Visualization of Taylor-Couette flow in superfluid helium

Bielert, F.; Stamm, G.

doi:10.1016/0011-2275(93)90220-i

Cited by 32 publications

(9 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Hollerbach (1998) also found evidence of time-dependent, asymmetric Taylor vortices in medium gaps ( ¼ 0:336). However, superfluid analogs of these experiments are hard to perform, partly because of problems with visualization techniques (Bielert & Stamm 1993). Numerical HVBK simulations have been performed in cylindrical Taylor-Couette geometries (Henderson et al 1995;Henderson 2001;Henderson & Barenghi 2000), delivering good agreement with experiments, but not yet in the more challenging spherical Couette geometry.…”

Section: Introductionmentioning

confidence: 99%

Global Three‐dimensional Flow of a Neutron Superfluid in a Spherical Shell in a Neutron Star

Peralta¹,

Melatos²,

Giacobello³

et al. 2005

ApJ

139

View full text Add to dashboard Cite

We integrate for the first time the hydrodynamic Hall-Vinen-Bekarevich-Khalatnikov equations of motion of a 1 S 0 -paired neutron superfluid in a rotating spherical shell, using a pseudo-spectral collocation algorithm coupled with a time-split fractional scheme. Numerical instabilities are smoothed by spectral filtering. Three numerical experiments are conducted, with the following results. (1) When the inner and outer spheres are put into steady differential rotation, the viscous torque exerted on the spheres oscillates quasi-periodically and persistently (after an initial transient). The fractional oscillation amplitude ($10 À2 ) increases with the angular shear and decreases with the gap width.(2) When the outer sphere is accelerated impulsively after an interval of steady differential rotation, the torque increases suddenly, relaxes exponentially, then oscillates persistently as in (1). The relaxation timescale is determined principally by the angular velocity jump, whereas the oscillation amplitude is determined principally by the gap width. (3) When the mutual friction force changes suddenly from Hall-Vinen to Gorter-Mellink form, as happens when a rectilinear array of quantized Feynman-Onsager vortices is destabilized by a counterflow to form a reconnecting vortex tangle, the relaxation timescale is reduced by a factor of $3 compared to (2), and the system reaches a stationary state in which the torque oscillates with fractional amplitude $10 À3 about a constant mean value. Preliminary scalings are computed for observable quantities such as angular velocity and acceleration as functions of the Reynolds number, angular shear, and gap width. The results are applied to the timing irregularities (e.g., glitches and timing noise) observed in radio pulsars.

show abstract

Section: Introductionmentioning

confidence: 99%

Global Three‐dimensional Flow of a Neutron Superfluid in a Spherical Shell in a Neutron Star

Peralta¹,

Melatos²,

Giacobello³

et al. 2005

ApJ

139

View full text Add to dashboard Cite

show abstract

“…The third flow is Couette flow between two infinitely long, concentric, rotating cylinders. Despite the large number of experiments (see the review by Donnelly & LaMar 1988) and the early pioneering theoretical attempts of Chandrasekhar & Donnelly (1957) and Snyder (1974), it took a long time to understand the nature of helium Couette flow and make contact between theory (Barenghi & Jones 1987;Barenghi 1992) and experiments (Swanson & Donnelly 1991;Bielert & Stamm 1993). Recent theoretical work on Couette flow includes the study of nonlinear Taylor flow (Henderson, Barenghi & Jones 1995;Henderson & Barenghi 1994) and provides the best test of the validity of the HVBK model.…”

Section: Introductionmentioning

confidence: 99%

“…Unlike water, helium II cannot be easily visualized, and they were misled by the analogy with classical Couette flow in which the Taylor cells have size of the order of the gap's width D for which if H/D is sufficiently large end effects do not matter. There is only one experiment in which a successful flow visualization was carried out in helium II using glass microspheres, but it involved turbulent flows (Bielert & Stamm 1993). So one of our aims is to provide some 'theoretical flow visualization' and highlight similarities and differences between the flow patterns of helium II and those of a classical Navier-Stokes fluid.…”

