Taylor Column Research Articles

Mixing and Water Mass Transformation Over Discovery Bank, in the Weddell‐Scotia Confluence of the Southern Ocean

AbstractThe South Scotia Ridge, in the Atlantic sector of the Southern Ocean, is a key region for water mass modification. It is the location of the Weddell‐Scotia Confluence, an area of reduced stratification which separates the Weddell Gyre to the south and the Antarctic Circumpolar Current to the north, and which receives input of shelf waters from the tip of the Antarctic Peninsula. To elucidate the transformations over the ridge, we focus on one of its largest seamounts, Discovery Bank, which has previously been observed as hosting a stratified Taylor column that retains water for months to years, during which time water masses are entrained from north and south of the Weddell Front and steadily mixed. Data from ship‐deployed sensors and autonomous platforms are analyzed to quantify and understand the diapycnal mixing, heat fluxes and water mass transformations over the bank. Ocean glider and free‐profiling drifting float data show that the mid‐depth temperature maximum of the Circumpolar Deep Water (CDW) is eroded between the northern and southern sides of the bank, while diapycnal diffusivity is enhanced by up to an order‐of‐magnitude over its steeply sloping portions. This is accompanied by heat fluxes from the CDW layer being increased by up to a factor of six, which may contribute to a reduction in mid‐depth stratification. Tidal model analysis shows that the southern side of the bank hosts strong barotropic to baroclinic energy conversion (>150 N m−2), emphasizing the role of internal tides in modulating water mass transformations in the Confluence.

Three-Dimensional Structure of Mesoscale Eddies and Their Impact on Diapycnal Mixing in a Standing Meander of the Antarctic Circumpolar Current

Mesoscale eddies are known to enhance diapycnal mixing in the ocean, yet direct observation of this effect remains a significant challenge, especially in the robust Antarctic Circumpolar Current (ACC). To quantify the diapycnal mixing induced by mesoscale eddies in the standing meander of the ACC, satellite altimeter and Argo profile data were combined to composite eddies, where the 1.6 m dynamic height contour was used for the first time instead of the climatological Northern Sub-Antarctic Front (SAFN) to define the northern boundary of the ACC to eliminate the influence of frontal shift. The 3D structures of the composite anticyclonic/cyclonic eddy (CAE/CCE) were obtained. Both the CAE and CCE were similar in shape to Taylor columns, from sea surface to the neutral surface of 28.085 kgm−3 (1689 ± 66 dbar) for the CAE, and from sea surface to 28.01 kgm−3 (1491 ± 202 dbar) for the CCE. On the same neutral surface, the diffusivity (κ) inside the CCE was one to two orders of magnitude higher than that inside the CAE. Vertically, the maximum influence depth of the CCE on κ reached 1200 dbar, while for the CAE, it reached 800 dbar, where κ exceeded O(10−4) m2s−1, and κ gradually decreased from these depths downwards.

The drag on a rising sphere along the axis in a short rotating cylinder of fluid: revisiting the data and theory

We revisit the problem of a solid sphere rising slowly in a rotating short container filled with a slightly viscous fluid, with emphasis on the drag force. The data of the classical experiments of Maxworthy (J. Fluid Mech., vol. 31, 1968, pp. 643–655) and recent experiments of Kozlov et al. (Fluids, vol. 8 (2), 2023, paper 49), and the available geostrophic and quasi-geostrophic theories, are subjected to a novel scrutiny by combined reprocessing and comparisons. The measured drag is, consistently, about 20 % lower than the geostrophic prediction (assuming that flow is dominated by the Ekman layers, while in the inviscid cores the Coriolis acceleration is supported by the pressure gradient). The major objective is the interpretation and improvement of the gap between data and predictions. We show that the data cover a small range of relevant parameters (in particular the Taylor number $T$ and the height ratio $H$ of cylinder to particle diameter) that precludes a thorough and reliable assessment of the theories. However, some useful insights and improvements can be derived. The hypothesis that the discrepancy between data and the geostrophic prediction is due to inertial effects (not sufficiently small Rossby number $Ro$ in the experiments) is dismissed. We show that the major reason for the discrepancy is the presence of relatively thick Stewartson layers about the cylinder (Taylor column) attached to the sphere. The $1/3$ layer displaces the boundary condition of the angular velocity ( $\omega = 0$ ) outside the radius of the particle. This observation suggests a semi-empirical correction to the theoretical quasi-geostrophic predictions (which takes into account the Ekman layers and the $1/4$ Stewartson layers); the corrected drag is in fair agreement with the data. We demonstrate that the inertial terms are negligible for $Ro\,T^{1/2} <0.4$ . We consider curve-fit approximations, and point out some persistent gaps of knowledge that require further experiments and simulations.

