scholarly journals Аtmospheric wind flow around the mountain landscape in the vicinity of Danang airport and flight safety issues

2021 ◽  
Vol 24 (6) ◽  
pp. 27-41
Author(s):  
V. V. Vyshinsky ◽  
K. T. Zoan
Keyword(s):  
Vortex Structure ◽  
Stokes Equations ◽  
Vortex Structures ◽  
Computational Grids ◽  
Maximum Pressure ◽  
Mountainous Area ◽  
Wind Flow ◽  
Large Space ◽  
Mountain Landscape ◽  
The Impact

Wind boundary layer flow over the mountain landscape and large structures located around runways (RWs) creates coherent vortex structures (CVSs) that can cross a glideslope and airspace in the vicinity of an airport. The aircraft, encountering a vortex structure, experiences significant changes of the aerodynamic forces and moments, what is especially hazardous due to proximity to terrain. From a mathematical point of view, the solution of this problem presents a challenge due to extremely large space – time scale of the phenomenon, the lack of relevant atmospheric models, as well as comprehensive initial – boundary conditions in numerical modeling. In this paper, a composite solution is constructed: the CVSs area generation is computed in sufficient details within the framework of the grid method. Based on the data obtained in the approximation of analytical functions, an initial vortex structure is formed, the evolution and stochastics of which are modeled within the potential approximation by means of Rankine vortices. The evaluation of the forces and moments increment from the impact of vortex structures on the aircraft was carried out by the panel method using the engineering approach. As an example, the CVSs, resulting from wind flow around the mountainous area of the Son Tra Peninsula, that is located short of RWs 35R-17L and 35L-17R of Da Nang airport, are investigated. To improve the computational grids quality and verify the method of solving the boundary value problem for the Reynolds-averaged Navier-Stokes equations, we used the criteria based on the principle of maximum pressure, requiring Q-parameter positivity property in the vortices cores and flow separation regions. A CVS related aviation event, involving a passenger aircraft MC-21, is studied. The aircraft, after takeoff from RW 35R-17L setting the course close to the direction of the vortex wind structure axis from the Son Tra Peninsula, encountered the mountainous area CVS.

scholarly journals Flow Pressure Behavior Downstream of Ski Jumps

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 168 ◽  
Author(s):  
Agostino Lauria ◽  
Giancarlo Alfonsi ◽  
Ali Tafarojnoruz
Keyword(s):  
High Speed ◽  
Stokes Equations ◽  
Dynamic Pressure ◽  
Pressure Head ◽  
Navier Stokes ◽  
Maximum Pressure ◽  
Navier Stokes Equations ◽  
Free Jet ◽  
Jet Characteristics ◽  
The Impact

Ski jump spillways are frequently implemented to dissipate energy from high-speed flows. The general feature of this structure is to transform the spillway flow into a free jet up to a location where the impact of the jet creates a plunge pool, representing an area for potential erosion phenomena. In the present investigation, several tests with different ski jump bucket angles are executed numerically by means of the OpenFOAM® digital library, taking advantage of the Reynolds-averaged Navier–Stokes equations (RANS) approach. The results are compared to those obtained experimentally by other authors as related to the jet length and shape, obtaining physical insights into the jet characteristics. Particular attention is given to the maximum pressure head at the tailwater. Simple equations are proposed to predict the maximum dynamic pressure head acting on the tailwater, as dependent upon the Froude number, and the maximum pressure head on the bucket. Results of this study provide useful suggestions for the design of ski jump spillways in dam construction.

scholarly journals INVESTIGATION HYPERBOLIC PARABOLOID SHELL IN THE WIND TUNNEL AND COMPARISON WITH NUMERICAL SIMULATIONS

2018 ◽  
Vol 64 ◽  
Author(s):  
V.V. Stojanov ◽  
S. Jgalli
Keyword(s):  
Numerical Simulation ◽  
Wind Tunnel ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Wind Flow ◽  
Hyperbolic Paraboloid ◽  
Ansys Fluent ◽  
Navier Stokes Equations ◽  
Basic Model ◽  
The Impact

