scholarly journals Parallel Simulation of HGMS of Weakly Magnetic Nanoparticles in Irrotational Flow of Inviscid Fluid

2014 ◽  
Vol 2014 ◽  
pp. 1-12
Author(s):  
Kanok Hournkumnuard ◽  
Banpot Dolwithayakul ◽  
Chantana Chantrapornchai
Keyword(s):  
Magnetic Nanoparticles ◽  
Particle Transport ◽  
Parallel Simulation ◽  
Outer Radius ◽  
Inviscid Fluid ◽  
Wire Radius ◽  
Problem Size ◽  
Irrotational Flow ◽  
The Wire ◽  
Weakly Magnetic

The process of high gradient magnetic separation (HGMS) using a microferromagnetic wire for capturing weakly magnetic nanoparticles in the irrotational flow of inviscid fluid is simulated by using parallel algorithm developed based on openMP. The two-dimensional problem of particle transport under the influences of magnetic force and fluid flow is considered in an annular domain surrounding the wire with inner radius equal to that of the wire and outer radius equal to various multiples of wire radius. The differential equations governing particle transport are solved numerically as an initial and boundary values problem by using the finite-difference method. Concentration distribution of the particles around the wire is investigated and compared with some previously reported results and shows the good agreement between them. The results show the feasibility of accumulating weakly magnetic nanoparticles in specific regions on the wire surface which is useful for applications in biomedical and environmental works. The speedup of parallel simulation ranges from 1.8 to 21 depending on the number of threads and the domain problem size as well as the number of iterations. With the nature of computing in the application and current multicore technology, it is observed that 4–8 threads are sufficient to obtain the optimized speedup.

ATOMISTIC SIMULATION OF TORSIONAL VIBRATION AND PLASTIC DEFORMATION OF FIVE-FOLD TWINNED COPPER NANOWIRES

2014 ◽  
Vol 11 (supp01) ◽  
pp. 1344010 ◽  
Author(s):  
Y. G. ZHENG ◽  
Y. T. ZHAO ◽  
H. F. YE ◽  
H. W. ZHANG ◽  
Y. F. FU
Keyword(s):  
Plastic Deformation ◽  
Torsional Vibration ◽  
Partial Dislocation ◽  
Dislocation Nucleation ◽  
Activation Process ◽  
Torsional Angle ◽  
Wire Radius ◽  
Wire Length ◽  
Deformation Behaviors ◽  
The Wire

In this paper, atomistic simulations have been conducted to investigate the torsional mechanical behaviors of five-fold twinned nanowires (FTNs), including the torsional vibration properties, elasto-plastic deformation behaviors and activation process of the first partial dislocation nucleation. Simulation results show that the fundamental torsional vibration frequency is inversely proportional to the wire length and is independent of the wire radius. Provided that an effective shear modulus of FTNs is used, the classic elastic torsional theory may be applicable to nanoscale. Furthermore, it is found that the plastic deformation of FTNs is dominated by partial dislocation activities. The normalized critical torsional angle corresponding to the onset of plastic deformation increases with the decrease of the wire radius and temperature, while it is almost independent of the wire length and loading rate. In addition, the activation energy of the first partial dislocation nucleation is about several electric voltages and decreases with the increase of the wire radius and applied torsional load.

Design Study of Beam Window for Accelerator-Driven System With Subcriticality Adjustment Rod

2018 ◽  
Author(s):  
Takanori Sugawara ◽  
Yuta Eguchi ◽  
Kazufumi Tsujimoto ◽  
Hironari Obayashi ◽  
Hiroki Iwamoto ◽  
...  
Keyword(s):  
Proton Beam ◽  
Particle Transport ◽  
Factor Of Safety ◽  
Beam Current ◽  
Outer Radius ◽  
Coupled Analysis ◽  
Design Issues ◽  
Design Study ◽  
Driven System ◽  
Accelerator Driven System