Taylor columns and inertial-like waves in a three-dimensional odd viscous liquid

Odd viscous liquids are endowed with an intrinsic mechanism that tends to restore a displaced particle back to its original position. Since the odd viscous stress does not dissipate energy, inertial oscillations and inertial-like waves can become prominent in such a liquid. In this paper, we show that an odd viscous liquid in three dimensions may give rise to such axially symmetric waves and also to plane-polarized waves. We assume tacitly that an anisotropy axis giving rise to odd viscous effects has already been established, and proceed to investigate the effects of odd viscosity on fluid flow behaviour. Numerical simulations of the full Navier–Stokes equations show the existence of inertial-like waves downstream of a body that moves slowly along the axis of an odd viscous liquid filled cylinder. The wavelength of the numerically determined oscillations agrees well with the developed theoretical framework. When odd viscosity is the dominant effect in steady motions, a modified Taylor–Proudman theorem leads to the existence of Taylor columns inside such a liquid. Formation of the Taylor column can be understood as a consequence of helicity segregation and energy transfer along the cylinder axis at group velocity, by the accompanying inertial-like waves, whenever the reflection symmetry of the system is lost. A number of Taylor column characteristics known from rigidly rotating liquids are recovered here for a non-rotating odd viscous liquid. These include counter-rotating swirling liquid flow above and below a body moving slowly along the anisotropy axis. Thus in steady motions, odd viscosity acts to suppress variations of liquid velocity in a direction parallel to the anisotropy axis, inhibiting vortex stretching and vortex twisting. In unsteady and nonlinear motions, odd viscosity enhances the vorticity along the same axis, thus affecting both vortex stretching and vortex twisting.

Taylor halos and Taylor spears in odd viscous liquids

A body placed in a rigidly rotating fluid becomes circumscribed by a fictitious cylinder with generators parallel to the axis of rotation, a Taylor column. Slowly moving liquid impinging on the body will swerve around the cylinder. Thus, Taylor columns may form when a breeze impinges on a mountain or when slowly moving oceanic water impinges on a seamount, both due to the Earth's rotation. Here, we show that classical non-rotating liquids endowed with an odd or Hall coefficient of viscosity, exhibiting nondissipative behavior, also give rise to Taylor column structures resembling halos or spears. Steady three-dimensional flow of such a liquid becomes effectively two dimensional, swirling around the Taylor column imitating its rigidly rotating counterparts. Formation of Taylor halos and spears is attributed to the propagation of data along characteristics that may be parallel or oblique to a center axis, respectively.

