Oceanic Motions Research Articles

Scaling analysis of the thermal hydraulic behavior in the secondary side of steam generator

Steam generator is one of the key facilities in nuclear power plant. Due to its complex structure and huge volume, the experimental and numerical research of steam generator needs a large amount of costs and computational resources. One feasible method is to replace the prototype steam generator with a model by the scaling analysis. In this work, a systematical scaling analysis for the thermal hydraulic phenomenon in the secondary side of steam generator in ocean motions is carried out. The scaling analysis is decomposed into three processes, natural circulation, forced convection and lateral flow. A series of scaling criteria are obtained. It is found that the similarity of heat transfer could be achieved by adjusting the parameters of the primary side. It is also revealed that the conventional scaling method could not guarantee the similarity of transverse flow due to the improper similarity of lateral resistance. Besides that, the scaling criteria for the amplitude and period are also obtained, which could be used in the subsequent experiments and numerical simulation.

MARINA DISTRICT DEVELOPMENT COMPANY LLC., DOING BUSINESS AS BORGATA HOTEL CASINO & SPA V. AC OCEAN WALK LLC, DOING BUSINESS AS OCEAN CASINO RESORT

MARINA DISTRICT DEVELOPMENT COMPANY LLC., DOING BUSINESS AS BORGATA HOTEL CASINO & SPA V. AC OCEAN WALK LLC, DOING BUSINESS AS OCEAN CASINO RESORT

Solitonic interactions for Rossby waves with the influence of Coriolis parameters

In the current study, the Rossby waves envelope near the equator is studied starting from a potential vorticity equation with the horizontal component of Coriolis parameter. Based on the equation, we first establish the amplitude evolution equation of the Rossby waves with complete Coriolis parameter and obtain rational function solutions by means of the subsidiary ordinary differential equation method with the help of chirp-free hypothesis. Then the 1-, 2-, 3-and N-soliton solutions are also obtained by the Hirota method. For these obtained solutions, they are rarely mentioned in fluid mechanics of ocean and atmospheric motion. On the other hand, these three-dimensional stereograms of the 1-, 2-soliton solutions are depicted with the physical parameter changing. The influence of each parameter on wave amplitude, the peak position and propagation direction of Rossby waves are discussed. The results show that the horizontal Coriolis parameter only alter the phase shift of the Rossby waves amplitude for the 1-soliton and 2-soliton solution. These results are of great significance for further theoretical research in geophysical fluid.

Testing a Novel Aggregated Methodology to Assess Hydrodynamic Impacts on a High-Resolution Marine Turtle Trajectory

We designed a novel aggregated methodology to infer the impact of ocean motions on the movements of satellite-tracked marine turtles adopting available oceanographic observations and validated products of a numerical oceanographic forecasting system. The method was tested on an 11-months trajectory of a juvenile loggerhead turtle (LT) wandering in the Tyrrhenian Sea (Mediterranean Sea) that was reconstructed with a high-resolution GPS tracking system. The application of ad-hoc designed metrics revealed that the turtle’s route shape, ground speed and periodicities of its explained variance mimic the inertial motions of the sea, showing that this methodology is able to reveal important details on the relation between turtle movements and oceanographic features. Inertial motions were also identified in the observed trajectory of a surface drifting buoy sampling the Tyrrhenian Sea in a common period. At each sampling point of the turtle trajectory, the sea current eddy kinetic energy (EKE) and a Sea Current Impact index were computed from a validated set of high-resolution ocean modeling products and their analysis showed the relevant effects of the highly variable local sea currents mechanical action. Specifically, the metric we adopted revealed that the turtle trajectory was favorably impacted by the encountered sea current advection for about 70% of its length. The presented oceanographic techniques in conjunction with high-resolution tracking system provide a practicable approach to study marine turtle movements, leading the way to discover further insights on turtle behavior in the ocean.

