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In the past few decades, the permanent magnetic flux switching machines has aroused the interest of researchers in various fields. However, it has been found that the salient rotor design results in a longer magnetic flux path between the stator and the rotor, causing poor magnetic coupling and low torque. This research proposes a permanent magnetic flux switching motor with non-overlapping modular rotor windings. The magnetic flux path of the proposed modular rotor is significantly shorter, resulting in higher torque, and no overlap reduces copper loss and motor weight. Both the salient and modular rotor PMFSM are designed using JMAG Designer software version 14.1. Since the magnetic flux flows between the two stator teeth and a section of the modular rotor is relatively short, the magnetic flux of the modular rotor design is greater than the magnetic flux of the salient rotor design. The torque and power provided by the PMFSM modular rotor are much higher than the salient rotor, 58.24 Nm and 22.76 W, respectively. Finally, proposed modular rotor PMFSM, generates higher magnetic flux to improve torque and power. [ABSTRACT FROM AUTHOR]

In this paper, an effort is made to analyses the effect caused due to viscosity variation on a slider bearing having an exponential film profile. The impact caused by magnetic field on such a system consisting of an electrically conducting non-Newtonian fluid is considered. Expression for flux of the flow is derived. Analysis for the impact of viscosity variation and MHD on the volume of fluid discharged is plotted. [ABSTRACT FROM AUTHOR]

Improvements on suspension systems has been the eye of researchers past few decades as semiactive and active suspension systems put forth a new level of possibility for varied damping force providing a better stability to the system. Magnetorheological (MR) suspensions provide an effective replacement for passive suspension due to controllable damping force and its cost effectiveness when compared to active suspension. Different damper designs provide variable damping force in MR dampers due to the variation in the magnetic flux depending on the piston core. This work compares with two different magnetorheological piston designs namely Axial and Radial, in design, flow of magnetic flux lines and its characteristics based on damping force, velocity and current. [ABSTRACT FROM AUTHOR]

The ocean plays a vital role in climate regulation. The purpose of this study was to determine the value of CO2 flux, determine the role of the seagrass ecosystem in Karimunjawa Island waters, and determine the factors that influence CO2 flux in Karimunjawa waters. This research was conducted in the western waters of the Karimunjawa Island seagrass ecosystem in August 2020 with survey and quantitative methods. Sampling was carried out at eight stations using the purposive sampling method. Physical, chemical and biological variables were measured, such as temperature, DO, salinity, phosphate, silicate and chlorophyll-a. The measurement of the carbonate system in this study was Total Alkalinity, DIC and pH. The partial pressure of CO2 in the oceans is calculated using the ocean pCO2 formula= 6.31T2+61.9Chl a2 – 365.85T - 94.41Chl a+5715.94 and the atmospheric CO2 partial pressure with the formula pCO2 atm=xCO2 atm (pb-H2O). Calculate CO2 flux using the formula: CO2 flux= Kh x kwa x (ΔpCO2). In general, the waters of the western Karimunjawa seagrass ecosystem act as CO2 releasers, the CO2 flux obtained from this study ranged from 15.60-26.36 mmol/m2/day. The flux flow is positive, where the CO2 flow moves from the ocean to the atmosphere. Based on PCA analysis, the CO2 flux has a close relationship with pCO2 water, with a correlation value of 0.884. [ABSTRACT FROM AUTHOR]

On the basis of the solution of a two-dimensional problem of thermal conductivity, the process of heat transfer in a plate made of composite materials is investigated by the finite element method. Linear triangular finite elements are used to solve the plane problem of heat conduction. With the developed algorithm and software, a numerical solution of specific problems is presented and the temperature field distribution is studied. The results obtained are compared with the analytical solution. Isotherms of temperature distribution in a nonhomogeneous plate with inclusions are given. The influence of concentrators on the formation of a nonhomogeneous temperature field is studied. It was found that with time, the heat flux flows around the inclusions since the thermal conductivity of the inclusion is less than the thermophysical parameters of the base material. The presence of inclusions reduces the rate of propagation of the heat flow. [ABSTRACT FROM AUTHOR]

