Turbulence Power Research Articles

An evaluation of scintillation index in atmospheric turbulent for new super Lorentz vortex Gaussian beam

Super Lorentz vortex Gaussian beam (SLVGB) is propagated via the turbulent atmosphere parameters. The benefit key of the SLVGB wave model is that the unlimited bandwidth wave and a spherical wave are involved. Additionally, Huygens Fresnel integral was used for schoolwork to study the propagation of SLVGB in a slant direction via a moderate turbulent medium. On the other hand, applying the crude international telecommunication union (ITU-R) model possible. Moreover, the Kolmogorov turbulent power spectrum model is applied, and the source field is dispersed by the zenith angle to the receiver plane. Additionally, examine the contour of the source field and the SLVGB intensity. To investigate various parameters such as source size, mode, scintillation index, topological charge, and others that are associated with the beam of super Lorentz vortex Gaussian are entirely understood, the outcomes were examined, and obtained other references to build the beam of slant path propagation in turbulent; the form constants are especially in comparison and matching. Our graphical findings indicate that the parameters happened randomly in the scintillation index and intensity of the SLVGB, resulting in a novel beam technical configuration. To summarize, this article is advantageous for remote sensing and uses an optical communications system and laser applications.

Random process with a turbulent power spectrum

Random processes with large fluctuations are simulated by a system of nonlinear stochastic equations describing coupled nonequilibrium phase transitions. It is shown that under the action of white noise a critical state can arise, which is characterized by a turbulent spectrum and a scale-invariant probability density function. Under the action of a periodic force on a random process with a turbulent spectrum, a resonant response of scale-invariant functions arises. The lumped system is generalized to the spatially distributed case. To study the sustainability and stationarity of a random process, the principle of maximum entropy is used.

Cumulative generation of electricity from the wind of passing vehicles and natural wind in the Bukhara region of the Republic of Uzbekistan

Wind energy occupies are a rather important place in the balance of global “green” generation. Wind energy directly depends on the wind speed in the region under consideration. The highest average wind speed during the year is observed in the Bukhara region of the Republic of Uzbekistan. Vertical wind generators are widely used to collect the energy of natural wind and air movement generated by traffic into electricity. In order to effectively use the power of natural wind and air turbulence that occurs during the movement of vehicles, it is proposed to install vertical wind generators on the side of highways of international importance in the Bukhara region at certain intervals of the road.

Monitoring of Wind Effects on a Super-Tall Building under a Typhoon

Field measurements are critical to further understand the structural behavior of super-tall buildings under strong wind actions. This paper presents field measurements that reflect the wind characteristics and wind effects on Leatop Plaza under Typhoon Vicente. Wind field characteristics, including the turbulence intensity, gust factor, and power spectral density of wind speed in an urban area, were obtained on the basis of a statistical analysis of measured wind data. Subsequently, measured wind-induced accelerations were used to evaluate the dynamic characteristics of the building and the effects of wind on it. On the basis of the first several modes, the modal properties, i.e., the natural frequency and damping ratio, were identified via the fast Bayesian fast Fourier transform method and compared with those identified using the stochastic subspace method. The discrepancy between the identified results and finite element model predictions is presented and discussed. Finally, the variation in the modal parameters with respect to time and the vibration amplitude was analyzed while considering the associated posterior uncertainty.

Novel Simulation and Analysis of Mie-Scattering Lidar for Detecting Atmospheric Turbulence Based on Non-Kolmogorov Turbulence Power Spectrum Model.

The Mie-scattering lidar can detect atmospheric turbulence intensity by using the return signals of Gaussian beams at different heights. The power spectrum method and Zernike polynomial method are used to simulate the non-Kolmogorov turbulent phase plate, respectively, and the power spectrum method with faster running speed is selected for the subsequent simulation. In order to verify the possibility of detecting atmospheric turbulence by the Mie-scattering lidar, some numerical simulations are carried out. The power spectrum method is used to simulate the propagation of the Gaussian beam from the Mie-scattering lidar in a vertical path. The propagation characteristics of the Gaussian beam using a non-Kolmogorov turbulence model are obtained by analyzing the intensity distribution and spot drift effect. The simulation results show that the scintillation index of simulation is consistent with the theoretical value trend, and the accuracy is very high, indicating that the method of atmospheric turbulence detection using Mie-scattering lidar is effective. The simulation plays a guiding role for the subsequent experimental platform construction and equipment design.