Flow past a sphere translating along the axis of a rotating fluid: revisiting numerically Maxworthy's experiments

We compute the flow induced by the steady translation of a rigid sphere along the axis of a large cylindrical container filled with a low-viscosity fluid set in rigid-body rotation, the sphere being constrained to spin at the same rate as the undisturbed fluid. The parameter range covered by the simulations is similar to that explored experimentally by Maxworthy (J. Fluid Mech., vol. 40, 1970, pp. 453–479). We describe the salient features of the flow, especially the internal characteristics of the Taylor columns that form ahead of and behind the body and the inertial wave pattern, and determine the drag and torque acting on the sphere. Torque variations are found to obey two markedly different laws under rapid- and slow-rotation conditions. The corresponding scaling laws are predicted by examining the dominant balances governing the axial vorticity distribution in the body vicinity. Results for the drag agree well with the semi-empirical law proposed for inertialess regimes by Tanzosh & Stone (J. Fluid Mech., vol. 275, 1994, pp. 225–256). This law is found to apply even in regimes where inertial effects are large, provided that rotation effects are also large enough. Influence of axial confinement is shown to increase dramatically the drag in rapidly rotating configurations, and the container length has to be approximately a thousand times larger than the sphere for this influence to become negligibly small. The reported simulations establish that this confinement effect is at the origin of the long-standing discrepancy existing between Maxworthy's results and theoretical predictions.

Hidden Depths: A Unique Biodiversity Oasis in the Persian Gulf in Need of Further Exploration and Conservation

The Persian Gulf, a young and shallow epicontinental sea, is known for its unique geological and oceanographic characteristics that foster its diverse and productive marine ecosystems. A substantial portion of the Gulf’s seafloor consists of unconsolidated soft sediments, making it unsuitable for colonization by many sessile organisms. Consequently, relatively few hard grounds and submerged banks provide suitable habitats for benthic and substrate dwellers. This study documents a unique marine habitat on an offshore submerged bank, likely a raised salt dome, south of Qeshm Island, Iran. This area is home to a high concentration of ahermatypic coral species and remains relatively sheltered from human activities. The bank’s geographic location allows inflow currents from the Strait of Hormuz to transport larvae and nutrients, providing suitable substrates for various sessile invertebrates. Moreover, it causes the formation of Taylor columns, which affect fluid dynamics and circulation patterns, indirectly enhancing biodiversity. Despite facing risks from large-scale regional and localized threats, the bank’s remoteness from the main coast and its depth provide some protection. This study emphasizes the need for continued exploration and the implementation of effective conservation measures in the region, along with additional research to clarify the ecological and physical parameters supporting its diversity. It also presents the first in situ photographic evidence for the occurrence of some octocoral genera in the Gulf. Future research should investigate how the species compositions of hidden banks and shoals contribute to the overall biodiversity of the Persian Gulf.

Zapiola Gyre, Velocities and Mixing, New Argo Insights

AbstractThe Zapiola Gyre is a large, full‐depth, bottom‐intensified, anticyclonic recirculation in the Argentine Basin. It rotates around the Zapiola Drift, a sedimentary rise standing a few hundred meters above the abyssal plain, tall enough to create closed contours of planetary potential vorticity. Hence the gyre has been posited to be an eddy‐driven free mode that is damped primarily by the bottom Ekman layer. It describes approximately a zonally elongated ellipse with a zonal semi‐major axis of ∼440 km and a meridional semi‐minor axis of ∼125 km. Its volume transport is estimated here at ∼110 (±25) × 106 m3 s−1. It has peak depth‐averaged meridional velocities of ∼0.06 and ∼0.08 m s−1, and peak depth‐averaged zonal velocities of ∼0.11 and ∼0.12 m s−1. Peak surface velocities are ∼57% of peak bottom velocities, consistent with the dynamics of a bottom‐intensified Taylor column in a stratified flow. Deep and Core Argo float trajectories follow the gyre, with a couple of Core Argo floats with 1000‐dbar parking depths executing more than three anticyclonic rotations around it, and Core Argo floats that approach within ∼75 km of the gyre center executing on average ∼1.7 circumnavigations. Deep Argo temperature‐salinity profiles combined with historical shipboard CTD profile data afford maps newly illuminating the advective swirling of water‐mass signatures around the gyre at the density of the North Atlantic Deep Water salinity maximum. Their patterns are consistent with a Peclet number of ∼30 estimated here using previously published lateral eddy diffusivities in the region.

