In the present study, a 3-dimensional model was developed to investigate fluid flow in MHD micro-pumps. Initially, 3D governing equations were derived and numerically solved using the finite volume method/SIMPLE algorithm. The case study was a (MHD) micropump built in the year 2000 (channel length: 20mm, channel width: 800μm, channel height: 380μm and electrode length: 4mm). The applied magnetic flux density was 13mT and the electric current was different for various solutions (10 ~ 140mA). The numerical results were verified by experimental and analytical data for several solutions. In addition effects of magnetic field strength, electric current, geometrical parameters of the MHD micropump, electrode length and electrode location on its performance have been investigated. Finally the results has been considered and discussed.

The 3(UPS)-S fully spherical parallel manipulator is the most famous fully spherical parallel manipulator (FSPM). In this paper, we propose a novel approach to model the forward displacement analysis of the manipulator to obtain its assembly modes. Rodrigues’ formula is used as a mathematical tool to perform the proposed modeling. Utilizing geometry of the manipulator, two coupled trigonometric equations are obtained. Using Bezout's elimination method, the two coupled equations are transformed to one polynomial of degree eight. Finally, an example is given with eight real solutions. Therefore, the degree of the polynomial is minimal and the introduced modeling method is optimal. This is very important to control modelling and dynamics simulation. Also, the proposed method can be extended to the other FSPMs (e.g., 3(RPSP)-S, 3(RPSP)-S and 3(RSS)-S).

This work investigates mainly the double dispersion on the double diffusive convective boundary layer between a vertical plate immersed into a non-Darcy saturated porous medium with a nanofluid. The similarity transformations are involved and the governing system of nonlinear partial differential equations is converted into a set of nonlinear ordinary differential equations. Results are displayed graphically to illustrate the influence of δ, and ξ on the velocity, the temperature and concentration of the species profiles. Two interesting cases are treated, isothermal and non-isothermal wall plate. For a nanofluid, the rate of mass transfer is affected strongly by the double dispersion while the rate of heat transfer coefficient is less sensitive to it.

Geometric model of a lobed mixing exhaust system is created and its flow field is simulated by using the steady Reynolds Averaged Navier-Stokes (RANS) equations under the condition of different core flow inlet swirl angles. According to the numerical simulation results, due to the guidance effect of the lobe parallel side wall, the structure and vorticity of streamwise vortices change little near the lobe exit with inlet swirl angle, and it is the same with the thermal mixing efficiency. As the flow develops, although the inlet swirl angle has limited influence on the streamwise vorticity, it greatly affects the structure of streamwise vortices. It causes the thermal mixing efficiency to increase with the swirl angle. As for the total pressure recovery coefficient, it falls slightly when the inlet swirl strengthens. At the nozzle exit, the total pressure recovery coefficient of CFISA = 30° model is 0.5% lower than CFISA = 0° model. Moreover, as the inlet swirl strengthens, the thrust fall of lobed mixing exhaust system gradually accelerates, especially when the inlet swirl angle is over 15°.

This survey examines the geometrically nonlinear bending of a doubly clamped nanobeam that is subjected to combined actions of actuator voltage, prestress, and intermolecular force, with the pull-in instability as the primary objective. A nonlocal Euler-Bernoulli beam model, which takes the small scale effect into account, is developed making use of the principle of virtual displacement on the basis of Eringen's nonlocal theory in conjunction with von Kármán assumption. Due to complexity of the resulting equations, a shooting technique is established through taking the applied voltage as an unknown and the central deflection as a control parameter. This treatment has the capability of tackling the nonlinearities from both the large deformation and electrostatic force as well as the intermolecular force and enables the size dependent deflection response to an applied voltage of the nanobeam to be obtained conveniently. Validation is conducted in numerical examples through direct comparisons with existing solutions to confirm the proposed method. Parametric studies are undertaken addressing the impacts of the nonlocal effect, intermolecular force, residual stress, and geometry of the beam on the pull-in behaviors.