Spaceborne infrared imagery for early detection of Weddell Polynya opening

Abstract. Knowing when sea ice will open is crucial, notably for scientific deployments. This was particularly obvious when the Weddell Polynya, a large opening in the winter Southern Ocean sea ice, unexpectedly re-appeared in 2016. As no precursor had been detected, observations were limited to chance autonomous sensors, and the exact cause of the opening could not be determined accurately. We investigate here whether the signature of the vertical ocean motions or that of the leads, which ultimately re-open the polynya, are detectable in spaceborne infrared temperature before the polynya opens. From the full historical sea ice concentration record, we find 30 polynyas starting from 1980. Then, using the full time series of the spaceborne infrared Advanced Very High Resolution Radiometer, we determine that these events can be detected in the 2 weeks before the polynya opens as a reduction in the variance of the data. For the three commonly used infrared brightness temperature bands, the 15 d sum and 15 d standard deviation of their area median and maximum are systematically lower than the climatology when a polynya will open. Moreover, by comparing the infrared brightness temperature to atmospheric reanalysis, hydrographic mooring data, and autonomous profilers, we find that temporal oscillations in one band and the decrease in the difference between bands may be used as proxies for upwelling of warm water and presence of leads, respectively, albeit with caution. Therefore, although infrared data are strongly limited by their horizontal resolution and sensitivity to clouds, they could be used for studying ocean or atmosphere preconditioning of polynyas in the historical record.

On dynamically unresolved oceanic mesoscale motions

Abstract

Mechanical Metamaterials Gyro-Structure Piezoelectric Nanogenerators for Energy Harvesting under Quasi-Static Excitations in Ocean Engineering.

In this study, we develop the mechanical metamaterial-enabled piezoelectric nanogenerators in the gyro-structure, which is reported as a novel green energy solution to generate electrical power under quasi-static excitations (i.e., <1 Hz) such as in the ocean environment. The plate-like mechanical metamaterials are designed with a hexagonal corrugation to improve their mechanical characteristics (i.e., effective bending stiffnesses), and the piezoelectric trips are bonded to the metaplates. The piezo-metaplates are placed in the sliding cells to obtain the post-buckling response for energy harvesting under low-frequency ocean motions. The corrugated mechanical metamaterials are fabricated using the three-dimensional additive manufacturing technique and are bonded with polyvinylidene fluoride strips, and the nanogenerator samples are investigated under the quasi-static loading. Theoretical and numerical models are developed to obtain the electrical power, and satisfactory agreements are observed. Optimization is conducted to maximize the generated electrical power with respect to the geometric consideration (i.e., changing the corrugation pattern of the mechanical metamaterials) and the material consideration (i.e., changing the mechanical metamaterials to anisotropic). In the end, we consider the piezoelectric nanogenerators as a potential green solution for the energy issues in other fields.

Algorithmic Improvements to Finding Approximately Neutral Surfaces

AbstractInterior oceanic motions occur predominantly along, rather than across, the neutral tangent plane. These planes do not link together to form well‐defined surfaces, so oceanographers use approximately neutral surfaces. To date, the most accurate such surface is the ω‐surface, but its practical utility was limited because its numerical implementation was slow and sometimes unstable. This work upgrades the speed, robustness, and utility of ω‐surfaces. First, we switch from solving an overdetermined matrix problem by minimal least squares, to solving an exactly determined matrix problem, obtained either by the normal equations (multiplication by the matrix's transpose) or by discretizing Poisson's equation derived from the original optimization problem by the calculus of variations. This reduces the computational complexity, roughly from to , where N is the number of grid points in the surface. Second, we update the surface's vertical position by solving a nonlinear equation in each water column, rather than assuming the stratification is vertically uniform. This reduces the number of iterations required for convergence by an order of magnitude and eliminates the need for a damping factor that stabilized the original software. Additionally, we add “wetting” capacity, whereby incrops and outcrops are reincorporated into the surface should they become neutrally linked as iterations proceed. The new algorithm computes an ω‐surface in a 1,440 by 720 gridded ocean in roughly 15 s, down from roughly 11 h for the original software. We also provide two simple methods to label an ω‐surface with a (neutral) density value.