In this paper we present the implementation of a stabilized finite element method (FEM) in the computational fluid dynamics code for numerical simulations of supersonic and hypersonic flows using the Flux Correction Transport (FCT), and the results of computational experiments. The instabilities observed in FEM numerical solutions for supersonic flows reflect the fundamental problems of the FEM, and cannot be avoided with any finite element approach modifications. The papers published for scalar transport, (Kuzmin 2009), and for compressible flow problem, (Kuzmin, Moller 2010) provided a break-through approach for this problem, resulting in algorithms of increased stability and performance, by implementing this on the level of the matrix of the algebraic linear system, resulting from PDE discretization in the FEM. The FEM with the FCT results in a stable algorithm for accurate simulation compressible flows, examples of simulations and comparisons are presented. An additional advantage of this approach is that simulations can be performed with a much larger time step, with the Courant-Friedrichs-Lewy (CFL) condition 1 or more (up to 20) and get numerically stable long time transient, and stationary solutions. This results in a significant speedup of simulations (up 30X) compared to maximum possible CFL=0.03 for methods without FCT. Apparently our FCT implementation FEM for supersonic flows was the first at a time successful implementation following the invention of FCT into FEM by (Kuzmin 2010). [ABSTRACT FROM AUTHOR]

The numerical simulation of shock waves in supersonic flows is challenging because of several instabilities which can affect the solution. Among them, the carbuncle phenomenon can introduce unphysical perturbations in captured shock waves. In the present work, an hybrid numerical flux is proposed for the evaluation of the convective fluxes that avoids carbuncle and keeps high-accuracy on shocks and boundary layers. In particular, the proposed flux is a combination between an upwind approximate Riemann solver and the Local Lax-Friedrichs scheme. A simple strategy to mix the two fluxes is proposed and tested in the framework of a discontinuous Galerkin discretisation. The approach is investigated on the supersonic flow around a cylinder, on the supersonic flow on a flat plate and on the flow in a rocket nozzle. [ABSTRACT FROM AUTHOR]

Development of the theory of rapid growth in terms of phase field model was provided for multi-grain case. The growth of polycrystalline multi-component alloying systems, which driving force regarded as the Gibbs free energy change on crystallization, was studied with the help of the model of fast phase transformations. The special attention was given to the specific rapid solidification features, affecting on the need of using both classical slow and fast variables. Finally, the evolution equations for diffusion flux and gradient flow were developed concerning multi-phase interpolation among growing poly-crystallites. In the limit of relaxation time of fast thermodynamic variables the model tends to restore the Moelan’s phase field model of anisotropic grain growth. [ABSTRACT FROM AUTHOR]

Coflow-jet (CFJ) airfoil is a new type of zero-net mass flux active flow control of the airfoils. The concept was proposed by Zha et al from Miami University and presents several extraordinary aerodynamic characteristics like: super lift coefficient, small or even negative drag coefficient and almost stall free behaviour. All these make the CFJ airfoils suitable for highly efficient airplanes including electric airplanes with distributed thrust. This paper presents an evaluation of the broadband aeroacoustic noise of a NACA 6415 CFJ airfoil and compares it with the basic NACA 6415. Numerical simulation for aerodynamic and aeroacoustic field using Navier –Stokes equations and aeroacoustic analogies are conducted with Ansys Fluent and Msc Actran solvers. [ABSTRACT FROM AUTHOR]

The paper considers isobaric vortex shear flow of a vertically swirled viscous incompressible fluid. The exact solution of the overdetermined system of Navier-Stokes equations for an incompressible fluid is computed. It is demonstrated that there are counterflows in the fluid when the Navier boundary condition is used to account for slippage. [ABSTRACT FROM AUTHOR]

We probe vortex dynamics in a thin film superconductor non-locally, i.e. away from the point where an electric current is applied. Lorentz force decreases along vortex motion and so does the vortex velocity. We also propose to perform voltage measurements concerning additive and cancelling flux flows at these non-local points. By analyzing minimal data that has been published previously we see that non-local flux dynamics is very different compared to usual flux dynamics with regions of decreasing resistance in increasing current. This point outs new dynamical aspects in vortex transport. Apart from this our studies are for those who wish to image slow vortices using scanning probe techniques. [ABSTRACT FROM AUTHOR]

The study shows advantages of high-order discontinuous Galerkin method in terms of accuracy for vortex flows. For this sake a test for 2D vortex evolution in non-viscid flow has been performed. It gives estimates of numerical scheme viscosity for different meshes and order of schemes. The main task to be solved is a generation of vortex past the wing at a small angle of attack, which is installed in wind tunnel. [ABSTRACT FROM AUTHOR]