Section: Introductionmentioning

confidence: 99%

The anomalous motion of superfluid helium in a rotating cavity

Henderson

Barenghi

2000

J. Fluid Mech.

View full text Add to dashboard Cite

We numerically solve the nonlinear two-fluid Hall–Vinen–Bekharevich–Khalatnikov (HVBK) equations for superfluid helium confined inside a short Couette annulus. The outer cylinder and the ends of the annulus are held fixed whilst the inner cylinder is rotated. This simple flow configuration allows us to study how the vortex lines respond to a shear in the presence of boundaries. It also allows us to investigate further the boundary conditions associated with the HVBK model. The main result of our investigation is the anomalous motion of helium II when compared to a classical fluid. The superfluid Ekman cells always rotate in the opposite sense to a classical Navier–Stokes fluid due to the mutual friction between the two fluids, whilst the sense of rotation of the normal fluid Ekman cells depends on the parameter range considered. We also find that the tension of the vortex lines forces the superfluid to rotate about the inner cylinder almost like a rigid column.

show abstract

“…However, for liquid helium, such techniques have not kept pace, in part due to the extremely low temperature and low density of the fluid. A number of early efforts were devoted to producing macroscopic particles for qualitative investigations (10)(11)(12) and the challenge of producing neutrally buoyant particles that faithfully follow the complex flow fields has been the main impediment to quantitative advancement. In addition, several attempts have been made to visualize fluid dynamics in superfluid helium with microscopic tracers, which include neutron absorption tomography, using 3 He particles (13), and acoustic cavitation imaging, using electron bubbles (14).…”

Section: Visualization Techniquesmentioning

confidence: 99%

Visualization of two-fluid flows of superfluid helium-4

Guo

Mantia

Lathrop

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

114

View full text Add to dashboard Cite

Cryogenic flow visualization techniques have been proved in recent years to be a very powerful experimental method to study superfluid turbulence. Micron-sized solid particles and metastable helium molecules are specifically being used to investigate in detail the dynamics of quantum flows. These studies belong to a well-established, interdisciplinary line of inquiry that focuses on the deeper understanding of turbulence, one of the open problem of modern physics, relevant to many research fields, ranging from fluid mechanics to cosmology. Progress made to date is discussed, to highlight its relevance to a wider scientific community, and future directions are outlined. The latter include, e.g., detailed studies of normal-fluid turbulence, dissipative mechanisms, and unsteady/oscillatory flows. He is used as a coolant for superconducting magnets and infrared detectors (2), to astrophysics, where superfluidity is invoked to explain glitches in the rotation of neutron stars (3, 4) and the formation of cosmic strings (5, 6). More recently, superfluidity has been used to describe the collective behavior of birds (7) and a cosmological model has been used to obtain results relevant to superfluid turbulence (8). The latter form of turbulence, occurring in quantum fluids, is indeed an especially interesting topic because of its quantum peculiarities and its similarity to classical turbulence. Superfluids, in which turbulence can be directly visualized and studied, include superfluid 4 He and atomic Bose-Einstein condensates (9). Due to the limit of small sample volumes, the experimental study of turbulence in Bose-Einstein condensates has hardly begun. The development of visualization techniques applicable to superfluid 4 He is thus essential, if our understanding of quantum turbulence is to make significant progress in the near future.Superfluid 4 He is viewed as consisting of two interpenetrating fluids. The gas of thermal excitations forms the normal component, which can be considered as a viscous fluid. The superfluid component is inviscid and its rotational motion is possible only in the presence of topological defects, in the form of quantized vortex filaments. Turbulence in the superfluid component therefore takes the form of a tangle of quantized vortex lines. Turbulence in the normal fluid is more conventional, although the interaction between the normal fluid and the vortices leads to the nonclassical force of mutual friction between the two fluids. Turbulence in such a system can exhibit a behavior that is similar to that found in a classical fluid; but it may take forms that are unknown in classical fluid mechanics: for example, forms relevant to a fluid in which there is no viscous dissipation, and those that depend on the coexistence of the two fluids. Study of quantum turbulence can therefore enrich our knowledge of turbulence in general, as well as being interesting in its own right. Visualization TechniquesFlow visualization techniques have been developed to a high degree of precision and speed for clas...

show abstract

Visualization of Taylor-Couette flow in superfluid helium

Cited by 32 publications

References 7 publications

Global Three‐dimensional Flow of a Neutron Superfluid in a Spherical Shell in a Neutron Star

Global Three‐dimensional Flow of a Neutron Superfluid in a Spherical Shell in a Neutron Star

The anomalous motion of superfluid helium in a rotating cavity

Visualization of two-fluid flows of superfluid helium-4

Contact Info

Product

Resources

About