The Vision of Global Maritime Fulcrum within ASEAN Centrality to Maintain Regional Stability

The purpose of this study is to discuss the vision of Global Maritime Fulcrum precisely for Indonesia’s foreign policy in the region. This study also in addition to examine the essential needs for coherence and collective response of ASEAN toward strategic rivalries US-China, then bring great risk in the vicinity, notably territorial disputes in South China Sea and following with the logical consequence of the Quad. By using the theory of Regional Security Complex by Barry Buzan, primary and secondary data related to Indonesia’s GMF in the regional architecture were processed using qualitative methods. This study also links the concept of dynamic equilibrium by Indonesia then-Foreign Minister, Marty Natalegawa, which emphasized trust and norms among all actors who were involved in the region, of which aligned with ASEAN centrality. The research result leads to the capability of Indonesia which implies if Indonesia is keen to improve its capabilities through the GMF, this vision can be considered as a tangible complementary and modality in the midst of emerging turbulence power in the region

Interpretation of Radio Wave Scintillation Observed through LOFAR Radio Telescopes

Abstract Radio waves propagating through a medium containing irregularities in the spatial distribution of the electron density develop fluctuations in their intensities and phases. In the case of radio waves emitted from astronomical objects, they propagate through electron density irregularities in the interstellar medium, the interplanetary medium, and Earth’s ionosphere. The LOFAR radio telescope, with stations across Europe, can measure intensity across the VHF radio band and thus intensity scintillation on the signals received from compact astronomical objects. Modeling intensity scintillation allows the estimate of various parameters of the propagation medium, for example, its drift velocity and its turbulent power spectrum. However, these estimates are based on the assumptions of ergodicity of the observed intensity fluctuations and, typically, of weak scattering. A case study of single-station LOFAR observations of the strong astronomical source Cassiopeia A in the VHF range is utilized to illustrate deviations from ergodicity, as well as the presence of both weak and strong scattering. Here it is demonstrated how these aspects can lead to misleading estimates of the propagation medium properties, for example, in the solar wind. This analysis provides a method to model errors in these estimates, which can be used in the characterization of both the interplanetary medium and Earth’s ionosphere. Although the discussion is limited to the case of the interplanetary medium and Earth’s ionosphere, its ideas are also applicable to the case of the interstellar medium.

Propagation characteristics of radial phase-locked discrete vector beam generated from a Gaussian Schell-Model laser array in atmospheric turbulence

In this paper, combining the advantages of partial coherence, vector beam, and laser array in better resistance to atmospheric turbulence, high capacity, and high output power, we proposed a radial phase-locked discrete vector beam generated from a Gaussian Schell-Model (GSM) laser array (i.e., phase-locked GSM discrete vector beam array) and theoretically studied its propagation characteristics in atmospheric turbulence. The analytical expressions for spectral intensity, spectral degree of coherence (DOC), and spectral degree of polarization (DOP) of a phase-locked GSM discrete vector beam array were derived based on the extended Huygens-Fresnel principle. And also, based on numerical simulation, we investigated the influence of atmospheric and laser parameters on the propagation properties in detail. The results show that the beam profile will gradually evolve from hollow structure distribution, then form a flat-topped beam and finally present the Gaussian-like distribution; the spectral DOC exhibits decaying oscillation analogous to under-damping vibration; a dip appears in the distribution of the spectral DOP. The evolution rate of spectral intensity, oscillation amplitude, and period of spectral DOC and dip width of spectral DOP are determined by propagation distance, refraction structure constant, beam waist, spatial correlation length, and the number of beamlets. More importantly, by analyzing Stokes parameters, different initial polarization distributions correspond to different crosslines of S1/S0, and even with the increase of the propagation distance, the crosslines of S1/S0 still show similar performance. This work may provide novel thoughts and methods to improve propagation performance and benefit potential applications in free-space optical communication.