Engineering feasibility of the beam window is one of the design issues in the accelerator-driven system (ADS). This study aims to perform the coupled analysis for the feasible beam window concept. To mitigate the design condition, namely to reduce the required proton beam current, subcriticality adjustment rod (SAR) was installed to the ADS core. The burnup analysis was performed for the ADS core with SAR and the results indicated that the maximum proton beam current during the burnup cycle was reduced from 20 to 13.5 mA. Based on the burnup analysis result, the coupled analysis; particle transport, thermal hydraulics and structural analyses, was performed. As the final result, the following design; the hemisphere shape, the outer radius = 180 mm, the thickness at the top of the beam window = 1.5 mm, and the factor of safety for the buckling = 3.8, was presented. The buckling pressure was almost same as the previous one and more feasible beam window concept was presented through this study.

Flow of an inviscid fluid past a sphere in a pipe

1964 ◽  
Vol 18 (4) ◽  
pp. 587-594 ◽  
Author(s):  
Wei Lai
Keyword(s):  
Swirling Flow ◽  
Small Diameter ◽  
Approximate Solutions ◽  
Vortex Sheet ◽  
Inviscid Fluid ◽  
Irrotational Flow ◽  
Inviscid Incompressible Fluid ◽  
Different Types ◽  
Lee Waves ◽  
Angular Velocities

The problem of flow of an inviscid, incompressible fluid inside a circular pipe, with a sphere on the axis of the pipe, has been studied by Lamb (1936) (irrotational flow), Long (1953) and Fraenkel (1956) (swirling flow). Because of the difficulty of satisfying all the boundary conditions in the problem, only approximate solutions, valid for spheres of small diameter (compared with that of the pipe) have been obtained. In this paper, it is found that by introducing a vortex sheet over a segment of the diameter of the sphere, flow patterns can be obtained by an inverse method for the case of large spheres. Four different types of flow are considered: (1) irrotational flow, (2) swirling flow with constant axial and angular velocities far upstream, without lee waves, (3) swirling flow with constant axial and angular velocities far upstream, with lee waves, and (4) rotational flow with a paraboloidal velocity distribution far upstream.

The transient electromagnetic response of a magnetic or superparamagnetic ground

Geophysics ◽  
1984 ◽  
Vol 49 (7) ◽  
pp. 854-860 ◽  
Author(s):  
T. Lee
Keyword(s):  
Transient Response ◽  
Direct Current ◽  
Free Space ◽  
Electromagnetic Response ◽  
Time Constants ◽  
True Value ◽  
Transient Electromagnetic ◽  
Current Value ◽  
The Wire ◽  
Weakly Magnetic

The effect of superparamagnetic minerals on the transient response of a uniform ground can be modeled by allowing the permeability of the ground μ to vary with frequency ω as [Formula: see text] Here [Formula: see text] and [Formula: see text] are the upper and lower time constants for the superparamagnetic minerals and [Formula: see text] is the direct current value of the susceptibility. For single‐loop data it is found that the voltage will decay as 1/t, provided that [Formula: see text] and [Formula: see text] Here, a is the radius of the wire loop and b is the radius of the wire, t represents time and [Formula: see text] is the permeability of free space. Even if a separate transmitter and receiver are used, the transient will still be anomalous. For this case the 1/t term in the equations is less important, and more prevalent now is the [Formula: see text] term. These results show that a uniform ground behaves in a similar way to a ground which only has a thin superparamagnetic layer. A difference is that whereas the amplitude of the 1/t term could be drastically reduced by using a separate receiver, this is not the case for a uniform ground. A magnetic ground for late times will decay as [Formula: see text]. However, if the conductivity of the ground is estimated from apparent conductivities it will be found that the value of the conductivity will be incorrect by a factor that is related to the susceptibility [Formula: see text] of the ground. For a weakly magnetic ground the estimated conductivity [Formula: see text] is related to the true value of the conductivity [Formula: see text].

