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Vortex dynamics in nonrelativistic version of Abelian Higgs model: Effects of the medium on the vortex motion

Vortex dynamics in nonrelativistic version of Abelian Higgs model: Effects of the medium on the vortex motion

line of Eq. (12) exceeds the velocity of sound. This may result in the Vavilov-Cherenkov damping. We leave this problem for a separate work. The kinetic term becomes strongly modified due to the exchange of fluctuations. The ring vortex motion due to the term [ ˙ X × X ] in the medium consisting of the charged scalar field condensate is possible. The interaction with the fermion asymmetric back- ground results in additional term [X × X ] in equation of motion because of the anomalous current

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Gross Pitaevskii vortex motion with critically scaled inhomogeneities

Gross Pitaevskii vortex motion with critically scaled inhomogeneities

The dynamics of vortices in Gross–Pitaevksii equations have been the subject of much study in the past few decades. The connection between the vortex motion in superfluids, where p(x) ≡ 1, and simplified ODEs was made by Fetter in [11], and it was shown that vortices interact with each through a Coulomb potential. On the other hand, in BECs with nontrivial trapping potentials, p(x) = O(1), it was shown by Fetter and Svidzinsky in [12] that vortices interact solely with the background potential and are carried along level sets of the Thomas–Fermi profile.

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Similarity solutions to an averaged model for superconducting vortex motion

Similarity solutions to an averaged model for superconducting vortex motion

In practice, it is not feasible to use this model directly to simulate the response of a macroscopic superconducting sample because of the vast number of vortices typically found inside such samples. This has led to the search for an averaged model of supercon- ducting motion which is capable of giving an approximate description of the motion of large numbers of vortices. Modelling of this form was first conducted by Brandt [5] on the basis of heuristic arguments. A subsequent formal derivation of an averaged model from (1.1)–(1.2) was made by Chapman [6] in a regime where vortices are sufficiently densely packed, and the magnetic fields correspondingly large, so that the the first term on the right of (1.1) can be neglected. In certain special geometries, such as thin films, this turns out to be a reasonable assumption however in most three-dimensional situations such an assumption leads to a model which is linearly ill-posed [20]. The reason for this pathological behaviour is a three-dimensional vortex instability that occurs wherever there is a component of ∇ ∧ H in the direction of the vortex tangent t; this instability was first noted by Clem [11]. Over a short time scale, the instability causes vortex lines to develop a highly curved spiral structure which invalidates the assumption that the second term on the right-hand side of (1.1) is much larger than the first. A more detailed investigation, carried out in earlier work [18], reveals that the instability grows so as to try to align the vortex tangent perpendicular to the local electric current density j = ∇ ∧ H or, taking an alternative viewpoint, that the resulting vortex motion causes an electric field parallel to the current density j.

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Vortex motion in shallow water with varying bottom topography and zero Froude number

Vortex motion in shallow water with varying bottom topography and zero Froude number

Experimental evidence for the generation of vortex-like structures in shallow water has been given by Oltman-Shay, Howd & Birkemeier (1989) who studied the effect of a current flowing along a beach. Evidence for the generation of vortices (in shallow water) by flow round an obstacle can be found in Van Dyke (1982) which contains an aerial photograph of the flow around a grounded tanker. The marker used to visualize the flow is the oil seeping from the tanker. In Hamm, Masden & Peregrine (1993) observations of an intermittent rip current consisting of vortex pairs propagating seaward is reported. They also remark upon the difficulty of observing large-scale flows without the presence of a marker, such as oil or sediment. Such difficulties led Couder & Basdevant (1986) to experimentally investigate two-dimensional high Reynolds number flows in a soap film forced by a moving disc. The results of this experiment show the generation of coherent vortices and vortex couples.

