Narrow Results

The turbulence in incompressible fluid is represented as a field theory in 3 dimensions. There is no time involved, so this is intended to describe stationary limit of the Hopf functional. The basic fields are Clebsch variables defined modulo gauge transformations (symplectomorphisms). Explicit formulas for gauge invariant Clebsch measure in space of generalized Beltrami flow compatible with steady energy flow are presented. We introduce a concept of Clebsch confinement related to unbroken gauge invariance and study Clebsch instantons: singular vorticity sheets with nontrivial helicity. This is realization of the “instantons and intermittency” program we started back in the 1990s.¹ These singular solutions are involved in enhancing infinitesimal random forces at remote boundary leading to critical phenomena. In the Euler equation vorticity is concentrated along the random self-avoiding surface, with tangent components proportional to the delta function of normal distance. Viscosity in Navier–Stokes equation smears this delta function to the Gaussian with width $h\propto {\nu }^{3/5}$ at $\nu \to 0$ with fixed energy flow. These instantons dominate the enstrophy in dissipation as well as the PDF for velocity circulation ${\mathrm{\Gamma }}_C$ around fixed loop $C$ in space. At large loops, the resulting symmetric exponential distribution perfectly fits the numerical simulations² including pre-exponential factor $1/\sqrt{\left|\mathrm{\Gamma }\right|}$. At small loops, we advocate relation of resulting random self-avoiding surface theory with multi-fractal scaling laws observed in numerical simulations. These laws are explained as a result of fluctuating internal metric (Liouville field). The curve of anomalous dimensions $\zeta (n)$ can be fitted at small $n$ to the parabola, coming from the Liouville theory with two parameters $\alpha$, $Q$. At large $n$ the ratios of the subsequent moments in our theory grow linearly with the size of the loop, which corresponds to finite value of $\zeta (\infty )$ in agreement with DNS.

Based on the wind turbine's complex wake vortex system and combining with the wind machine's aerodynamic performances, a hybrid method to design the wind turbine rotor, which discards the constant circulation along the wind rotor blade axis and embraces the airfoil's lift-drag characteristics, is presented. And the validity of the method is also proven by designing and computing a wind rotor.

The dynamics of Bose–Einstein condensates in a one-dimensional ring optical lattice is related to the interplay of the open system conditions and the initial atomic distribution. The circulation evaluation model based on the relative atomic density on each site is established to analyze the circulation strength under low dissipation. The direction of the circulation due to the symmetry breaking can be manipulated by changing the primary atomic distribution and the number of lattice sites. The effect of the atomic interaction on the atom flow in the optical ring lattice is analyzed to maintain the current interval rotation behavior.

A three dimensional baroclinic numerical model which consists of hydrodynamic, transport and turbulence model components, has been applied to two test cases, including: the wind induced flow in a laboratory basin and tidal flow in a model rectangular harbor. The agreement between the physical and numerical model results is highly encouraging. Model has been implemented to Ölüdeniz Lagoon located at the Mediterranean coast of Turkey to simulate tidal and wind driven currents. M2 tide is the dominant tidal constituent for the area. There exist some field measurements performed on water salinity, water temperature and current pattern in Ölüdeniz Lagoon. Even though measurements provide only some preliminary data for the site, favorable results have been obtained from the application of the model to a real coastal water body.

Fine scale eddies and circulation features in the ocean govern many small and large-scale processes, which get modulated due to small-scale horizontal variations in density. Some of these phenomena are responsible for nutrient upwelling, while some have implications on acoustic propagation. Three-dimensional observations at such a fine scale (∼ < 1 km) are hard to obtain in continuity from in-situ or satellite measurements. Numerical models of the ocean provide an opportunity to simulate the small-scale features of the oceanic circulation. In this study, we present a very high-resolution model for the ocean surrounding Vishakhapatnam (Vizag) region at the East Coast of India. The objective is to test and evaluate the configuration that has been prepared for this domain and then to nest/couple it within a larger/coarser domain model. We have made use of the Massachusetts Institute of Technology general circulation model (MITgcm) for this study. Open boundary conditions are prescribed from a regional ocean model for the Indian Ocean (IO) Region. The model is forced with ERA-interim winds and fluxes for a period of around 40 days. Ocean surface currents simulated from the model are compared with the Nucleus for European Modelling of the Ocean (NEMO) observations as well as from the outputs of the larger domain IO model

The support offered to tertiary education by the general books collection for circulation of a department's library is very significant, especially at the undergraduate level. In this research, we monitored the book loans in a department of Nutrition-Dietetics, in Greece, for the year 2009. The book titles loaned for a year were classified by subjects and the data were compared with the undergraduate syllabus of the department, to conclude on the teaching support these books offered. The results indicated that most of the books circulated in the library concerned tables of food composition, dietetics handbooks, and biochemistry-physiology books. On the other hand, the number of book titles loaned to students within 2009 was limited compared with those offered for loan. Our results show the need for close cooperation between librarians and tertiary education teachers in library management as well as the need for constant monitoring of the students changing needs.

The dynamics which control the spread of tracers in the N.W. European Shelf Seas are reviewed. The perspective of this review is to allow a comparison with the vastly different regimes found in Australian waters. Whilst these N.W. European Shelf Seas are dominated by the influence of the M₂ semi-diurnal tide, the Gulfs off South Australia have significant diurnal constitutents and a peculiar near equality of M₂ and S₂—producing ‘dodge’ tides. Nevertheless, generalised expressions for both the annual mean and the seasonal amplitude of sea surface temperature (derived from North Atlantic data) are generally applicable.

The greater sensitivity of diurnal tidal constituents to bed friction coupled with the proximity to the related inertial latitude suggests that tidal propagation models may require more tuning of the bed stress coefficient. However the greatest contrast is for ‘estuaries’ where the excess of evaporation over precipitation and river flow produces ‘inverse estuaries’ unknown in Europe. Whilst flushing time concepts can be used in similar fashions, the extraction of tracers from such estuaries occurs close to the bed via ‘inverse’ salt wedges. This contrast with mean surface extraction in European estuaries will have significant influences on the related ecology.

A ‘Future Work’ section describes recent developments and plans to extend marine forecasting via Operational Oceanography. Whilst Australian requirements will differ considerably, the need to maintain awareness and adopt common practices is important to fulfill the wider goals of GOOS—the Global Ocean Observing System.

In this paper, a basic principle of multiple inverters parallel control is introduced and parallel inverters circulation phenomenon of Micro-grids is analyzed. Since the conventional droop control algorithm is full of flaw, a new kind of droop control strategy is put forward to improve the unequal distribution of power by adjusting the droop parameters. The simulation results show that synchronous voltage source control based on the droop characteristic curve can make the power inflection of the micro source apportionment system, which also can share frequency and voltage regulation of the system to maintain the system stability.