Power Oriented Design and Optimization of Dual Stator Linear-Rotary Generator With Halbach PM Array for Ocean Energy Conversion

In this paper, considering the oceanic multiple degree of freedom motion, a double stator linear-rotary permanent magnet (DSLRPM) generator with Halbach PM array is proposed for direct drive ocean energy conversion. It focuses on the power maximization generation resulting in a highly optimized DSLRPM generator to improve the generated power of the ocean energy conversion system in complex ocean condition. Based on the power-oriented design concept, the whole design process is divided into two steps. In the initial design procedure, the operating domain design is conducted, and the design point is selected. In the optimization design procedure, the non-dominated sorting genetic algorithm II (NSGA-II) coupled with response surface methodology (RSM) and sensitivity analysis is proposed to be as an optimization design technique. Finally, a prototype based on the optimized results is manufactured. The experimental results agree with the simulated result, and they both reveal that the proposed method can offer an effective design and optimization for the DSLRPM generator, where the multiple oceanic motions and complex operating conditions are considered.

The simulation research on the natural circulation operation characteristic of FNPP in rolling and inclined condition

Abstract Recently, the FNPP (Floating Nuclear Power Plant) has got more and more attention and rapid development due to very wide prospect application on remote areas or islands. In general, the IPWR (Integral Pressurized Water Reactor) is adopted to meet the requirements of the limited space, the nuclear safety and the maneuverability in marine. The IPWR could depend on natural circulation operation to remove the residual heat of core under accident or low load operation condition. Because the driving head is low, the natural circulation flow is likely to be influenced by rolling and inclined condition. To clarify the natural circulation flow characteristics of the core in FNPP rolling motion and inclined condition, based on the modified THEATRe code by adding the ocean motion module and spatial coordinate convert module, the main thermal-hydraulic parameters variation in rolling and inclined condition were obtained. The effect of inclined angle, rolling amplitude and period on the natural circulation flow were discussed. The natural circulation flow in the core fluctuates periodically with rolling motion. And the inclination and rolling will also cause the degree of steam superheat of OTSG secondary side fluctuate, which could impact on the stable operation of secondary side system.

Nonlinear hydromagnetic instability of oscillatory rotating rigid-fluid columns

The current paper is concerned with the nonlinear stability analysis of rotating magnetic fluid columns. The rotation sources are a mixture of both uniform and oscillating behavior. The motivation behind tackling this topic is the increasing interest in atmospheric and oceanic motions. The system consists of two magnetic phase fluid that fills two infinite vertical cylinders. An azimuthal uniform magnetic field is penetrated on the system. The governing equations of motion, in terms of the Coriolis force and reduced pressure, along with Maxwell’s equation in the quasi-static approximations are considered. Consequently, the disturbance of the interface has an azimuthal behavior. The fluids are fully saturated in porous media. In light of the implication of the nonlinear boundary conditions, the solutions of the linearized equations of motion resulted in a nonlinear characteristic dispersion equation. Utilizing the homotopy perturbation technique, this equation is analyzed. A modification of the latter equation is made to seem like a nonlinear Klein–Gordon equation. The stability criteria are realized in linear as well as nonlinear approaches. A set of diagrams is graphed to illustrate the effects of several non-dimensional numbers on the stability profile in resonance as well as non-resonance cases.

Seasonal and nodal variations of predominant tidal constituents in the global ocean

Tides are one of the basic types of ocean water motions. Previous studies have reported that the M2 constituent exhibits seasonal variations (annual cycles) in some regions. However, based on the newly proposed method of modified two-step harmonic analysis (HA) and its application at 240 global tide gauges, we find that the M2 constituent as well as the S2 and K1 do not have significant seasonal variations at these tide gauges. The seasonal variations of the M2 constituent reported in previous studies are caused by its satellites, the H1 and H2 constituents, which are not resolved in these studies due to the short time window (one month or three months) used in HA. Because the frequency of the H1 (H2) constituent is equal to that of the M2 minus (plus) the frequency of annual cycles, the superposition of the M2, H1 and H2 constituents with constant amplitudes is equivalent to the M2 constituent with seasonally varying amplitudes. Compared with the new method, some adaptations to traditional HA aiming to capture variations in amplitudes and phase lags of constituents have some limitations, because they either neglect some satellites of the major constitutes or introduce spurious fluctuations resulting from an unreasonably large number of independent points. The nodal modulations of predominant constituents are also explored in this study. On the global scale, the nodal modulations of the M2, K1 and O1 constituents agree with the theoretical predictions, except a cold spot region with reduced nodal modulation in the Gulf of Maine and a hot spot region with enhanced nodal modulation in the South China Sea for the M2. Nodal modulation is also found for the S2 constituent (in theory, the S2 has no nodal modulation), which is 0.8% averaged at 164 tide gauges where the S2 is not too weak.