The paper is devoted to the experimental study of the growth of mass flux pulsations and disturbances of total temperature at the laminar-turbulent transition process in a modulated swept-wing boundary layer at Mach number of the oncoming flow M = 2 and 2.5. Total temperature and mass flow pulsations were measured by a constant-temperature anemometer (CTA), operating in the scanning regime. It was found that at laminar-turbulent transition process the ratio of the mass flow and total temperature pulsations remains almost constant. [ABSTRACT FROM AUTHOR]

The use of delta wings is widely used for high-speed aircraft such as fighter aircraft. In the delta wing, there is a pressure difference that causes the vortex flow and forms a vortex core with a very low pressure that will lead to the addition of lift force. Increased angle of attack will raise the vortex core speed so that the force will also rise, but under certain conditions, the vortex core structure will be destroyed, or there is a vortex breakdown that will remove the lift force. The analysis of the occurrence of vortex breakdown becomes very important to maintain lift force on the wing. Vortex breakdown analysis can be done through visualization techniques. The use of water tunnel as a visualization test facility has been widely used and has advantages in detail visualization. This research will be testing the character of vortex breakdown on delta wing by using GAMA water tunnel facility. For comparison and validation would be used computational fluid dynamics (CFD) technique. The results of the research show that the GAMA water tunnel facility can show the vortex breakdown phenomenon and the aerodynamic forces that occur on the delta wing. These results have conformity with the test using CFD and other references where the vortex breakdown was affected by the angle of attack and the change of the sweep angle. [ABSTRACT FROM AUTHOR]

Nb2PdS5 is a novel superconductor having promising potential for applications. Synthesis of this by solid state reaction, characterization using susceptibility and resistivity of Ta substituted Nb2PdS5 is reported in the present paper. Nb1.75Ta0.25PdS5 shows a diamagnetic transition at 6K while the onset of superconducting transition in resistivity is found at 6.73K; the slight difference is attributed to Aslamazov-Larkin paraconductivity fluctuations. This can be ascertained from the fact that the transition seen in resistivity is so broad that the zero resistance state is elusive due to weak inter grain coupling. We also report temperature dependence of resistivity under magnetic fields up to 16T that shows considerable broadening in fields that can be attributed to the field induced resistive state with underlying vortex motion. The results are explained based on models like thermally activated flux flow (TAFF) in the light of Kramer’s relation. The normal state just above Tc has a negative temperature co-efficient of resistivity reminiscent of the Anderson localization scenario. The estimated critical field of 27T is more than two times higher than that of Pauli limit. [ABSTRACT FROM AUTHOR]

Nb2PdS5 is a novel superconductor having promising potential for applications. Synthesis of this by solid state reaction, characterization using susceptibility and resistivity of Ta substituted Nb2PdS5 is reported in the present paper. Nb1.75Ta0.25PdS5 shows a diamagnetic transition at 6K while the onset of superconducting transition in resistivity is found at 6.73K; the slight difference is attributed to Aslamazov-Larkin paraconductivity fluctuations. This can be ascertained from the fact that the transition seen in resistivity is so broad that the zero resistance state is elusive due to weak inter grain coupling. We also report temperature dependence of resistivity under magnetic fields up to 16T that shows considerable broadening in fields that can be attributed to the field induced resistive state with underlying vortex motion. The results are explained based on models like thermally activated flux flow (TAFF) in the light of Kramer’s relation. The normal state just above Tc has a negative temperature co-efficient of resistivity reminiscent of the Anderson localization scenario. The estimated critical field of 27T is more than two times higher than that of Pauli limit. [ABSTRACT FROM AUTHOR]

An experimental technique is presented for studying two-dimensional (2D) ideal fluid vortices in the presence of externally imposed flows, using an electron plasma confined in a Penning-Malmberg trap. This procedure is made possible by an isomorphism between the Drift-Poisson equations governing electron plasma dynamics and the 2D Euler equations describing an ideal fluid. Here, the electron density is the analog of fluid vorticity, and the electric potential that of the fluid stream function. External flows are imposed in 2D using a segmented electrode spanning the length of the plasma. Details of the experimental procedure and data analysis are given, including the capabilities and limitations of the experimental approach. [ABSTRACT FROM AUTHOR]

