered of the same size. Heat production due to chemical reaction is assumed negligible. Appropriate transformations are employed to convert the nonlinear partial differential equations to the nonlinear ordinary differential equations. Convergent solutions of momentum, energy and concentration equations are developed. Characteristics of different involved parameters on the velocity and temperature fields are shown graphically. Numerical values of skin friction coefficient and Nusselt number are computed and analyzed. Higher values of homogeneous reaction parameter results in the reduction of concentration profile while opposite behavior is observed for heterogeneous reaction parameter.

Prior to integrated circuit (IC) packaging, die performance must be verified using probe cards to screen for defective products. With the decrease in IC line width, the dimensions of the pads used for performance verification and the spacing between adjacent pads have also decreased. However, when the pad pitch is reduced to less than 30 μm, commonly used probe cards will face manufacturing problems in miniaturization. To resolve probe card manufacturing problems caused by the miniaturization of IC components, the use of an anisotropic conductive film (ACF) in probe cards was proposed in this study. Theoretical calculations and experimental testing of this probe structure were conducted to demonstrate the feasibility of this concept.

In theoretical calculations, composite material and buckling theory were utilized to evaluate the buckling behavior of the ACF. In experimental testing, photolithography and electroplating techniques were used to control the line width and spacing intervals of the micron-scale metal wires in the ACF. After the ACF was fabricated, the mechanical properties of the ACF during wafer testing were assessed. Theoretical analyses and experimental testing verified that ACFs can potentially be applied to the performance verification of IC products. In the ACF structure, multiple probes came into contact with each pad. Therefore, ACFs can potentially be applied to the performance verification of IC components with pad diameters of less than 20 μm. The results of this study directly benefit the miniaturization of ICs.

The influence of temperature-dependent fluid properties on flow and heat transfer of an electrically conducting fluid over a stretching sheet with variable thickness in the presence of a transverse magnetic field is analyzed. Using similarity transformations, the governing coupled non-linear partial differential equations (momentum and energy equations) are transformed into a system of coupled non-linear ordinary differential equations and are solved numerically by Keller-box method. For increasing values of the wall thickness parameter, the analysis reveals quite interesting flow and heat transfer patterns. The effects of the temperature dependent viscosity, the wall velocity power index, the thermal conductivity, the wall temperature parameter and the Prandtl number on the flow and temperature fields are presented. The obtained numerical results are compared with the available results in the literature for some special cases and are found to be in excellent agreement. The skin friction and the wall temperature gradient are presented for different values of the physical parameters and the salient features are analyzed.

An exact analytical solution to the three-dimensional elasticity problem for a transversely-isotropic composite layer is constructed by making use of the direct integration method along with the Fourier double-integral transform. The original problem is reduced to a system of governing partial-differential equations for separate stress-tensor components. The governing equations are accompanied with corresponding local and integral boundary conditions, obtained on the basis of the original local boundary conditions imposing the normal and shearing forces on the limiting planes of the layer. The numerical analysis of the obtained solution is presented for certain transversely-isotropic composite materials.

A numerical simulation of the particle-gas flow in a vertical turbulent pipe flow was conducted. The main objective of the present article is to investigate the effects of dispersed phase (particles) on continuous phase (gas). In so doing, two general forms of Eulerian-Lagrangian approaches namely, one-way (when the fluid flow is not affected by the presence of the particles) and two-way (when the particles exert a feedback force on the fluid) couplings were used to describe the equations of motion of the two-phase flow. Gas-phase velocities which are within the order of magnitude as that of particles, volume fraction, and particle Stokes number were calculated and the results were subsequently compared with the available experimental data. The simulated results show that when the particles are added, the fluid velocity is attenuated. With an increase in particle volume fraction, particle mass loading and Stokes number, velocity attenuation also increases. Moreover, the results indicate that an increase in particle Stokes number reduces the special limited particle volume fraction, according to which one-way coupling method yields plausible results. The results have also indicated that the significance of particle fluid interaction is not merely a function of volume fraction and particle Stokes number.