There are different ways to determine aerodynamic parameters, using analytical and experimental data for analyzing the behavior of structures when exposed to wind load. To date, the most developed is considered a numerical method for determining the characteristics of the above methods, based on the numerical solution of the Navier-Stokes equations. The accuracy of the results obtained using such a calculation method and obtaining the values of aerodynamic forces has increased due to the revision of mathematical models and the development of software complexes for the discretization of object bodies. This article gives an analytical overview of the results of research in the field of study the impact of wind loads on hypar (shell square in plan with the form of a hyperbolic paraboloid). The features of the investigated forms a discretization surface depending on pressure coefficients obtained in foreign literatures. Particular attention is paid to the numerical determination of aerodynamic coefficients on the surfaces of a hyperbolic paraboloid. The results were discussed and the nature of the distribution of coefficients depending on the angle of attack of the wind. Achieved analytical comparison computer modeling turbulent wind flows, based on solving the Reynolds equations arising from the use of averaging the Navier-Stokes equations. The basic model of turbulence such as: k-ε Standard Model; MMK; DBN; Shear-Stress Transport k-ω model; Transition k-kl-ω model. The possibility of choosing one or another model depending on the properties and characteristics of the wind flow is analyzed, for application in numerical simulation of wind flow around hyperbolic shells. The same was done, a comparative analysis of the results of physical testing in a wind tunnel with a numerical simulation in Ansys Fluent.

scholarly journals Influence of air shock wave on shelter

2020 ◽  
pp. 133-144
Author(s):  
Volodymyr Kotsiuruba ◽  
Ivan Datsenko ◽  
Volodymyr Dachkovsky ◽  
Ruslan Cherevko ◽  
Vasyl Polyulyak ◽  
...  
Keyword(s):  
Shock Wave ◽  
Stokes Equations ◽  
Experimental Studies ◽  
Navier Stokes ◽  
Maximum Pressure ◽  
Navier Stokes Equations ◽  
Pressure Time ◽  
Protective Structures ◽  
Short Time ◽  
The Impact

In modern conditions, sheltering people in protective structures, as a way of protection from dangers, in combination with evacuation from the affected areas (pollution) and the use of personal protective equipment, increases the reliability of public protection. In conditions when evacuation measures from cities can be complicated in a short time, protection of the population in shelters becomes the only possible and effective. Therefore, an important task is to study the impact of loads caused by the explosion of various munitions, substantiate recommendations for improving the protective properties of the shelter and the choice of their location. The most common issues are considered in the article that arise during the arrangement of shelter in buildings and outside them. Based on experimental studies, Taylor's formula and the system of non-stationary Navier-Stokes equations for gas, it’s conducted an analysis of the influence of external and internal factors on the possible nature of the dynamic load from the shock wave on buildings, structures and structural elements in which shelters are located. The results of studies of the parameters of dynamic loads showed that if the storage facilities are located in the basements of buildings, their stability is characterized by three parameters: maximum pressure, time to increase the load to maximum and effective time. The parameters of the loads and the law of their change over the time depend on the location of the structure relative to the surface of the earth and the building, the force of the explosion and the distance to the center of the explosion.

Effect of the Separating Distance of Twin Buildings on the Generated Flow Structure

2010 ◽  
Vol 297-301 ◽  
pp. 924-929
Author(s):  
Inès Bhouri Baouab ◽  
Nejla Mahjoub Said ◽  
Hatem Mhiri ◽  
Georges Le Palec ◽  
Philippe Bournot
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Reynolds Stress Model ◽  
Navier Stokes ◽  
Wind Flow ◽  
Turbulent Model ◽  
Navier Stokes Equations ◽  
Twin Buildings ◽  
Volume Method ◽  
Numerical Examination

The present work consists in a numerical examination of the dispersion of pollutants discharged from a bent chimney and crossing twin similar cubic obstacles placed in the lee side of the source. The resulting flow is assumed to be steady, three-dimensional and turbulent. Its modelling is based upon the resolution of the Navier Stokes equations by means of the finite volume method together with the RSM (Reynolds Stress Model) turbulent model. This examination aims essentially at detailing the wind flow perturbations, the recirculation and turbulence generated by the presence of the twin cubic obstacles placed tandem at different spacing distances (gaps): W = 4 h, W = 2 h and W = 1 h where W is the distance separating both buildings.