We study the motion of a counter-rotating vortex pair with the circulations ±Γ move in incompressible fluid. The assumption is made that the core is very thin, that is the core radius σ is much smaller than the vortex radius d such that ε = σ/d ≪ 1. With this condition, the method of matched asymptotic expansion is employed. The solutions of the Navier-Stokes equations and the Biot-Savart law, regarding the inner and outer solutions respectively, are constructed in the form of a small parameter. An asymptotic expansion of the Biot-Savart law near the vortex core provides with the matching condition for an asymptotic expansion for limiting the Navier-Stokes equations for large radius r. The general formula of an anti-parallel vortex pair is established. At leading order O(ε0), we apply the special case in inviscid fluid, the Rankine vortex, a circular vortex of uniform vorticity. Furthermore at leading order O(ε5) we show the traveling speed of a vortex pair. [ABSTRACT FROM AUTHOR]

The hydraulic fluctuations associated with partial load operating conditions of Francis turbines are often periodic and characterized by the presence of a vortex rope. Two types of pressure fluctuations associated with the draft tube surge are identified in the literature. The first is an asynchronous (rotating) pressure fluctuation due to the precession of the helical vortex around the axis of the draft tube. The second type of fluctuation is a synchronous (plunging) fluctuation. The plunging fluctuations correspond to the flow field oscillations in the whole hydraulic passage, and are generally propagated overall in the hydraulic system. The paper introduced a new control method, which consists in injecting a pulsating axial water jet along to the draft tube axis. Nevertheless, the great calling of this control method is to mitigate the vortex rope effects targeting the vortex sheet and corresponding plunging component. In this paper, is presented our 3D numerical investigations with and without pulsating axial water jet control method in order to evaluate the concept. [ABSTRACT FROM AUTHOR]

The adiabatic heater which is the part of the working gas source in the hypersonic wind tunnel was tested in dynamic experiments. They were carried out in a special test bench which provided the off-design modes of the heater performance: there was no mechanism of piston motion damping, and the frame was not mounted. The pressures in the receiver, feed pipes, cylinder working capacity and in the capacity of the pushing gas supplier were measured. The temperature in the working capacity was measured, too. The measurement results show the complex interaction of the mutual motion of the pistons and frame. Simulation of this process permits determining its other parameters such as the distance, velocity, acceleration, force, etc. investigations were carried out at different pressures of the pushing gas and piston motion directions. [ABSTRACT FROM AUTHOR]

The ignition of gaseous premixtures in the cube with regular vortexes describing by time-independent ABC-flow field was investigated numerically in the frame of three-dimensional thermal-diffusion model. The effects of Lewis number, vortex size and the velocity amplitude on ignition energy have been studied. It was found that in the case of fixed velocity amplitude of the ABC-flow, there is a critical eddies size corresponding to the maximal ignition energy. Numerical results show that in large-scale eddies flow, the ignition energy is almost constant until the velocity amplitude exceeds some critical value, then the abrupt linear increase of ignition energy is observed. It is shown that ignition energy is changing very slowly in the range of Lewis numbers from 0.3 to 1.2, and rapidly increases for Lewis numbers large of 1.2. Obtained results coincide with experimental data available in literature and with previous theoretical results obtained for the spherical flame initiation in the quiescent mixtures. [ABSTRACT FROM AUTHOR]

The problems of using the hot-wire method for studying fluctuations in flows are considered when standard approaches and conventional modes cannot be used due to constraints caused either by the flow parameters or by the characteristics and conditions of the experiments. Examples of measurements under conditions of extremely low pressures and beyond the limits of the continuity of the medium in the CO2-laser are given; The use of data of hot-wire measurements for the determination of sources of disturbances in test sections of high-speed wind tunnels is shown; the design of a probe for measurement of concentration of components of the binary gas mixture is described, etc. [ABSTRACT FROM AUTHOR]

The paper presents an application of synthetic jets in the flow control of a jet. The synthetic jet actuator consists of an oscillating membrane operating at high frequency and separating two cavities with exit slots of different geometries. The synthetic jets work as an alternating push-pull system and the generated vortical structure changes the flow direction of the main jet (jet vectoring).The numerical investigations are performed using a RANS solver with an adequate turbulence model and demonstrates a changing of a jet direction. [ABSTRACT FROM AUTHOR]