Assumption that the common interfaces of the media are perfectly bonded may not be always true. Situation may arise that composition of the two medium may be responsible for weakening the contact between them. So, it becomes obligatory to consider a loosely bonded interface in such cases which may affect the propagation of elastic waves through them. This paper thrashes out the propagation of torsional surface wave in an initially stressed visco-elastic layer sandwiched between upper and lower initially stressed dry-sandy Gibson half-spaces, theoretically. Both the upper and lower dry-sandy Gibson half-spaces are considered to be loosely-bonded with the sandwiched layer. Mathematical model is proposed and solution in terms of Whittaker's and Bessel's function is obtained. Velocity equation is obtained in closed form, its real part deals with the dispersion phenomenon whereas its imaginary part provides the damping characteristics. Influence of heterogeneities, sandiness, gravity parameters, initial-stresses, loose-bonding and internal-friction on the phase and damped velocities of torsional wave are computed numerically and depicted graphically. Deduced dispersion equation and damped velocity equation matches with classical Love-wave equation and vanishes identically for the isotropic case respectively.

In the fields of engineering, nanoscience, and biomechanics, thin structural members, such as beams, plates, and shells, that are supported by an elastic medium are used in several applications. There is a possibility that these thin structures might buckle under severe loading conditions; higher-order, complicated elastic buckling modes can be found owing to the balance of rigidities between the thin members and elastic supports. In this study, we have shown a new and simple ‘power law’ relation between the critical buckling strain (or loads) and rigidity parameters in structural members supported by an elastic medium, which can be modelled as a Winkler foundation. The following structural members have been considered in this paper: i) a slender beam held by an outer elastic support under axial loading, ii) cylindrical shells supported by an inner elastic core under hydrostatic pressure (plane strain condition), and iii) complete spherical shells that are filled with an inner elastic medium.

The present study investigates the hydromagnetic pulsating nanofluid flow in a porous channel with thermal radiation. In this work, we considered water as the base fluid and silver (Ag), copper (Cu), alumina (Al2O3) and titanium dioxide (TiO2) as nanoparticles. The Maxwell-Garnetts and Brinkman models are used to evaluate the effective thermal conductivity and viscosity of the nanofluid. The governing equations are solved analytically and the influence of various parameters on velocity, temperature and heat transfer rate has been discussed through graphical results. From the results, it is found that the rate of heat transfer enhances with an increase of nanoparticle volume fraction. Further, the heat transfer rate is higher for silver nanoparticles as compared with copper, alumina and titanium dioxide.

Speaking is a very complex process resulting from the interaction between the air flow along the larynx and the vibrating structure of the vocal folds. Sulcus is a disease missing layers in the vocal folds result in cracks resulting in some disorders in producing sounds. Sulcus and its effects on the vocal cord vibrations are numerically studied for the first time in this paper. An ideal model of healthy vocal folds and Sulcus vocalis has been two-dimensionally defined and the finite element model of vocal folds is solved in a fully coupled form. The proposed calculative model was used in a fluid range of the computational fluid dynamics, arbitrary Lagrangian-Eulerian (ALE), incompressible continuity and Navier-Stokes equations and in a structure range of a three-layer elastic linear model. Self-excited oscillations were presented for vocal folds among type II patients and compared with healthy models. Responses were qualitatively and quantitatively studied. The healthy model was compared with numerical and empirical results. In addition, the effects of the disease on the flow parameters and the vibration frequency of the vocal folds were studied. According to the simulated model, the oscillation frequency decreased 25% and the average and instantaneous volume flux significantly increased compared to healthy samples. Results may help present a guideline for surgery and subsequently evaluate patients’ improvement.

This study investigated the flow bifurcations of flows driven by a pressure gradient in a rectangular curved tube. When fluid flows within a curved tube, due to the centrifugal effect, secondary vortices can be induced in the cross section of the tube. The secondary flow states are dependent on the magnitude of the pressure gradient (q) and the aspect ratio (γ). In this study, the continuation method was applied to investigate the flow bifurcations in a curved tube with increasing pressure gradient (1 < q < 6000) and aspect ratio (0.9 < γ < 1.4).

The bifurcation diagrams are composed of solution branches, which are linked by limiting points or bifurcation points. The flow states in a solution branch belong to the same group. The ranges of the flow states and the relationship between the states can also be derived from the bifurcation diagrams. In this study, two types of bifurcation were found, one in the range of 0.9 < γ < 1.17, and another in the range of 1.18 < γ < 1.4. The ranges of stable flow solutions and the distributions of limit and bifurcation points in both pressure gradient and aspect ratio are derived in this study.