The unsteady magnetohydrodynamic free convective flow due to an oscillating porous flat plate in a rotating frame of reference are studied when thermal radiation and Hall currents are taken into consideration. The entire system rotates with a uniform angular velocity about an axis normal to the plate. A uniform magnetic field is applied along the normal to the plate directed into the fluid region. Copper, alumina and titania water nanofluids are considered. The governing equations are solved analytically by employing the small perturbation approximation. The numerical results for fluid velocity and temperature are presented graphically for the pertinent parameters and discussed in details.

This paper is former part of serial studies to investigate the influence of design parameters of tapered-spool type restrictors on static characteristics of hydrostatic bearing. The flow rates passing restrictors can determine the static characteristics of hydrostatic bearings. In this part an analytical method which includes formulas and solving is utilized to simulate dimensionless flow rate in both single-action and double-action tapered-spool restrictors. The numerical results illustrate the variations of flow rates with respect to the change of pressure and pressure difference, respectively. The findings give that the design parameters of tapered-spool restrictors and the useful range of recess pressure. The following part will depend on this paper results to study load capacity and static stiffness of hydrostatic bearing compensated by tapered-spool restrictor.

In the paper, the influence of shape memory alloy (SMA) by varying the parameters such as volume fraction, orientation, and temperature on the hybrid-SMA composite laminate subjected to low-velocity impact is studied. A theoretical model for the composite laminated plate bonded with SMA reinforced layers is presented. The constitutive relation of the SMA layer is obtained by using the method of micromechanics. The governing relations obtained can be used for theoretical predications of thermomechanical properties of SMA plies in this paper. The analytical expressions for the hybrid SMA composite plate are derived based on Tanaka's constitutive equation and linear phase transformation kinetics presented by Liang and Rogers.

The laminated plate theory, first-order shear deformation theory and minimal potential energy principle is utilized to solve the governing equations of the hybrid composite plate and calculate the absorbed energies including tensile, shear and bending.

An orthogonal array and analysis of variance is employed to investigate the influence of the mentioned parameters on the energy absorption of the hybrid laminated plate. The results showed that the effects of the phase transformation temperature are more significant than the effects of the volume fraction and orientation of SMA on structural energy absorption.

This paper deals with entropy generation of two immiscible fluids inside an inclined channel under the influence of a uniform magnetic field. The channel consists of two regions such that a viscous fluid occupies the region I and an electrically conducting fluid occupies the region II. The governing equations of momentum and energy for two regions are solved by Mathematica package BVPh 2.0 which is based on homotopy analysis method. The analytical results are validated against other numerical simulations and experimental data and excellent agreements are achieved. The entropy generation components due to heat transfer and fluid friction for two immiscible fluids are formulated and then the total entropy generation is computed. The influence of various parameters including Grashof number, Hartmann number and inclination angle on the total entropy generation and its components is examined and discussed. Results show that total entropy generation has a direct relationship with Grashof number and inclination angle, while it has a reverse relationship with Hartmann number. It can also be found that although the enlargement of Hartmann number increases the contribution of entropy generation due to Ohmic dissipation, it still reduces the total entropy generation inside the channel.

Cavitation bubbles, which always exist in the diesel jet leaving the nozzle and in diesel droplets breaking up from the jet as a result of supercavitation of the diesel within the injection nozzle, increase the instability of jet and droplets in part due to the two-phase mixture, while the mechanism of this effect is still unclear. Cavitation bubble expansion within the diesel droplet has been simulated numerically based on the volume of fluid (VOF) method, and the control mechanism of bubble growth process is analyzed by Rayleigh-Plesset equation. The process of bubble growth is divided into three parts, including surface tension controlled domain, comprehensive competition controlled domain and inertial force controlled domain. During the first stage, cavitation bubble growth is controlled by the surface tension, and the decrease of the surface tension leads to the increase of the bubble growth rate. During the second stage, the bubble growth rate is controlled by the comprehensive competition of the surface tension, the inertial force and the viscous force. During the third stage, the process of bubble growth is majorly controlled by the inertial force.