Performance of jet engine is dependent on the performance of compressor. This paper gives numerical study of performance characteristics for axial compressor. The test rig is present at CSIR LAB Bangalore. Flow domains are meshed and fluid dynamic equations are solved using ANSYS package. Analysis is done for six different speeds and for operating conditions like choke, maximum efficiency & before stall point. Different plots are compared and results are discussed. Shock displacement, vortex flows, leakage patterns are presented along with unsteady FFT plot and time step plot. [ABSTRACT FROM AUTHOR]

The aerodynamic performance analysis of road vehicles depends on the study of engine intake and cooling flow, internal ventilation, tire cooling, and overall external flow as the motion of air around a moving vehicle affects all of its components in one form or another. Due to the complex geometry of these, the aerodynamic interaction between the various body components is significant, resulting in vortex flow and lifting surface shapes. The present study, however focuses on the effects of external aerodynamics only, and in particular on the flow over the lifting surfaces of a common compact car, designed especially for this study. [ABSTRACT FROM AUTHOR]

The cases of the vortex wake decay after the large aircraft are considered for the case of cruise flight and near the ground. It is shown that the scenarios of destruction process are principally different from each other. The physical features of the phenomenon are described and the two models for description of such phenomenon are compared. [ABSTRACT FROM AUTHOR]

The article deals with the analysis of unsteady periodic flow field related to synthetic jet creation. The analyses are based on the data obtained using ANSYS Fluent solver. Numerical results are validated by hot wire anemometry data measured along the jet centerline. The speed of travelling vortex ring is evaluated by using vortex tracking method and by using dynamic mode decomposition method. Vortex identification is based on residual vorticity which allows identifying regions in the flow field where fluid particles perform the rotational motion. The regime of the synthetic jet with Re = 329 and S =19.7 is chosen. Both the vortex tracking and the dynamic mode decomposition based vortex speed evaluation indicate an increase in the vortex speed close to the orifice and then decrease with maximum reaching almost one and half of orifice centerline velocity. The article contains extended version the article presented at the conference AEaNMiFMaE 2016. [ABSTRACT FROM AUTHOR]

The axisymmetric Taylor-vortex flow of a rarefied gas between two coaxial circular cylinders, a rotating inner cylinder and a resting outer one, is investigated numerically for small Knudsen numbers on the basis of the compressible Navier-Stokes (CNS) equations and their appropriate slip boundary conditions. The accuracy of the result as an approximate solution to the Boltzmann equation is confirmed by comparing it with the result obtained by the direct simulation Monte Carlo (DSMC) method for Knudsen numbers of the order of 10-2. The flow field for smaller Knudsen numbers (of the order of 10-3) exhibits a boundary-layer like structure near the cylinders. It is shown that, compared with the cylindrical Couette flow, the velocity slip in the circumferential direction is enhanced in the Taylor-vortex flow. [ABSTRACT FROM AUTHOR]

We present the measurements of the fluctuating component of the flux(vortex)-flow voltage δV(t) about the average in the low-temperature(T) vortex-liquid phase of amorphous MoxSi1-x films. For the thick film δV(t) and broad-band noise originating from the vortex motion is clearly visible in the quantum-vortex-liquid phase, where the amplitude of δV(t) is pronounced and the distribution of δV(t) is anomalously asymmetric, implying the unstational vortex motion. For the thin film the similar unusual vortex motion is observed in nearly the same reduced-T regime. Physical origin responsible for the phenomena is discussed. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

We present the zero temperature molecular dynamics simulation of vortices in low Tc type-II superconductors. We observe power law variation of noise in the dynamical phase. In comparison with the ordered vortex flow region the disordered vortex flow region shows large power law correlation of noise. [ABSTRACT FROM AUTHOR]

The fluctuating component of the flux-flow voltage, δV(t), about the average voltage is measured in the low-temperature (T) liquid phase of amorphous MoxSi1-x films. For the 100-nm-thick film δV(t) originating from the vortex motion is clearly visible in the quantum-yortex-liquid (QVL) phase, where the distribution of δV(t) is asymmetric, suggestive of the unusual vortex motion. For the 6- and 4-nm-thick films, in which the QVL phase is not determined from the resistance vs T curves, the similar unusual vortex motion is observed in nearly the same reduced-T regime. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]