In recent years, the material Au-20Sn eutectic solder, which is resistant to high temperatures, is used for electric interconnections in high-power modules, the material properties such as temperature and strain rate dependent stress-strain curve are critically needed for reliability assessment of Au-20Sn solder joint. Thus, this study was performed to determine the material properties of Au-20Sn eutectic solder under various strain rates and temperature loads. Many researches using shear test to determine the shear resistance of solder joint, however, the mechanical strength as measured by the shear test is the maximum shear strength of the package joint, but this measurement does not represent the stress-strain behavior of Au-20Sn material. To identify the material properties of Au-20Sn eutectic solder, the tensile test was performed to measure its mechanical strength and nonlinear material properties. The strain rate effect was examined in terms of the influence of the mechanical strength on the Au-20Sn eutectic solder at different tensile rates. The temperature-dependent material properties of Au-20Sn solder were also measured under various thermal loadings, and material properties of Au-20Sn obtained in this research can be applied to the simulation model, the thermomechanical behavior and reliability of the power module can be further analyzed and evaluated.

An investigation of unsteady MHD double diffusive natural convection flow of a viscous, incompressible, electrically conducting, heat absorbing, radiating and chemically-reactive fluid past an exponentially accelerated moving inclined plate in a fluid-saturated porous medium, when the temperature of the plate and the concentration at the surface of the plate have ramped profiles, is carried out. Exact solutions for the fluid velocity, fluid temperature and the species concentration, under Boussinesq approximation, are obtained in closed form by the Laplace transform technique. The expressions for the shear stress, rate of heat transfer and the rate of mass transfer at the plate are also derived. Numerical evaluations of the fluid velocity, fluid temperature and the species concentration are performed and displayed graphically whereas those of the shear stress, rate of heat transfer and the rate of mass transfer at the plate are presented in tabular form for various values of the pertinent flow parameters.

The purpose of this study is to highlight the effectiveness and necessity of the computational methods applications for architecture conceptual designs and improve the use of advanced simulation tools in urban planning. The results can provide the urban designers, planners and other decision makers with useful design information for assessing human wind comfort of the surrounding open spaces of public buildings in an urban area. Among different kinds of public buildings, museum architecture is of significant social value and importance for the augmentation of urban image. Using the Guggenheim Museum Bilbao for the case study, this investigation performed CFD simulations of the airflow over the museum to characterize the wind environments around the buildings. The predicted wind speed distributions were used to determine the wind comfort level of the featured spots around the museum for evaluating the suitability allowing visitors to sit or stand at the pedestrian plane for extended periods.

In this study, attention is focused on the numerical simulations of laminar fluid flow and heat transfer in straight smooth-walled parallelogram channels with various aspect ratios (α) and inclined angles (θ). The Reynolds number (Re), characterized by the channel hydraulic diameter and the working fluid of water, is fixed at 100. The examined α and θ range from 1 to 10 and 45° to 90°, respectively. Their effects on the thermal fluid features are explored under three thermal boundary conditions: constant wall temperature (TBC), constant axial heat transfer rate with constant peripheral temperature (H1BC), and constant wall heat flux (H2BC). The SIMPLE algorithm is employed for velocity–pressure coupling with the algebraic multigrid method, while the second-order upwind scheme is utilized for spatial discretization in pressure term; the momentum and energy equations are solved with a QUICK scheme; Least Squares Cell-Based Gradient Evaluation is applied for predicting scalar values at the cell faces and for computing secondary diffusion terms and velocity derivatives. One of the new findings is that there exists a critical value of θ = 70° below which the Nusselt number under H2BC increases with increasing α whereas beyond which the trend reverses, a result distinct from those computed with TBC and H1BC. Moreover, TBC is found to be a time-saving alternative to H1BC. Furthermore, both Nusselt numbers under the three thermal boundary conditions and friction factor times Re are successfully and compactly correlated with α and θ to offer useful reference for designing micro-cooling channels.