The purpose of this paper is to study the flow field of the combustion chamber in a simulated rotary engine by using a computational approach. A dynamic mesh technique is employed to overcome the moving and shape varying computational domain inside the combustion chambers as the rotor is spinning. The key parameters include spark plug timing, leading side spark plug location and intake port location, which are used to investigate their influences on flow field and combustion performance of a rotary engine. It was discovered, with a dual spark plug configuration, that better flame propagation could be obtained through the change of ignition timing. In addition, to change the leading side spark plug location, it was also found that combustion efficiency is improved by shortening the distance from the top dead center (TDC) center line, which is consistent with available experimental results. This research also discovered that the intake port should be properly located in order to prevent pressure loss in the combustion chamber during the compression stroke.

In this paper three-dimensional hyperbolic heat conduction equation in a cubic media with rectangular cross-section under a pulsed heat flux on the upper side has been solved analytically using the method of separation of variables and the Duhamel integral. The closed form solution of both Fourier and non-Fourier profiles are introduced with both modes of steady and pulsed fluxes. The results show the considerable difference between the Fourier and Non-Fourier temperature profiles. Then the answer procedure is used for modeling of interaction of a cubical tissue under a short laser pulse heating. The effects of pulse duration and laser intensity are studied analytically. Furthermore the results can be applied as a verification branch for other numerical solutions or laser treatments of biological tissues.

Effects of air injection on a centrifugal compressor performance are studied numerically and results are presented in this paper. Flow field is simulated based on solution of the Reynolds-Averaged Navier-Stokes equations utilizing the well-known k-ε turbulence modeling. To find optimum arrangement of the air injectors, including their numbers, positions and setting angles and also their mass flow rates, 10 different cases were proposed in this investigation. Results of velocity and pressure fields and streamlines patterns on various blade-to-blade and streamwise planes provided necessary data for analyses and discussions. These results revealed that a proper air tip injection can weaken the tip leakage flow strength and alleviate the blockages to the main stream near the casing. Hence, this technique can be used to extend the stable operating range of the compressor and delay the probable stall commencement. In addition, compressor can produce higher pressure ratios in cases of proper injections in comparison to no-injection case. Optimum injection configuration improved the stall margin of the proposed compressor by nearly 15.8%. Numerical results for no-injection case were compared with those of the authors own experimental works carried out on a proper test rig, which showed close agreement.

This study including two parts investigates the influence of design parameters of tapered-spool restrictors and hydrostatic planar bearing on static characteristics of load capacity and static stiffness. The former part provides guides for the design of single-action and double-action tapered-spool restrictors. This part provides design guides for planar hydrostatic bearing and for matching up with tapered-spool restrictor. The equations of flow continuity are utilized to determine the film thickness for open-type planar bearing and worktable displacement for closed-type planar bearing with respect to the recess pressure, respectively. The load capacity can be obtained by multiplying recess pressure by effective area of bearing pad. Furthermore, the static stiffness can be obtained by differentiating the recess pressure with respect to film thickness or worktable displacement. The finding results give that the usage range of recess pressure, and the availability ranges of design parameters of restrictor and bearing parameters. Which are found for getting the maximum stiffness.

Present paper addresses the numerical study of Sisko fluid model over stretching cylinder with variable thermal conductivity. The governing equations are simplified by incorporating the boundary layer approximations. After employing suitable similarity transformations partial differential equations are reduced to ordinary differential equations. To obtain numerical solution shooting method in conjunction with Runge-Kutta-Fehlberg method is used. For the analysis of model, variations due to different physical parameters involved in momentum and heat equations are reflected through graphs. Also, the effects of physical parameters on skin-friction coefficient and Nusselt number are represented through graphs as well as tables.