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Computational study of decaying annular vortex flow using the r ε/k-ε turbulence model

Computational study of decaying annular vortex flow using the r ε/k-ε turbulence model

Figs. 3 and 4 show a comparison between the vortex flow field as predicted by the standard k e model and R e /k e against experimental measurements. The axial velocity predictions of the two models are close, and both models over-pre- dict the axial velocity near to the outer wall. This can be attributed to the complexity of the flow near to the wall, and also to the unsteadiness of the vortex breakdown region where the measurements plotted in Figs. 3 and 4 were conducted. Such region exhibits a sharp drop in the vortex strength, as it is shown later in this article. The standard k e model, however, fails to predict the vortex motion compared to the R e /k e model as shown in Fig. 4. The additional term in the e equation of the R e /k e model damps the dissipation rate predictions by the standard model, in order to take into account the effect of elevated strain rates produced by anisotropic turbulence inherited by swirling flows. This produces enhanced predictions of the forced vortex field, which complies with the theory of postulates that forced vortex regime produces a stabilizing effect on the turbulence field [53,54].

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Hamiltonian formulation of the problem of a single vortex evolution on a beta-plane

Hamiltonian formulation of the problem of a single vortex evolution on a beta-plane

Conclusion. Application of the “elliptic approach” [4] to studying evolution of a single synoptic vortex on the ß-plane has permitted to generalize the earlier- proposed theory by supplementing balance of the forces influencing the vortex with the inertial summands. It is shown that the deduced evolution equations are of the Hamiltonian form in case the non-canonical character of the used set of va- riables is taken into account. The evolution equations describing the vortex core and the trap zone center motion for a particular case of the initially circular vortex with constant vorticity, are written in two ways: the “Lagrangian” form (the va- riables are the trap zone vorticity, and the coordinates of the vortex core and the trap zone center) and the “Euler” one (the variables are the vortex motion velocity components and the trap zone vorticity). Analysis of the “Lagrangian” solution permits to interpret the vortex self-propagation on the ß-plane without basing on the force balance. It is revealed that the vortex core and the trap zone centers are displaced along the meridian; and their synchronous movement is similar to trans- lation of a pair of point vortices with identical intensity but different signs.

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The radial clearance C of the screw conveyor was chosen to be at least 1.5 times larger than the maximum particle size in order to prevent jamming of particles in the clearance space leading to particle attrition and increased energy loss. Also research has shown that the throughput of an enclosed screw conveyor is influenced by the rotational or vortex motion of the bulk material during transportation and degree of fill or fullness of the screw [11, 12]. As the rotational speed of the conveyor increases, the rotational or vortex motion decreases (up to a limiting value) making for a more efficient conveying action. But in the centrifuge the conveying action is low

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Multiphase Flow Simulations through Tarbela Dam Spillways and Tunnels

Multiphase Flow Simulations through Tarbela Dam Spillways and Tunnels

Tarbela dam is one of the largest earth filled dam in the world used for power generation and irrigation pur- poses. Like all reservoirs the sediments inflow in the Tarbela reservoir has resulted in reduction in water storage capacity and is also causing damage to the tunnels, power generating units and ultimately to the plant equipment. This numerical study was performed to predict the flow patterns and characteristics in Tarbela dam. Tunnel 3 and 4 inlets; originally on the bed level were raised in the 3-D model and meshed. Analysis was performed using multiphase flow (water and air) for maximum inflow in the reservoir, i.e., considering summer season and discharging water through different locations, i.e., tunnels and spillways. Pressure, ve- locities, flow rate and free surface height results obtained were found in good agreement with the analytical and existing results where available. Results show uneven discharge through each gate due to maximum ve- locity near exits and overall stagnant phenomena of water within the reservoir. Maximum velocity was ob- served along the spillways outlet. Strong vortex motion was observed near the spillways outlet and tunnel inlets. New design of Tunnels 3 and 4 were suggested to WAPDA in order to decrease the sediment inflow and improvements in design of the spillways were suggested.