The effects of backward inclination angle on flow characteristics and jet dispersion properties of a stack-issued jet in crossflow were studied by means of instantaneous and long-exposure photography, particle image velocimetry (PIV), and tracer-gas concentration detections at a Reynolds number of 2,400, a jet-to-crossflow momentum flux ratio of 1.0, and the backward inclination angles θ = 0° - 60°. Three characteristic flow patterns featured by different near-wake flow structures were found within the surveyed span of the backward inclination angle: low (θ ≤ 25°), mediate (25° < θ < 50°), and high (θ ≥ 50°). In the range of low backward inclination angle, mushroom vortices appeared in the upwind shear layer. Jet fluids were entrained into the jet- and tube-wakes because the near wake region was characterized by a jet-wake vortex and a downwash flow. In the range of mediate backward inclination angle, forward-rolling vortices were formed in the upwind shear layer. Jet fluids were entrained into the jet wake but not appearing in the tube wake because the near wake was characterized by an isolated tube wake and up-going flows. In the range of high backward inclination angle, small-sized forward-rolling vortices were observed in the upwind shear layer. Jet fluids were not observed in both the jet- and tube-wakes because all flows went forward without reversal or vortex, which was similar to that in a jet in co-flow. Large turbulence intensities occurred around the jet-wake vortex and along sides of the tube wake bifurcation line, therefore the mixing at the low backward inclination angles presented better properties than those at mediate and high backward inclination angles owing to the featured flow structures and turbulence intensities.

In this work, we investigate electromagnetohydrodynamic (EMHD) flow of Powell-Eyring fluid through a slit confinement. The approximate analytical solution and numerical result of EMHD velocity are obtained by using homotopy perturbation method and Chebyshev spectral method, respectively. The analytical solutions are found to be in good agreement with numerical results under the same conditions. The influences of Hartmann number Ha, electrical field strength parameter S, the Powell-Eyring fluid parameters γ and β on velocity are discussed in detail. It is found that the volume flow rate of Newtonian fluid is always larger than that of Powell-Eyring fluid. The results reveal the intricate interaction between EMHD effect and fluid rheology involving non-Newtonian fluid. Therefore, the results are useful in dealing with some non-Newtonian biomicrofluidic systems.

In recent days, nanofluids have derived the attention of researchers, scientists and engineers due to their abundant applications in Engineering and technology and specific applications such as Electronics cooling, vehicle cooling, medical applications including cancer therapy and so on. Motivated by these applications of nanofluids, this work is mainly concerned with the convective heat transfer of nanofluids. MHD slip flow of nanofluids with heat absorption over a rotating disk subjected to suction has been analyzed. Two types of nanofluids such as copper-water nanofluid and silver-water nanofluid are considered for the present study. The system of axisymmetric nonlinear partial differential equations governing the hydromagnetic steady flow and heat transfer are reduced to nonlinear ordinary differential equations by introducing suitable similarity transformations. The resulting non-linear ordinary differential equations are solved numerically by most efficient Nachtsheim-Swigert shooting iteration technique for satisfaction of asymptotic boundary conditions along with Runge – Kutta Fehlberg Method. The flow field is affected by the presence of physical parameters, such as magnetic interaction parameter, suction parameter, slip parameter and solid volume fraction, whereas the temperature field is addionally affected by magnetic interaction parameter, suction parameter, internal heat absorption parameter and solid volume fraction. With the amplifying effect in magnetic interaction parameter, suction parameter, slip parameter and solid volume fraction, the radial and tangential velocities decline. Axial velocity gets decelerated for increasing magnetic interaction parameter and slip parameter whereas it gets accelerated for growing effect of suction parameter and solid volume fraction. The temperature of the fluid within the boundary layer enhances with the increasing effect of magnetic interaction parameter and solid volume fraction while it reduces for increasing values of the suction parameter and internal heat absorption parameter. Also the values of radial and tangential skin friction coefficients and Nusselt number are obtained numerically and are tabulated.

By introducing the concept of forming springback anti-coupled systems and considering the influence of the self damping effect, meanwhile establishing higher-order geometrical nonlinear equation of a high strength and low alloy (HSLA) steel plate, then a set of nonlinear dynamic springback governing equations of the plate are obtained. The finite difference method, Newmark method and iterative method are applied to solve the whole problem. Numerical results denote that the boundary conditions, thickness-length ratio of the plate and initial impact velocity of the impactor have great influence on the springback amount of the rectangular HSLA steel plate, besides the natural frequency is affected a lot by the boundary conditions and thickness-length ratio. The effect of higher-order geometrical nonlinearity on the springback amount of the plate can be ignored, considering the first-order geometrical nonlinearity is enough accurate for such similar nonlinear dynamic problems.