Summer Hydrography and Circulation in Storfjorden, Svalbard, Following a Record Low Winter Sea‐Ice Extent in the Barents Sea

AbstractStorfjorden, Svalbard, hosts a polynya in winter and is an important source region of Brine‐enriched Shelf Water (BSW) that, if dense enough, feeds the Arctic Ocean deep water reservoir. Changes in the BSW production may thus have far‐reaching impacts. We analyze the water mass distribution and circulation in Storfjorden and the trough south of it, Storfjordrenna, using hydrographic sections occupied in July 2016, following a winter characterized by the lowest ice coverage recorded in the Barents Sea. These observations reveal an unusual hydrographic state, characterized at the surface by the near absence of Melt Water and Storfjorden Surface Water, replaced by a saltier water mass. At depth, BSW (maximum salinity of 34.95) was found from the bottom up to 90 m, above the 120‐m deep sill at the mouth to Storfjordrenna. However, no gravity driven overflow was observed downstream of the sill: the dome of BSW remained locked over the depression in a cyclonic circulation pattern consistent with a stratified Taylor column. Observations further reveal a previously unreported intrusion of Atlantic Water (AW) far into the fjord, promoting isopycnal mixing with entrapped Arctic Water. This intrusion was possibly favored by positive wind stress curl anomalies over Svalbardbanken and Storfjordrenna. The bottom plume exiting Storfjordrenna was weak, carrying Polar Front Water rather than BSW, too light to sink underneath the AW layer at Fram Strait. Whether Storfjorden switched durably to a new hydrographic state, following the observed Atlantification of the Barents Sea after 2005, remains to be established.

The effect of rotating fluid with Taylor column on forced convective heat transfer

Taylor column phenomenon is a highly interesting flow-feature which is the result of Coriolis and inertia forces and can play a crucial role in modulating heat transfer characteristics. However, there is not much progress to capture Taylor column phenomenon numerically, let alone to study its heat transfer characteristics. In this regard, we have investigated the translation of a uniformly heated sphere through a rotating incompressible viscous fluid. The associated energy equation in axially symmetric spherical polar co-ordinates is solved using the Higher-Order Compact Scheme (HOCS) of the order four for steady high Reynolds number (Re) flow. It is noticed that the presence of Taylor column delays the rate of heat transfer past the sphere in the upstream zone while enhancing it in the downstream zone. The presence of the Taylor column at higher values of inverse Rossby number (1/Ro) modifies heat transfer in a typical manner over the cross-section of the sphere. A comparative study made between low Re heat transfer and steady high Re heat transfer unveils a broad perspective into the flow-physics of the problem.

Transition to three-dimensional flow in thermal convection with spanwise rotation

Convection in a frame of reference rotating rapidly about an axis perpendicular to the direction of gravity is a model system for convection in the equatorial region of gaseous planets and is realized in recent laboratory experiments. It is found that the transition from rotationally constrained two-dimensional to three-dimensional flows in this system does not occur at some fixed Rossby number. Instead, the Rossby number at the transition depends on the Reynolds number of the flow. The transition occurs when the Taylor columns which constitute the two-dimensional flow become unstable to elliptical instability.

Stewartson layer instability and triadic resonances in rotating sphere with oscillating inner core

This work is devoted to an experimental study of the stability of a steady flow in a rotating spherical cavity with an oscillating core. The case of circular core oscillations in a plane perpendicular to the rotation axis is considered. The steady flow structure strongly depends on the dimensionless oscillation frequency. In the frequency range where there are no inertial waves, the flow resembles a classical Taylor column with an almost uniform distribution of the angular velocity. With an increase in the oscillation amplitude above a certain threshold level, a two-dimensional azimuthal wave is excited at the column boundary. The wave velocity is determined by the intensity of the liquid differential rotation and does not depend on the Ekman number. In the case of oscillation with a frequency less than twice the rotation rate, the inertial waves propagate in fluid bulk and introduce a significant correction to the steady velocity profile. At high amplitudes, the triadic subharmonic resonance of inertial waves is excited. The triadic interactions simultaneously manifest themselves in two regions of the spherical shell, generating secondary waves with the same frequencies, but different wavenumbers: subharmonic waves with shorter (respectively, longer) wavelengths are observed in outer (respectively, inner) regions of the shell. In some cases, the third (intermediate) region with subharmonic waves of intermediate wavelength can be observed. The development of the triadic resonance leads to a strongly nonlinear response in the form of a system of steady vortices with well-defined azimuthal periodicity.