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On the behavior of a large scale tumbling vortex flow submitted to compression

On the behavior of a large scale tumbling vortex flow submitted to compression

In this experiment, the intake air is seeded with fine oil droplets that do not modify the fluid properties while being able to track accurately the fluid motion. The illumination source is a copper vapor laser (ACL 45W Oxford Laser). This laser is pulsed with an adjustable repetition rate up to 10 kHz. Mean pulse energies are 6.5 mJ at wavelengths of 510.6 nm and 578.2 nm and their duration lies between 10 ns and 60 ns. A 35 mm drum camera (CORDIN 350) viewing perpendicular to the laser sheet records light scattered by seeding particles with an acquisition rate up to 8000 frames/s. The film type is ILFORD HP5+, developed to its nominal speed of 400 ASA with KODAK TMAX developer. To extract quantitative information from images of particle on the negative, a high-resolution film scanner (KODAK RFS 2035) is used. To apply a cross-correlation approach, concerns peculiars to film support and the digitalization stage have to be taken into account. A special film holder was designed to fit in the scanner in order to translate the film accurately and to press it between two strip of glass. Each image of particle on the film was digitized in 8 bits with a 2000 dpi spatial resolution. Each image consists in 1400x1050 pixels with a resolution of approximately 20 pixels/mm.

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Dynamics of a levitated microparticle in vacuum trapped by a perfect vortex beam : three dimensional motion around a complex optical potential

Dynamics of a levitated microparticle in vacuum trapped by a perfect vortex beam : three dimensional motion around a complex optical potential

To understand its complex orbital cycle, we separate the par- ticle motion into inward and outward phases. In the initial state, the microparticle is trapped at the Bessel annular beam (z = 30 µm) which has the maximum beam intensity in the field. OAM with a topological charge ` = 15 is encoded onto both the Bessel and the perfect vortex beams by the SLM, which is transferred to the microparticle via light scattering and sets the microparticle into rotation. Depending on the topological charge of the beam and the orbital rate and the orbital radius of the particle, the inertial force (centrifugal in this case) increases the orbital radial position with respect to the radial trap. However, the particle only remains trapped while the orbital frequency is lower than the trap frequency, i.e. once the inertial force exceeds the radial trapping force, the particle is horizontally launched into free space (outward phase) and falls due to gravity, until the force due to the perfect vortex beam (r = 25 µm; z = 0 µm) provides sufficient levitation. Due to both the scattering and gradient forces acting on the particle, it is guided along the beam

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The interaction of a vortex ring with a sloped sediment layer: critical criteria for incipient grain motion

The interaction of a vortex ring with a sloped sediment layer: critical criteria for incipient grain motion

and made flat prior to each repeat. Once the appropriate stroke time for critical conditions had been identified, the velocity field of the corresponding vortex ring was measured using particle imaging velocimetry (PIV), the details of which are given below in Sec. II B. Note that the PIV data captured the ring flow-field over the entire impact region, and at each stage during the interaction. To minimise the experimental errors associated with the incremental increase of the pump stroke time, the entire procedure described above was repeated several times (for each sediment type and bed slope) so that an average could be taken. The velocity data were also used to directly measure U and D for each vortex ring (from the period before the ring’s trajectory was affected by the sediment layer). The values of U and D reported here are the corresponding averages obtained from the repeated experiments, which had typical variability of ±6% and ±4%, respectively. Over the range of critical impact conditions analysed in this article, the corresponding vortex ring Reynolds number, Re = UD/ν, was varied between 450 and 3360 (where 0.8 ≤ D/D 0 ≤ 1.2).

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Entrapping of a vortex pair interacting with a fixed point vortex revisited  I  Point vortices

Entrapping of a vortex pair interacting with a fixed point vortex revisited I Point vortices