A computational approach to estimate the flow and output parameters of various solar updraft tower plants and a proposed model for the best power output

ABSTRACT Three different models were developed to examine the flow and thermodynamic characteristics of the solar updraft tower (SUT) power plant and the best model is proposed. A step is taken to find the location of the turbine to absorb maximum kinetic energy. It is found that the maximum and average air velocities inside model-I were higher (3.06 and 1.63 ms−1, respectively) compared to model–II (2.4 and 1.34 ms−1) and model-III (2.9 and 1.57 ms−1). The maximum air temperature inside the model-II was higher (322 K). Turbulent kinetic energy, power produced and overall efficiency were the best in model–II than the other two models. The present outcomes were validated with the literature data and observed a good match.

Changes in orbital angular momentum distribution of a twisted partially coherent array beam in anisotropic turbulence.

Based on the generalized Huygens Fresnel integral, we derive the analytical formula of the cross-spectral density of a twisted partially coherent array beam propagating in non-Kolmogorov anisotropic turbulence, and investigate the changes in orbital angular momentum (OAM). The results show that the anisotropy of the turbulence causes different effects in horizontal and vertical directions. The spectral density distribution of twisted partially coherent array beam in turbulence presents self-splitting and rotation, which combines the interesting effects of the twist phase and coherent structure. Although OAM is conserved, the spatial distribution of OAM flux density can be changed by changing the propagation distance, power and anisotropy of turbulence, and the modulation of the twist phase affects not only the magnitude of OAM but also its distribution. Our work is helpful for exploring new forms of OAM sources, and promote the application of free-space optical communications and optical field modulation.

Public administration and politics meet turbulence: The search for robust governance responses

Public administration and politics meet turbulence: The search for robust governance responses

Power number and hydrodynamic characterization of a stirred vessel equipped with a Retreat-Blade Impeller and different types of pharmaceutical single baffles

• Vessels with single baffles are commonly found in pharmaceutical facilities. • The experimental Power Numbers (Po) for an RBI in single-baffle vessels were determined. • Results for beavertail, D-type, H-type, finger-type, fin-type baffles were obtained. • CFD predictions for Power Numbers were in good agreement with experiments. • A power-law correlation for Po vs. the area of the baffles in the liquid was derived. Many operations conducted in the pharmaceutical industry take place in glass-lined vessels provided with a Retreat-Blade Impeller (RBI) and one of different types of single baffles. Little information is available on the power dissipated by the RBI and on the hydrodynamic of such systems. Here, the turbulent Power Numbers, Po’s, for an RBI in a scaled-down vessel equipped with one of the different types of single baffles used in the pharmaceutical industry (beavertail, D-type, H-type, finger-type, fin-type baffles) were experimentally determined for different positions of the baffles and computationally obtained, together with the velocity distribution. Vortex formation, occurring with the beavertail baffle, was also quantified experimentally and computationally. The experimental Po values were in close agreement with the computational predictions. Additionally, a simple power-law correlation was established between Po and the dimensionless vertical cross-sectional area of the baffles, resulting in an equation with a good fit with the experimental data.

A nonlinear wave-based model to study the magnetic turbulence generation associated with the nonlinear evolution of Kinetic Alfven Wave in laser-produced plasma relevant to laboratory and astrophysical plasmas

A nonlinear wave-based model is introduced to understand the behaviour of the ion-scaled magnetic turbulence in the laser-produced plasmas generated during the high-intensity laser-plasma interaction. The coupled model equations are developed for the pump Kinetic Alfven Wave and the low-frequency Magnetosonic Wave by taking into account the ponderomotive nonlinearity. Numerical simulation is performed using the pseudo-spectral and the finite difference method to solve the model equations. The simulation results illustrate the nonlinear evolution of the pump wave at the early stage, which subsequently becomes turbulent. From the simulation results, the time-averaged turbulent power spectrum has been studied. The observed MHD type and KAW type plasma turbulence in different spatial scale lengths are nearly close to the magnetic turbulence reported in Chatterjee et al.12 experimental results. A semi-analytical method is also given to better understand the nonlinear evolution of the pump wave inside the plasma medium. Such studies of nonlinear wave-based models could be crucial in imitating the astrophysical phenomena by laboratory simulations and understanding the inherent essential physics of magnetic turbulence.