Numerical Investigation of Focused Waves and Their Interaction With a Vertical Cylinder Using REEF3D

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Hans Bihs ◽  
Mayilvahanan Alagan Chella ◽  
Arun Kamath ◽  
Øivind Asgeir Arntsen
Keyword(s):  
Free Surface ◽  
Stokes Equations ◽  
Free Surface Flows ◽  
Surface Elevation ◽  
Numerical Wave Tank ◽  
Free Surface Elevation ◽  
Wave Tank ◽  
Numerical Wave ◽  
Focused Wave ◽  
The Impact

For the stability of offshore structures, such as offshore wind foundations, extreme wave conditions need to be taken into account. Waves from extreme events are critical from the design perspective. In a numerical wave tank, extreme waves can be modeled using focused waves. Here, linear waves are generated from a wave spectrum. The wave crests of the generated waves coincide at a preselected location and time. Focused wave generation is implemented in the numerical wave tank module of REEF3D, which has been extensively and successfully tested for various wave hydrodynamics and wave–structure interaction problems in particular and for free surface flows in general. The open-source computational fluid dynamics (CFD) code REEF3D solves the three-dimensional Navier–Stokes equations on a staggered Cartesian grid. Higher order numerical schemes are used for time and spatial discretization. For the interface capturing, the level set method is selected. In order to test the generated waves, the time series of the free surface elevation are compared with experimental benchmark cases. The numerically simulated free surface elevation shows good agreement with experimental data. In further computations, the impact of the focused waves on a vertical circular cylinder is investigated. A breaking focused wave is simulated and the associated kinematics is investigated. Free surface flow features during the interaction of nonbreaking focused waves with a cylinder and during the breaking process of a focused wave are also investigated along with the numerically captured free surface.

Modeling of the Vortex-Structure in a Particle-Laden Mixing-Layer

2005 ◽  
Author(s):  
Jens A. Melheim ◽  
Stefan Horender ◽  
Martin Sommerfeld
Keyword(s):  
Vortex Structure ◽  
Stokes Equations ◽  
Fluid Velocity ◽  
Mixing Layer ◽  
Equation Model ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Calculated Concentration ◽  
Langevin Model ◽  
Particle Velocities

Numerical calculations of a particle-laden turbulent horizontal mixing-layer based on the Eulerian-Lagrangian approach are presented. Emphasis is given to the determination of the stochastic fluctuating fluid velocity seen by the particles in anisotropic turbulence. The stochastic process for the fluctuating velocity is a “Particle Langevin equation Model”, based on the Simplified Langevin Model. The Reynolds averaged Navier-Stokes equations are closed by the standard k-epsilon turbulence model. The calculated concentration profile and the mean, the root-mean-square (rms) and the cross-correlation terms of the particle velocities are compared with particle image velocimetry (PIV) measurements. The numerical results agree reasonably well with the PIV data for all of the mentioned quantities. The importance of the modeled vortex structure “seen” by the particles is discussed.

scholarly journals Wind Data Analysis and Wind Flow Simulation Over Large Areas

2014 ◽  
Vol 10 (1) ◽  
pp. 38-45
Author(s):  
Angel Terziev ◽  
Ivan Antonov ◽  
Rositsa Velichkova
Keyword(s):  
Renewable Energy ◽  
Wind Energy ◽  
Renewable Energy Sources ◽  
Energy Sources ◽  
Wind Flow ◽  
Energy Potential ◽  
Wind Potential ◽  
Wind Energy Potential ◽  
The Impact