The problem of a pair of point vortices impinging on a fixed point vortex of arbitrary strengths [E. Ryzhov and K. Koshel, EPL 102, 44004 (2013)] is revisited and investi- gated comprehensively. Although the motion of pair of point vortices is established to be regular, the model presents a plethora of possible bounded and unbounded solutions with complicated vortex trajectories. The initial classification [E. Ryzhov and K. Koshel, EPL 102, 44004 (2013)] revealed that pair could be compelled to perform bounded or unbounded motion without giving a full classification of either of those dynamical regimes. The present work capitalizes upon the previous results and introduces a finer classification with a multitude of possible regimes of motion. Regimes of bounded motion for the vortex pair entrapped near the fixed vortex or of unbounded motion, when the vortex pair moves away from the fixed vortex, can be categorized by varying the two governing parameters: (i) the ratio of the distances between pair’s vortices and the fixed vortex, and (ii) the ratio of the strengths of the vortices of the pair and the strength of the fixed vortex. In particular, a bounded motion regime where one of pair’s vortices does not rotate about the fixed vortex is revealed. In this case, only one of pair’s vortices rotates about the fixed vortex, while the other one oscillates at a certain distance. Extending the results obtained with the point-vortex model to an equivalent model of finite size vortices is the focus of a second paper.

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Ricci magnetic geodesic motion of vortices and lumps

Ricci magnetic geodesic motion of vortices and lumps

geometry arises as the infinite electric charge limit of a certain semi-local vortex model [3, 12], so the RMG flow may be relevant to the low energy dynamics of such vortices in the presence of a Chern-Simons term. However, our main interest in it concerns the question of completeness. Since RMG flow proceeds with constant speed, it is immediate that RMG flow on any geodesically (or, equivalently, metrically) complete k¨ahler manifold is complete, that is, given any initial data x ∈ M , v ∈ T x M, there is a corresponding RMG curve α : R → M (well-

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Characteristics of vortex formation and thrust performance in drag based paddling propulsion

Characteristics of vortex formation and thrust performance in drag based paddling propulsion

Muskrats and ducklings employing a drag-based propulsion mode use a specific stroke angle for a given body speed (Fish, 1984; Algeldinger and Fish, 1995). Our experiment to find the optimal stroke angle was meant to investigate an important flow phenomenon that can influence a preferred stroke angle. From repeated paddling motions of the propulsor, it has been observed that the ring-like vortex structure is shed into the wake (Algeldinger and Fish, 1995; Drucker and Lauder, 1999). The closed vortex structure in the wake originates from a starting vortex (a tip vortex and side-edge vortices in our case) and a stopping vortex. When the propulsor decelerates its power strokes, the stopping vortex starts to shed from the plate. The shedding process continues even after the propulsor finishes its power stroke. How the stopping vortex is shed depends on the shape and flexibility of the plate and the angular velocity program. For example, the stopping vortex sheds smoothly for the sinusoidal velocity program whereas it sheds abruptly for the trapezoidal velocity program because of its short deceleration time.

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Experimental investigation of the flow-induced vibration of a curved cylinder in convex and concave configurations

Experimental investigation of the flow-induced vibration of a curved cylinder in convex and concave configurations

Experiments have been conducted to investigate the two-degree-of-freedom vortex-induced vibration (VIV) response of a rigid section of a curved cir- cular cylinder with low mass-damping ratio. Two curved configurations, a concave and a convex, were tested regarding the direction of the flow, in addition to a straight cylinder that served as reference. Amplitude and frequency responses are presented versus reduced velocity for a Reynolds number range between 750 and 15,000. Results for the curved cylinders with concave and convex configurations revealed significantly lower vibra- tion amplitudes when compared to the typical VIV response of a straight cylinder. However, the concave cylinder showed relatively higher amplitudes than the convex cylinder which were sustained beyond the typical synchro- nisation region. We believe this distinct behaviour between the convex and the concave configurations is related to the wake interference taking place in the lower half of the curvature due to perturbations generated in the hor- izontal section when it is positioned upstream. Particle-image velocimetry (PIV) measurements of the separated flow along the cylinder highlight the effect of curvature on vortex formation and excitation revealing a complex fluid-structure interaction mechanism.

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Hidden momentum of electrons, nuclei, atoms and molecules

Hidden momentum of electrons, nuclei, atoms and molecules

We consider the positions and velocities of electrons and spinning nuclei and demonstrate that these particles harbour hidden momentum when located in an electromagnetic field. This hidden momentum is present in all atoms and molecules, however it is ultimately canceled by the momentum of the electromagnetic field. We point out that an electron vortex in an electric field might harbour a comparatively large hidden momentum and recognize the phenomenon of hidden hidden momentum.

