The governing equations of a model of rotating generalized thermoelastic diffusion in an isotropic medium with temperature-dependent mechanical properties are formulated in context of Lord-Shulman theory of generalized thermoelasticity. The modulus of elasticity is taken as a linear function of reference temperature. The solution of the governing equations indicates the existence of four coupled plane waves in x-z plane. The reflection of plane waves from the free surface of a rotating temperature-dependent thermoelastic solid half-space with diffusion is considered. The required boundary conditions are satisfied by the appropriate potentials for incident and reflected waves in the half-space to obtain a system of four non-homogeneous equations in the reflection coefficients. The expressions for energy ratios of the reflected waves are also obtained. The reflection coefficients and energy ratios are found to depend upon the angle of incidence, reference temperature, thermodiffusion and rotation parameters. Aluminum material is modeled as the half-space to compute the absolute values of the reflection coefficients and the energy ratios. Effects of temperature dependence and rotation parameters on the reflection coefficients and energy ratios are shown graphically for a certain range of the angle of incidence of the incident plane wave.

The flow structure in the shear layer and in the recirculation zone of a skimming flow downstream of a vertical drop without end-sill measured using high speed particle image velocimetry (HSPIV) and flow visualization method is presented. The interface between the sliding jet and the recirculation zone (zone below sliding jet) was enhanced through non-ventilation condition between the drop structure and the jet. The flow field measured through HSPIV was used to represent the characteristics of mean streamwise velocity in the shear layer and mean horizontal velocity in the recirculation zone. With the growth of shear layer as the jet slides down over the recirculation zone, the momentum exchange from the sliding jet into the recirculation zone via the shear layer increases along with energy loss. Hence, it was observed that the amount of energy dissipated in the skimming flow at the drop structure without ventilation is greater than that with ventilation by an average value of 50% for Yc / H ≥ 0.2 (where Yc = critical depth and H = drop height). However, the flow structure in the recirculation zone is found to be analogous to that of turbulent plane wall jet. The nonlinear regression analysis is used to fit the regressed velocity profiles to the measured HSPIV mean velocity distributions. Further, the appropriate characteristic velocity and length scales are selected to attain the unique similarity profiles both in the shear layer and in the recirculation zone of the skimming flow. The selection of the characteristic scales is also discussed. The similarity profiles are well comparable with those of napped flow without end-sill and with ventilation as well as of skimming flow with end-sill and without ventilation. It is interesting to observe that, the proposed similarity profiles for the shear layer also map the data of backward-facing step flow and cavity shear flow. In addition, the turbulence characteristics in the shear layer, including turbulence intensities, turbulent kinetic energy, viscous and Reynolds shear stresses, and turbulence energy-budget balance, are illustrated in detail. From the variation of turbulence production it is observed that near the drop structure the energy exchange is from the chaotic recirculation zone to the sliding-jet flow, while in the later part it is reversed. Furthermore, the analysis of turbulence energy-budget balance indicates very significant role of turbulence production, pressure diffusion and turbulence diffusion as compared with turbulence advection that has very minor role in turbulence energy-budget balance for the central part of the shear layer.

In this paper, the numerical study of compressible flow around an airfoil is presented. The flow is analyzed in steady state for subsonic, transonic and even in the supersonic regimes at different angles of attack. In finite-volume method convective fluxes are calculated and compared by two schemes. Modified Jameson flux scheme based on flux averaging with pressure correction is used. Modified Roe scheme which is one of the characteristics-based schemes, with modification in calculation of Jacobian matrix based on Mach number is implemented. Second-order accuracy is used with artificial dissipation to overcome numerical oscillations. The fifth-order Runge–Kutta scheme is used for time discretization. A proper boundary condition based on characteristics is applied. Numerical experiments are performed on the NACA 0012 and also NACA 4412 airfoils. The results confirm the superiority of modified upwind Roe scheme regarding the accuracy, stability and convergence. Results are compared to available results in literature and a good agreement is noticed.

Human aortic valve is made of thin collagen type tissue. The three leaflets open and close under fluid forces exerted upon them. To simulate the hemodynamic characteristics of the blood flow, ANSYS CFX10.0 software was utilized to analyze the three-dimensional Reynolds-averaged Navier-Stokes equations. With a quasi-steady analysis model, we predict values of the blood velocity and the wall shear stress both over the valve leaflets and the endothelial lining. In addition, investigation on fluid dynamic of a heart valve supposed suffering prolapsed disease has been also conducted, and compared with normal valve. Analysis results highlight that leaflet opening situation and valve geometry affect the shear stress distribution and vortex flow regime. Maximum shear stress takes place near the center of leaflet trailing edge at the very beginning of systolic phase with value of 7.093N/m2. At peak systole, the maximum wall shear stress distributes near the aortic root where jet impingement takes place. Current study also demonstrated the interactive impact between low and high wall shear stress on relation to heart valve disease.

The clinical urination assist measures are usually taken to overcome the neurogenic bladder difficult to cure, but easily cause patients bladder stones, urinary system infection and other complications. To solve the problem of the urination assist of neurogenic bladder, a bladder power pump (BPP) driven by external electromagnet was proposed in this study according to the structure and micturition mechanism of human urinary bladder. The mathematic models of the BPP were established based on the theories of electromagnetics and fluid dynamics. A simulated experiment system with a bladder physical model for simulating human urinary system was designed according to the similarity criterion of fluid dynamincs. The micturition performance of the BPP was investigated by simulation and experiment. The results showed that the intravesical pressure and urine flow rate of the bladder physical model can be controlled by adjusting electromagnet exciting current. The micturition performance of the BPP is basically accordant with that of human urinary bladder detrusor. The established mathematic models are simple and practicable, which can provide the theoretical guidance for the performance analysis and structural optimization design of the BPP.