RETRACTED ARTICLE: Ocean dynamic equations with the real gravity

Two different treatments in ocean dynamics are found between the gravity and pressure gradient force. Vertical component is 5–6 orders of magnitude larger than horizontal components for the pressure gradient force in large-scale motion, and for the gravity in any scale motion. The horizontal pressure gradient force is considered as a dominant force in oceanic motion from planetary to small scales. However, the horizontal gravity is omitted in oceanography completely. A non-dimensional C number (ratio between the horizontal gravity and the Coriolis force) is used to identify the importance of horizontal gravity in the ocean dynamics. Unexpectedly large C number with the global mean around 24 is obtained using the community datasets of the marine geoid height and ocean surface currents. New large-scale ocean dynamic equations with the real gravity are presented such as hydrostatic balance, geostrophic equilibrium, thermal wind, equipotential coordinate system, and vorticity equation.

Role of Cationic Size and Valency in Mechanoelectrical Transduction of Ion-Containing Polymers

The present article entails a novel phenomenon of mechanoelectrical transduction, viz., electricity generation driven by ionic polarization/depolarization in various ion-containing solid polymer electrolyte membranes (PEMs) undergoing cantilever flexure. These PEMs were photopolymerized via UV irradiation in the miscible state of binary mixtures of poly(ethylene glycol) diacrylate (PEGDA) polymer precursors and ionic salts containing cations of different sizes and valencies (i.e., Li⁺, K⁺, Mg²⁺, and Al³⁺), where the counter bis(trifluoromethanesulfonyl)imide (TFSI–) anion was kept invariant. The influence of the cation types on the ionically driven mechanoelectrical responses, viz., flexoelectricity, was investigated in relation to the ionic conductivity and mechanical and thermal characteristics of the PEMs, undergoing intermittent square-mode bending. Of particular interest is the observation of a systematic electrical response upon manipulation of the ionic valency/size ratio of the dissociated cations, i.e., a higher response was found in the case of a larger valency/size ratio. Additionally, mechanoelectrical energy conversion was estimated to increase with increasing cation valency/size ratio (viz., Al³⁺). Understanding the mechanoelectrical transduction behavior of the present ion-containing PEMs, referred to as flexoionic PEMs, will enable their utilization in sensing and clean energy-harvesting applications from the natural environment such as wind and oceanic wave motions.

Dynamical features of near-inertial motions in global ocean based on the GDP dataset from 2000 to 2019

Based on the latest oceanic surface drifter dataset from the global drifter program during 2000–2019, this study investigated the global variation of relative frequency shift (RFS), near-inertial energy (NIE) and inverse excess bandwidth (IEB) of near-inertial motions, and analyzed their relations with oceanic mesoscale dynamics, relative vorticity and strain. Compared with previous works, we have some new findings in this study: (1) the RFS was high with negative values in some regions in which we found a significant blue shift of the RFS in the equatorward of 30°N (S) and from 50°N to 60°N in the Pacific, and a red shift in the western boundary currents and their extension regions, the North Atlantic and the Antarctic Circumpolar Current regions; (2) more peak values of the NIE were found in global regions like the South Indian Ocean, the Luzon Strait and some areas of the South Ocean; (3) the global distribution of the IEB were characterized by clear zonal bands and affected by vorticity and wind field; (4) the RFS was elevated as the absolute value of the gradient of vorticity increased, the IEB did not depend on the gradient of vorticity, and the eddy kinetic energy (EKE) weakened with the decrease of the absolute value of RFS; (5) the NIE decreased with increasing absolute value of the relative vorticity and the gradient of vorticity, but it increased with increasing strain and EKE when EKE was larger than 0.003 2 m2/s2.