scholarly journals Supercritical flow of an ideal fluid over a spillway

1977 ◽  
Vol 20 (2) ◽  
pp. 211-225
Author(s):  
I. L. Collings ◽  
R. Grimshaw
Keyword(s):  
Froude Number ◽  
Ideal Fluid ◽  
Asymptotic Expansions ◽  
Matched Asymptotic Expansions ◽  
Inviscid Fluid ◽  
Supercritical Flow ◽  
Irrotational Flow ◽  
Outer Expansion

AbstractThe irrotational flow of an incompressible, inviscid fluid over a spiliway is considered. The reciprocal ε of the Froude number is taken to be small and the method of matched asymptotic expansions is applied. The bed of the spillway is horizontal far upstream and makes an angle α with the horizontal far downstream. The inner expansion is valid upstream and over the spillway, but is invalid far downstream. The outer expansion which is valid downstream fails to satisfy the upstream conditions. Unknown constants in the outer expansion are determined by the matching and composite expansions obtained.

Analysis of Wire Drawing and Extrusion Through Conical Dies of Small Cone Angle

1963 ◽  
Vol 85 (1) ◽  
pp. 89-95 ◽  
Author(s):  
Betzalel Avitzur
Keyword(s):  
Cone Angle ◽  
Wire Drawing ◽  
Power Balance ◽  
Wire Radius ◽  
Process Variables ◽  
Power Losses ◽  
Uniaxial Load ◽  
The Wire ◽  
Analytical Expressions ◽  
Entrance Velocity

Analytical expressions are derived for the required front pull for wire drawing, as well as the back push for extrusion. The effect of each of the process variables on these forces is presented graphically. The process variables are: the cone’s semiangle (α) initial (Ri) and final (Rf) wire radius, material yield limit (σ0) at uniaxial load, back pull (σxb) and front pull (σxf), coefficient of friction (μ) or shear factor (m), die land (L), exit velocity (vf), and entrance velocity (vi). The power balance is set for these powers: (1) Internal power of deformation of the wire, (2) power involved with the back force on the wire, (3) power involved with the front force on the wire, (4) power losses due to friction between the wire and the die.

scholarly journals Parallel simulation of particle transport in an advection field applied to volcanic explosive eruptions

2016 ◽  
Vol 89 ◽  
pp. 174-185 ◽  
Author(s):  
Pierre Künzli ◽  
Kae Tsunematsu ◽  
Paul Albuquerque ◽  
Jean-Luc Falcone ◽  
Bastien Chopard ◽  
...  
Keyword(s):  
Particle Transport ◽  
Parallel Simulation ◽  
Explosive Eruptions

Melting of a Wire Anode Followed by Solidification: A Three-Phase Moving Interface Problem

2003 ◽  
Vol 125 (4) ◽  
pp. 661-668 ◽  
Author(s):  
S. S. Sripada ◽  
Ira M. Cohen ◽  
P. S. Ayyaswamy
Keyword(s):  
Ambient Medium ◽  
Boundary Surface ◽  
Interface Problem ◽  
Time Interval ◽  
Wire Radius ◽  
Ambient Conditions ◽  
Electrode Gap ◽  
Three Phase ◽  
The Wire ◽  
Solid Liquid

A fine metallic wire electrode is heated from below (by an electric discharge) causing melting and roll-up into a ball by surface tension. After the heating is terminated, a solidification front progresses through the melt until a solid ball is formed and cooled to ambient conditions. In this paper we numerically simulate the heating, melt motion and roll up and subsequent cooling and solidification. This is a three-phase problem (solid, liquid, and the ambient medium—plasma/gas) with two simultaneously moving phase interfaces, the outer one tracked by orthogonal grid generation conformal with the evolving boundary surface at each time interval. A novel observation in this study is that the wire end first drops until the melt radius equals the wire radius and then it begins to roll up into a ball consuming the wire. In other words, the inter-electrode gap first reduces and subsequently increases during an electronic flame off (EFO) discharge heating/phase-change process.

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