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Numerical Examination on the Effect of Internal Fluid Presssure on the Hydrodynamic Response of a Marine Riser

Numerical Examination on the Effect of Internal Fluid Presssure on the Hydrodynamic Response of a Marine Riser

In the present work, a TDOF riser model with internal pressure variation was studied and the corresponding vortex shedding pattern was analyzed.Also, different hydrodynamic characteristics of riser like lift and drag forces were calculated in ANSYS FLUENT. The vortices evoked from behind the cylinder, at the wake portion was very much distinct in the case of riser without internal pressure. Drag coefficient showed a higher value for 60 Pa and lift coefficient was higher for 80Pa.The frequency of oscillations was calculated for one cycle and was found to increase with increase in fluid pressure. Also, at 70 Pa pressure, the cylinder shows a tendency to beat at a reduced velocity of Ur=5 and a mass ratio of 0.55.At 70 Pa pressure, the riser is observed to oscillate in the CF direction with a frequency equal to the vortex shedding frequency. As a result of which synchronization region is developed and together they resonate which results in failure of the riser system.

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A numerical and analytical study of vortex rings with swirl

A numerical and analytical study of vortex rings with swirl

Once a vortex ring is constructed by the method of the previous section, we have available an exact solution of the Euler equations of incompressible, inviscid ow. We can predict the behavior of disturbances to this exact solution by numerical simulations, as described subsequently, or by analytical treatment of instabilities. Although there has been considerable research on the stability of thin rings, little is known about the stability of exact rings with swirl. In this section we discuss the stability of general vortex rings using a WKB type method developed by Lifschitz and Hameiri 12, 13, 14, 15], valid for short wavelengths and small amplitude perturbations. Once the growth rates of these instabilities have been calculated, we can compare them with the results of time-dependent numerical simulations. This gives us an opportunity to determine the general applicability of the WKB method.

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Laminar-turbulent transition regimes in the conical Taylor-Couette flow system

Laminar-turbulent transition regimes in the conical Taylor-Couette flow system

components) and axi-symmetric (Fig. 5). The three- dimensional character of the flow is the result of the imbalance of the centrifugal forces in the annulus: indeed, the linear variation of the radius versus the conical axial position z induces a linear variation of these centrifugal forces. The flow observed in any azimuthal plane corresponds to a large loop going up along the inner cone and down along the outer cone and turning at the end plates [1]. These end plates being fixed with no-slip conditions, the centrifugal forces decrease in their vicinity. This effect will promote end recirculations, in the direction of the main loop at the bottom and in the opposite direction at the top. The recirculation at the bottom will only reinforce the main loop. In contrast, the recirculation at the top will progressively generate a vortex in counter-rotation with the main loop. Due to the axi-symmetry of the flow, this vortex (known as Ekman vortex) is in fact a toroidal cell. In the small gap situations considered here, it has not been possible to provide evidence of this Ekman vortex.

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The Future of Wind mill Blade Less Windmill

The Future of Wind mill Blade Less Windmill

This is a wind generator without blades. Instead of capturing energy via the rotational motion of a turbine the Vortex takes advantage of what’s known as vortices an aerodynamic effect that occurs when wind breaks against a solid structure[1] .By this project, we are going to generate electricity by using the bladeless windmill. This wind mill will have no blades. It will generate electricity by using oscillation due to wind. It works on principle of electromagnetic induction or vibrations. Here, electricity can be generated by using linear alternator or piezoelectric material. The kinetic energy is converted into electricity by an alternator to improve the efficiency of the energy being gather working on a wind turbine that operates on the principle of vortices an aerodynamic effect of wind that turns wind into kinetic energy that can be used as electricity. The advantages of this turbine over our present ones are: there are no gears, bolts or mechanical moving parts so they are cheaper to manufacture and maintain. It would cost less than the conventional turbine with its major costs for the blades and support system.

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