Theoretical analysis of equatorial near-inertial solitary waves under complete Coriolis parameters

An investigation of equatorial near-inertial wave dynamics under complete Coriolis parameters is performed in this paper. Starting from the basic model equations of oceanic motions, a Korteweg de Vries equation is derived to simulate the evolution of equatorial nonlinear near-inertial waves by using methods of scaling analysis and perturbation expansions under the equatorial beta plane approximation. Theoretical dynamic analysis is finished based on the obtained Korteweg de Vries equation, and the results show that the horizontal component of Coriolis parameters is of great importance to the propagation of equatorial nonlinear near-inertial solitary waves by modifying its dispersion relation and by interacting with the basic background flow.

Wave Energy Estimation based on the Statistical Analysis of the Significant Height and Periodicity

The study of wave potential at coastal points requires involving many parameters and degrees of freedom of ocean wave motion. In this work, we focus to the two most relevant ones: the wave’s significant height and its periodicity. By means of a descriptive statistical analysis of oceanographic databases from two coastal nodes in Mexico, we present realistic estimations of wave potentials. This work allows advancing the knowledge for the estimation of ocean wave energy potential and can be useful for future design of distributed generation plants based on this renewable alternative.

Diagnosing the Scale- and Space-Dependent Horizontal Eddy Diffusivity at the Global Surface Ocean

AbstractOceanic tracers are transported by oceanic motions of all scales, but only the large-scale motions are resolved by the present-day Earth system models. In these models, the unresolved lateral sub-gridscale tracer transport is generally parameterized through diffusive closures with a scale-independent diffusion coefficient. However, evidence from observations and theory suggests that diffusivity varies spatially and is length-scale dependent. Here we provide new scale-dependent quantification of the global surface diffusivities. To this end we use a recently developed statistical inversion method, MicroInverse, to diagnose horizontal surface diffusivities from observed sea surface temperature and idealized model simulation. We compare the results to theoretical estimates of mixing by the large-scale shear and by the sub-gridscale velocity fluctuations. The diagnosed diffusivity magnitude peaks in the tropics and western boundary currents with minima in the subtropical gyres (~3000 and ~100 m2 s−1) at ~40-km scale, respectively. Focusing on the 40–200-km length scale range, we find that the diffusivity magnitude scales with the length scale to a power n that is between 1.22 and 1.54 (90% confidence) in the tropics and also peaks at values above 1 in the boundary currents. In the midlatitudes we find that 0.58 &lt; n &lt; 0.87 (90% confidence). Comparison to the theory suggests that in regions with n &gt; 1 the horizontal mixing is dominated by large-scale shear, whereas in regions where n &lt; 1 the horizontal mixing is due to processes that are small compared to the 40–200-km length scale range considered in this study.

Multi-order Accurate Stabilized Tracking System with Multi-DOF under Influence of Ocean Waves

In order to avoid influence of ocean wave motion to the tracking system, a tracking platform with multi-DOF and multi-level accurate stabilized system is designed. The position of platform and load on multiple degrees of freedom can be compensated, so as to meet the required stability conditions and realize the stable tracking of the platform to the target. The stability of the platform is analyzed and simulated. The simulation results show that the control effect of the stable platform is good, and the stability effect of roll and heave of the platform is obvious, which can slide in two degrees of freedom at XY directions, with engineering application prospect.

Convergence Results on the Boundary Conditions for 2D Large-Scale Primitive Equations in Oceanic Dynamics

In this paper, the initial boundary value problem for the two-dimensional large-scale primitive equations of large-scale oceanic motion in geophysics is considered, which are fundamental models for weather prediction. By establishing rigorous a priori bounds with coefficients and deriving some useful inequalities, the convergence result for the boundary conditions is obtained.