On the Intermittent Occurrence of Open‐Ocean Polynyas in a Multi‐Century High‐Resolution Preindustrial Earth System Model Simulation

AbstractA 500‐year‐long high‐resolution Community Earth System Model simulation under preindustrial radiative forcing produces Maud Rise Polynyas (MRPs) and Weddell Sea Polynya (WSP) events intermittently from decadal (MRP) to multidecadal (WSP) timescales. This periodicity is correlated with the variation of a regional Southern Annular Mode (SAM) index (evaluated regionally instead of circum‐Antarctic) with corresponding variations of precipitation and winds over the Weddell Sea. A negative index causes the upper‐ocean salinity to increase over multiple decades. Ultimately, brine rejection during seasonal sea‐ice formation superimposed on the multidecadal increase raises the upper‐ocean salinity beyond the tipping point for triggering deep convection that leads to polynyas. The initiation of polynya events is thus controlled by surface properties while the location of initiation is determined by bathymetric features. The persistent Taylor column effect, which is well represented by the high‐resolution model topography of the Maud Rise seamount, preconditions this region for MRP initiation. Therefore, MRPs form more frequently than WSPs in the simulation. When the upper‐ocean salinity is high, deep convection in the MRP region tends to be stronger, in which case MRPs are also more likely to grow into WSPs. Once WSPs emerge, they affect the regional atmospheric circulation and associated variables. We propose a regional coupled ocean‐atmosphere mechanism to explain both the periodic emergence of polynyas and the periodic variation of the regional SAM index. Although the temperature and salinity of Weddell Deep Water show upward trends due to model drift, these density‐compensating changes do not affect the frequency of polynya formation.

Exploring Ocean Circulation on Icy Moons Heated From Below

AbstractWe numerically explore convection and general circulation of an ocean, encased in a spherical shell of uniform thickness, heated from below by a spatially uniform heat flux, and whose temperature at the upper surface is relaxed to the freezing point of water. The role of salt is not considered. We describe the phenomenology and equilibrium solutions across a broad range of two key non‐dimensional numbers: the natural Rossby number, a measure of the influence of rotation, and the ratio of inner to outer radius of the moon's ocean, a measure of the geometry of the moon's tangent cylinder. Two distinct regimes of circulation are identified, both dominated by Taylor columns aligned with the rotation axis—“plumes” and “rolls” which predominate inside and outside the tangent cylinder, respectively. Inside the tangent cylinder, convective plumes align with Taylor columns that extend from the bottom to the ice shell. The plumes energize geostrophic turbulence which in turn generates a general circulation consisting counter‐rotating zonal jets. Moreover, the plumes are efficient at transferring heat from the bottom to the surface, resulting in loss of heat from the ocean to the polar ice. If the plumes are suppressed rolls outside the tangent cylinder become the dominant mode of heat transfer resulting in equatorial cooling. We conclude that if moons such as Enceladus and Europa were to be predominantly heated from below, they will likely have a “Jovian‐like” circulation: an unstratified, turbulent, geostrophically controlled ocean with strong “Taylor column” behavior and a circulation dominated by counter‐rotating zonal jets.