Numerical study of the energy loss in the bulb tubular pump system focusing on the off-design conditions based on combined energy analysis methods

The unsteady flow characteristics of the low-head bulb tubular pump highly affects the operation efficiency and stability of the whole system. The purpose of this paper is to investigate the dominating loss area in a typical tubular pump using the combined energy analysis methods. The transient multi-condition flow through the pump system is simulated based on N–S equation integrating SST k-ω model. The power loss characteristics of each flow passage component are analyzed in terms of total pressure variation, entropy production and energy balance equation. The turbulent entropy generation power (PSD') in the entropy production and the turbulent kinetic energy production (PL3) of the energy balance equation are the primary source of power loss, indicating that the fully developed turbulent flow tends to generate considerable loss in the pump system, followed by the power loss of solid wall (PSW and PLW). The distribution of power loss in the impeller and diffuser was comprehensively exhibited and it was found that the undesirable flow patterns are mainly caused by blades and walls. The rim region in impeller domain with volume fraction of 15% induces the energy loss of approximately 45% due to the presence of solid wall and tip leakage vortex (TLV). Furthermore, the individual grid volume is considered to better locate and visualize regions with our great interest, and a number of typical vortex structures are identified under several flow rates showing that the positive attack angle is more likely to caused flow instability and energy loss at low flow rate condition.

Experimental measurements of fluid flow in an 84-pin hexagonal rod bundle with spacer grid for a gas-cooled fast modular reactor

A 50 MWe helium-cooled fast modular reactor (FMR) is under development, and as part of the Department of Energy Integrated Research Project (IRP), Texas A&M University is conducting the thermal-hydraulic characterization of its baseline core configuration. We experimentally investigated the axial and cross flow fields characteristics in the hexagonal fuel rod bundle composed of 84 rods, a central rod, and spacer grids at a Reynolds number of 12,000. A fully transparent experimental facility resembling of one unit of the fuel assembly was constructed. Time-resolved particle image velocimetry (TR-PIV) measurements were performed to characterize hydraulic behavior downstream the spacer grid. Velocity measurements were conducted in the axial and radial direction of the rod bundle. From the PIV velocity vector fields, the full-field flow statistics were computed for the mean velocity, vorticity, and Reynolds stresses. An analysis of the energy decay downstream of the spacer grid was conducted with calculations of secondary-flow intensities, turbulent kinetic energy, power spectrum, and spatial-temporal velocity cross correlations. The vorticity field was obtained and pairs of counter-rotating vortexes were identified using a 3D reconstruction of several measurement planes. The data from this experimental campaign will be used to validate numerical models based on Computational Fluid Dynamics and other codes.

Differential Equation for Turbulence Power Losses and Energy Spectra Based on Consolidated Empirical Results

A second order differential equation for the energy dissipation rate of turbulence is presented. The derivation procedure is explained. The obtained governing equation is a Euler equation, which integration naturally conduces to power laws for the energy dissipation rate as a function of the wavenumber, a result that is extended to the energy spectrum of turbulence. Power laws are obtained for the cases of two equal and two different real roots. For the case of two conjugate complex roots, the solution is a sum of sine and cosine functions of the normal logarithm of the wavenumber. The differential equation accrues from a more basic equation obtained through thermodynamic-type steps that joint part of already consolidated empirical and semi-empirical information on turbulence existing in the literature, and is formally analogue to the Thermodynamics equation of thermal radiation. It is also shown that parameters of turbulence like length and velocity scales may be related to this formulation.

Analysis of Gaussian beam broadening and scintillation index in anisotropic plasma turbulence

In this paper, new expressions for the long-term beam spreading and scintillation index of Gaussian beams in anisotropic plasma turbulent media are derived on the basis of the anisotropic hypersonic plasma turbulent refractive index undulation power spectrum combined with the Rytov approximation theory. Considering the asymmetry of turbulent eddies in the orthogonal xy-plane throughout the path, two anisotropy factors are introduced to parameterize the anisotropy properties of turbulent cells in the horizontal and vertical directions. The spreading and scintillation index of Gaussian beams in plasma turbulence are calculated, and the propagation characteristics of Gaussian beams in anisotropic plasma turbulence are analyzed. Results show that enhancing the anisotropic properties of hypersonic plasma turbulence can significantly improve the propagation performance of Gaussian beams in hypersonic plasma turbulence. The effect of hypersonic plasma turbulence on Gaussian beam increases with the increase of the refractive index undulation variance and the decrease of the turbulent outer scale and anisotropy parameters. The results provide a theoretical basis for the further study of the propagation properties of electromagnetic waves in hypersonic plasma turbulence.