Abstract Increasing the share of renewable energy sources is one of the core policies of the European Union. This is because of the fact that this energy is essential in reducing the greenhouse gas emissions and securing energy supplies. Currently, the share of wind energy from all renewable energy sources is relatively low. The choice of location for a certain wind farm installation strongly depends on the wind potential. Therefore the accurate assessment of wind potential is extremely important. In the present paper an analysis is made on the impact of significant possible parameters on the determination of wind energy potential for relatively large areas. In the analysis the type of measurements (short- and long-term on-site measurements), the type of instrumentation and the terrain roughness factor are considered. The study on the impact of turbulence on the wind flow distribution over complex terrain is presented, and it is based on the real on-site data collected by the meteorological tall towers installed in the northern part of Bulgaria. By means of CFD based software a wind map is developed for relatively large areas. Different turbulent models in numerical calculations were tested and recommendations for the usage of the specific models in flows modeling over complex terrains are presented. The role of each parameter in wind map development is made. Different approaches for determination of wind energy potential based on the preliminary developed wind map are presented.

scholarly journals The impact of solar and galactic cosmic rays on atmospheric vortex structures

2017 ◽  
Vol 14 (2) ◽  
pp. 209-220
Author(s):  
N.I. Izhovkina ◽  
◽  
S.N. Artekha ◽  
N.S. Erokhin ◽  
L.A. Mikhailovskaya ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Galactic Cosmic Rays ◽  
Vortex Structures ◽  
The Impact

ANALISIS SROI (SOCIAL RETURN ON INVESTMENT) DALAM MENGUKUR KEBERHASILAN PROGRAM CSR MIKROHYDRO OLEH PT. PJB UP PAITON DI DESA ANDUNGBIRU, KABUPATEN PROBOLINGGO

2020 ◽  
Vol 2 (2) ◽  
pp. 15-22
Author(s):  
Veronica Sri Astuti
Keyword(s):  
Environmental Sustainability ◽  
Return On Investment ◽  
Mountainous Area ◽  
Hydro Power ◽  
Colonial Era ◽  
Social Return On Investment ◽  
The People ◽  
The Social ◽  
The Impact ◽  
Electricity Infrastructure

This study aims to determine the impact / benefits of the CSR Mikrohydro program by PT. PJB UP Paiton in Andungbiru Village, Probolinggo Regency. This can be seen by using the Social Return On Investment (SROI) analysis. Andungbiru Village is a village that is located very remote and is a mountainous area, where the electricity infrastructure is from very minimal even almost unusable. CSR Mikrohydro by PT. PJB UP Paiton helps the people of Andungbiru Village by reactivating the PLTMH (Micro Hydro Power Plant) which once existed during the Dutch colonial era. SROI analysis shows that CSR Mikrohydro by PT. PJB UP Paiton in Andungbiru Village has succeeded in providing benefits and empowering the Andungbiru Village community economically and socially, as well as maintaining environmental sustainability. Keywords: Social Return On Investment; CSR

Sacred Mountain, Landscape, and Afterlife

2021 ◽  
pp. 151-171
Author(s):  
Gideon Fujiwara
Keyword(s):  
Meaningful Life ◽  
Mountain Landscape ◽  
Sacred Mountain ◽  
Imperial Japan ◽  
The Impact

This chapter examines the imagining of the dual “countries” of Tsugaru and Imperial Japan in Tsuruya Ariyo's poetry and prose about the sacred Mount Iwaki and the gods who preside over the peaks. It presents Ariyo's emphasis on the reality of the spirit realm by citing a case of a local samurai facing divine abduction while on the mountain. The chapter introduces Ariyo's Enjoyment Visible and Invisible in which he validated Hirata Atsutane's view that souls of the deceased were active and served “Imperial deity” Ōkuninushi in the spirit realm. It also emphasizes enjoyment as the key to living a meaningful life extending from this world to the afterlife, while his norito reflects his reverence for gods and ancestors. Ultimately, the chapter investigates the impact of Ariyo and Hirao Rosen's works about spirits and the spirit realm on more politically urgent matters in the late-Tokugawa to Restoration years.

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