Phytoplankton biomass and photophysiology at the sub-Antarctic Prince Edward Islands ecosystem in the Southern Ocean

At the sub-Antarctic Prince Edward Islands (PEIs), a diverse ecosystem is supported by enhanced phytoplankton biomass levels, commonly referred to as the island mass effect. Phytoplankton responses to varied environmental conditions during austral summer (December 2008) and autumn (April–May 2013–2018) cruises were characterised by both surface and subsurface chlorophyll a (chla) maxima. While subsurface chla maxima were generally near the base of the upper mixed layer (z uml ) during the summer cruise, such maxima were located well below z uml during autumn cruises. Non-photochemical quenching resulted in severe underestimation of surface in situ chla. Substantially low F v /F m and σ PSII in the surface layers during December 2008 confirmed the photoinhibitory effects of high light exposure during the day and suggested damage to phytoplankton photosystem II reaction centres. Physiological measurements revealed that phytoplankton communities were probably not limited by nitrate or iron. However, some nutrient stress may have resulted from low surface silicates, which showed comparatively more daytime depletion during December 2008 than April–May 2013–2015. While the spatial distribution of in situ phytoplankton biomass during December 2008 was reminiscent of the island mass effect, congruent satellite observations surprisingly revealed that chla in the open ocean surrounding the PEIs was in fact much higher than chla on the island shelf. Our findings suggested that upwelling and retention, and consequent phytoplankton biomass accumulation, usually associated with a Taylor column structure at the PEIs may have been disrupted by enhanced offshore advection stemming from the interaction of mesoscale eddies and fronts with the PEI shelf. However, more detailed investigations are required to properly understand the spatial and temporal variations of phytoplankton biomass and their physiological responses to environmental fluctuations. • Surface and subsurface chlorophyll a maxima were observed in summer and autumn. • In December 2008, these maxima were located near the base of the upper mixed layer. • During autumn 2013–2018, such maxima were well below the upper mixed layer. • Several daytime profiles were compromised by non-photochemical quenching. • Photophysiological parameters confirmed effects of daytime high light exposure.

Dynamic Europa ocean shows transient Taylor columns and convection driven by ice melting and salinity

The deep (~100 km) ocean of Europa, Jupiter’s moon, covered by a thick icy shell, is one of the most probable places in the solar system to find extraterrestrial life. Yet, its ocean dynamics and its interaction with the ice cover have received little attention. Previous studies suggested that Europa’s ocean is turbulent using a global model and taking into account non-hydrostatic effects and the full Coriolis force. Here we add critical elements, including consistent top and bottom heating boundary conditions and the effects of icy shell melting and freezing on ocean salinity. We find weak stratification that is dominated by salinity variations. The ocean exhibits strong transient convection, eddies, and zonal jets. Transient motions organize in Taylor columns parallel to Europa’s axis of rotation, are static inside of the tangent cylinder and propagate equatorward outside the cylinder. The meridional oceanic heat transport is intense enough to result in a nearly uniform ice thickness, that is expected to be observable in future missions.

Force balance in rapidly rotating Rayleigh-Bénard convection.

The force balance of rotating Rayleigh-Bénard convection regimes is investigated using direct numerical simulation on a laterally periodic domain, vertically bounded by no-slip walls. We provide a comprehensive view of the interplay between governing forces both in the bulk and near the walls. We observe, as in other prior studies, regimes of cells, convective Taylor columns, plumes, large-scale vortices (LSVs) and rotation-affected convection. Regimes of rapidly rotating convection are dominated by geostrophy, the balance between Coriolis and pressure-gradient forces. The higher-order interplay between inertial, viscous and buoyancy forces defines a subdominant balance that distinguishes the geostrophic states. It consists of viscous and buoyancy forces for cells and columns, inertial, viscous and buoyancy forces for plumes, and inertial forces for LSVs. In rotation-affected convection, inertial and pressure-gradient forces constitute the dominant balance; Coriolis, viscous and buoyancy forces form the subdominant balance. Near the walls, in geostrophic regimes, force magnitudes are larger than in the bulk; buoyancy contributes little to the subdominant balance of cells, columns and plumes. Increased force magnitudes denote increased ageostrophy near the walls. Nonetheless, the flow is geostrophic as the bulk. Inertia becomes increasingly more important compared to the bulk, and enters the subdominant balance of columns. As the bulk, the near-wall flow loses rotational constraint in rotation-affected convection. Consequently, kinetic boundary layers deviate from the expected behaviour from linear Ekman boundary layer theory. Our findings elucidate the dynamical balances of rotating thermal convection under realistic top/bottom boundary conditions, relevant to laboratory settings and large-scale natural flows.