To dee or not to dee: costs and benefits of altering the triangularity of a steady-state DEMO-like reactor

Shaping a tokamak plasma to have a negative triangularity may allow operation in an edge-localized mode-free L-mode regime and with a larger strike-point radius, ameliorating divertor power-handling requirements. However, the shaping has a potential drawback in the form of a lower no-wall ideal beta limit, found using the MHD codes chease and dcon. Using the new fusion systems code faroes, we construct a steady-state DEMO2 reactor model. This model is essentially zero-dimensional and neglects variations in physical mechanisms like turbulence, confinement, and radiative power limits, which could have a substantial impact on the conclusions deduced herein. Keeping its shape otherwise constant, we alter the triangularity and compute the effects on the levelized cost of energy (LCOE). If the tokamak is limited to a fixed B field, then unless other means to increase performance (such as reduced turbulence, improved current drive efficiency or higher density operation) can be leveraged, a negative-triangularity reactor is strongly disfavored in the model due to lower β N limits at negative triangularity, which leads to tripling of the LCOE. However, if the reactor is constrained by divertor heat fluxes and not by magnet engineering, then a negative-triangularity reactor with higher B 0 could be favorable: we find a class of solutions at negative triangularity with lower peak heat flux and lower LCOE than those of the equivalent positive triangularity reactors.

Nature of Supersonic Turbulence and Density Distribution Function in the Multiphase Interstellar Medium

Supersonic flows in the interstellar medium (ISM) are believed to be a key driver of the molecular cloud formation and evolution. Among molecular clouds’ properties, the ratio between the solenoidal and compressive modes of turbulence plays important roles in determining the star formation efficiency. We use numerical simulations of supersonic converging flows of the warm neutral medium (WNM) resolving the thermal instability to calculate the early phase of molecular cloud formation, and we investigate the turbulence structure and the density probability distribution function (density PDF) of the multiphase ISM. We find that both the solenoidal and compressive modes have their power spectrum similar to the Kolmogorov spectrum. The solenoidal (compressive) modes account for ≳80% (≲20%) of the total turbulence power. When we consider both the cold neutral medium (CNM) and the thermally unstable neutral medium (UNM) up to T ≲ 400 K, the density PDF follows the lognormal distribution, whose width is well explained by the known relation from the isothermal turbulence as (where b is the parameter representing the turbulence mode ratio and is the turbulent Mach number). The density PDF of the CNM component alone (T ≤ 50 K), however, exhibits a narrower by a factor of ∼2. These results suggest that observational estimations of b based on the CNM density PDF requires the internal turbulence within each CNM clump but not the interclump relative velocity, the latter of which is instead powered by the WNM/UNM turbulence.

Spatiotemporal nonlinear evolution of the laser pulse and turbulence generation in laser produced plasmas

This study presents a model to understand the behavior of the turbulence generated in the magnetic field of mega gauss order during high-intensity laser interaction with magnetized plasma. The modified nonlinear Schrödinger (MNLS) equation is developed by contemplating the effect of the group velocity dispersion, diffraction, and nonlinearity induced by the relativistic variation of electron mass and the nonlinear ponderomotive force. Numerical simulation is carried out to solve the dimensionless MNLS equation. The simulation results show the generation of the solitary wave type coherent structures in the nonlinear spatiotemporal evolution of the laser pulse at the early stage, but subsequent turbulence generation has also been observed. The ensemble-averaged turbulent power spectrum has been studied and the power-law scaling is approximately ∼ k−1.85(a solid red line of scaling k−1.85 is given for reference). To get insight into the spatiotemporal nonlinear development of the laser pulse, while propagating in the plasma medium, a semi-analytical model has also been presented. The present study could be substantial in replicating astrophysical scenarios by laboratory simulations along with understanding the underlying quintessential physics of magnetic turbulence.