Deterministic Lateral Displacement (DLD) microfluidic devices provide a reliable label-free separation method for detection of circulating tumor cells (CTCs) in blood samples based on their biophysical properties. In this paper, we proposed an effective design of the DLD microfluidic device for the CTC separation in the blood stream. A typical DLD array is designed and numerical simulations are performed to separate the CTC and leukocyte (white blood cells) in different fluid flow conditions. Fluid-Solid Interaction method is used to investigate the behaviour of these deformable cells in fluid flow. In this study, the effects of critical parameters affecting cell separation in the DLD microfluidic devices (e.g. flow condition, cell deformability, and stress) have been investigated. The obtained results show that unlike leukocytes, the CTC’s motion is independent of the flow condition and is laterally displaced even in higher Reynolds number. Larger cells (CTCs) cannot intercept the low-velocity fluid near the wall of the posts; thus, they move faster and become separated from leukocytes. To reduce the cellular stress during separation process, which causes increase of cell viability and more effective design of microfluidic device, the results obtained here may be used as a significant design parameter for the DLD fabrication.

The results of a numerical simulation of heat and mass transfer during evaporation of a water droplet with solid inclusion in air at temperature as high as 1000K are presented. Typical heating steps of droplet until it reaches the conditions of intensive evaporation (i.e. the interface “solid inclusion – liquid” reaches the boiling temperature) are described. The roles played by the external air temperature and by the main properties of inclusion are detailed. The droplet size, the relation between the sizes of inclusion and a liquid layer during the heating up is determined. The necessary and sufficient conditions of intensive evaporation in the system “water droplet with solid inclusion in high-temperature air” are pointed out.

This paper presents experimental results on rapid freezing of water droplets injected into a low temperature environment. A heat balance method was applied to determine the ratio of the water droplets frozen at the collection after the airborne time. The experimental results show that rapid freezing of water droplets could be achieved within three seconds of airborne time. Droplet size distribution of the frozen water droplets after collection was estimated. Heat transfer during the airborne time was calculated with consideration of the droplet size distribution. At attempt was taken to compare the heat transfer obtained with some previous studies on heat transfer of spherical objects in air. The research results show that droplet size distribution is important for the prediction of heat transfer of water droplets traveling in air. The results presented in this study contribute to the understanding of heat transfer of water droplets injected into a low temperature air.

A theoretical study is presented for the problem of orthogonal axisymmetric stagnation flow towards an infinite horizontal plate with a constant velocity in the presence of viscous dissipation and heat generation. The governing equations are reduced to a system of nonlinear ordinary differential equations by means of appropriate transformations for the velocity components and temperature. The similarity equations are solved numerically using the Matlab routine bvp4c. The results are compared with those known from the literature and an excellent agreement is found. The effects of involved parameters on the x-wise velocity component, temperature, skin friction, heat transfer and entropy generation rate are presented in graphical and tabular forms. It was found that the Eckert number Ec, the Prandtl number Pr and the heat generation parameter α play a significant role on the temperature, heat transfer and entropy generation rate.

This study presents the influence of heat and mass transfer on peristaltic transport of Finitely Extensible Nonlinear Elastic Peterlin (FENE-P) fluid in the presence of chemical reaction. It is assumed that all the fluid properties, except the density are constant. The Boussinesq approximation which relates density change to temperature and concentration changes is used in formulating buoyancy force terms in the momentum equation. Moreover, we neglect viscous dissipation and include diffusion-thermal (Dufour) and thermal-diffusion (Soret) effects in the present analysis. By the consideration of such important aspects the flow equations become highly nonlinear and coupled. In order to make the problem tractable we have adopted widely used assumptions of long wave length and low Reynolds number. An exact solution of the simplified coupled linear equations for the temperature and concentration has been obtained whereas numerical solution is obtained for dimensionless stream function and pressure gradient. The effects of different parameters on velocity field, temperature and concentration fields and trapping phenomenon are highlighted through various graphs. Numerical integration has been performed to analyze pressure rise per wavelength.