Velocimetry in rapidly rotating convection: Spatial correlations, flow structures and length scales (a) (a)Contribution to the Focus Issue Turbulent Thermal Convection edited by Mahendra Verma and Jörg Schumacher.

Rotating Rayleigh-Bénard convection is an oft-employed model system to evaluate the interplay of buoyant forcing and Coriolis forces due to rotation, an eminently relevant interaction of dynamical effects found in many geophysical and astrophysical flows. These flows display extreme values of the governing parameters: large Rayleigh numbers Ra, quantifying the strength of thermal forcing, and small Ekman numbers E, a parameter inversely proportional to the rotation rate. This leads to the dominant geostrophic balance of forces in the flow between pressure gradient and Coriolis force. The so-called geostrophic regime of rotating convection is difficult to study with laboratory experiments and numerical simulations given the requirements to attain simultaneously large Ra values and small values of E. Here, we use flow measurements using stereoscopic particle image velocimetry in a large-scale rotating convection apparatus in a horizontal plane at mid-height to study the rich flow phenomenology of the geostrophic regime of rotating convection. We quantify the horizontal length scales of the flow using spatial correlations of vertical velocity and vertical vorticity, reproducing features of the convective Taylor columns and plumes flow states both part of the geostrophic regime. Additionally, we find in this horizontal plane an organisation into a quadrupolar vortex at higher Rayleigh numbers starting from the plumes state.

Influence of magnetic field in the control of Taylor column phenomenon in the translation of a sphere in a rotating fluid

A numerical investigation has been performed to capture how the magnetic field interferes with Taylor column—a spectacular phenomenon occurring as a result of the Coriolis effect. In this pursuit, at first, we have considered the incompressible flow past a translating sphere in a rotating viscous fluid. This setup allows us to capture the Taylor column in the upstream region at critical values of inverse Rossby number (1/Ro) along with the subsequent formation of a cyclonic vortex in the downstream region as 1/Ro is increased. However, flow separation of any kind is considered to be an undesirable flow feature from industrial perspectives. We found that an application of magnetic field aligned with the motion of the sphere induces Lorentz force into the flow field that suppresses the Taylor column for lower values of 1/Ro, and, it dissolves the cyclonic vortex formed at higher values of 1/Ro. The strength of the Coriolis and Lorentz forces, their mutual interaction, and the value of inverse Rossby number determines the growth and decay of the Taylor column and the cyclonic vortex, thereby, regulating the ultimate nature of the flow.

On the numerical capture of Taylor column phenomena in rotating viscous fluid

Over the years, a number of researchers have explored the possibilities of capturing the fantastic Taylor column phenomena numerically. However, comprehensive satisfactory numerical results have not been obtained in spite of the presence of well established experimental and theoretical data. One important blockade in the process is that the existing lower-order schemes cannot capture the phenomena appropriately owing to the complexity of the flow which arises due to the effect of several parameters and nonlinearities. Hence we propose to use the Higher Order Compact Scheme (HOCS) to capture the Taylor column phenomena along with all its essential features. The results obtained using HOCS are found to be in line with available experimental results in the literature. The physical analysis of streamlines, swirl velocity, surface pressure, and pressure gradient show that there arises a reverse flow near the front and a cyclonic vortex near the rear stagnation point along with a geostrophic region under certain conditions depending on the balance between the Coriolis force and the pressure gradient.