An annular elastic layer bonded between rigid plates and subjected to a compressive force normal to the layer is analyzed through a theoretical approach. On the basis of two kinematic assumptions, the governing equation for the mean pressure is established from the equilibrium equation, which is then solved by satisfying the stress boundary conditions. Through the obtained pressure expression, the compression stiffness of the bonded annular layer is derived in closed form and is very close to the finite element solution. The derived formula has no limitation on the Poisson's ratio and is more concise than the previous research. Through the asymptotic approach, the compression stiffness for the incompressible elastic layers is derived and is more accurate than the previous research obtained by directly neglecting the bulk compressibility. The stiffness reduction caused by the central hole is more prominent when the Poisson's ratio is close to 0.5.

Chang explicit method (2007) has been shown to be unconditionally stable for a linear elastic system and any instantaneous stiffness softening system while it is only conditionally stable for any instantaneous stiffness hardening system. Its coefficients of the difference equation for displacement increment are functions of initial tangent stiffness. Since Chang explicit method is unconditionally stable for a linear elastic system and any instantaneous stiffness softening system, its stability range can be enlarged if the initial tangent stiffness is enlarged by an amplification factor and then this amplified initial tangent stiffness is used to determine the coefficients. The detailed implementation of this scheme for Chang explicit method is presented and the feasibility of this scheme is verified.

This paper is concerned with the effects of column size, carbon fiber-reinforced plastics (CFRP) volumetric ratio, column side to corner radius ratio and column side aspect ratio on the confinement efficiency of rectangular concrete columns confined with CFRP. The confined concrete nonlinear constitutive relationships are adopted which account for concrete under unequal lateral confining stresses under multiaxial stress conditions. A stiffness reduction procedure upon concrete cracking or crushing is also proposed. The finite element model is initially confirmed by comparing its numerical solutions with the experimental results for various parameters. The effects of above parameters on the peak strength and ultimate strain of the confined concrete are then parametrically studied. The test results and results of the parametric study indicate that the column axial compressive strength and ultimate strain increase with CFRP volumetric ratio, but decrease as the column side to corner radius ratio or the column side aspect ratio increases. For columns of a particular corner radius and CFRP volumetric ratio, the column axial compressive strength and ultimate strain decrease as column size and column side to corner radius ratio increases.

This paper presents the optimal design of an electromagnetic vibration-based generator using the simulated annealing method (SA). To optimally extract the vibrational energy of a system vibrating at a specific frequency, the selected mass and spring stiffness of a resonant vibration is required. The relationship between induced energy and the generator's structure, its permanent magnet height and diameter, number of turns, and wire diameter in a single air coil are discussed. Also, a prototype of the vibrationbased electrical generator is built and tested via a shaker excited at resonance frequency and input amplitude of 0.06mm. Consequently, results reveal that the design parameters (permanent magnet height and diameter, number of turns, and wire diameter) play essential roles in maximizing electrical power.

This article aims to study numerically three-dimensional (3D) reactive turbulent flow in a combustion chamber of a gas turbine by solving a steady Reynolds-Averaged Navier-Stokes (RANS) )and energy equations. The Reynolds stress model (RSM) is coupled with the probability density function (PDF), laminar flamelet and Chemistry models to describe the turbulent flow and turbulence–chemistry interaction. Numerical computations are conducted to exhibit thermal and concentration behaviour under a quite number of factors, which influence the combustion process. Their influence are examined and compared favourably with available experimental results. Concentration of some radicals as O and OH are obtained assuming the partial-equilibrium assumption and using a PDF in terms of temperature. The 3D simulations demonstrate that the use of RSM, PDF and flamelet model allow simulating velocity and thermochemical fields.

This research takes the resistance formula of spherical cavity expansion theory as its foundation. It establishes a predictive model of the residual velocity, ballistic limit velocity, and penetration depth of ogival nose projectiles striking metal target plates at high speed. They are aimed at 6061-T651 aluminum plates of different thicknesses using the iterative algorithm of the numerical method, thereby investigating the theoretical calculation of the residual velocity, penetration depth, ballistic limit velocity, and changes in resistance of ogival nose projectiles when making a normal impact target. In addition to analyzing the resistance undergone by the projectile nose section, this predictive model also considers the effects of friction resistance of the projectile shank section. In this research, we also used the finite element software LS-DYNA to perform a simulated analysis on the penetration depth of the aluminum plate after normal perforation by ogival nose projectiles. Ballistic test experiments were then performed using 0.30” AP (armor piercing) bullets. Finally, a comparative analysis was performed based on the theoretical model, experiments, and numerical simulation results.

In this paper, a model has been presented for generating a special ring vortex by applying a nonconservative force with specific distribution through the Navier-Stokes equations. Moreover, the ring's vortical pattern has been compared with the analytical and experimental results. In continuation, the diffusion, dissipation, and dispersion errors of four basic convection term interpolation schemes for the velocity and vorticity field of the vortex ring have been investigated. The simulations are performed for both the small and large time steps. Next, an appropriate discretization scheme for the convection term, and a proper order of time steps for simulating flows that contain ring vortices have been proposed. Finally, the ring vortexes generated by non-conservative force are added to the turbulent channel flow as a bubble induced vortex on carrier flow in two-phase flows, and the drag reduction due to the interaction between ring vortexes and flow vorticity field is observed.