scholarly journals Influence of Wind Buffers on the Aero-Thermal Performance of Skygardens

Fluids ◽  
2020 ◽  
Vol 5 (3) ◽  
pp. 160
Author(s):  
Murtaza Mohammadi ◽  
Paige Wenbin Tien ◽  
John Kaiser Calautit
Keyword(s):  
Computational Modelling ◽  
Cooling Capacity ◽  
Strong Wind ◽  
Design Elements ◽  
Wind Speeds ◽  
High Rise ◽  
Epsilon Method ◽  
Porous Zone ◽  
Wind Comfort ◽  
The Right

Many high-rise buildings have semi-enclosed landscaped spaces, which act as design elements to improve the social and environmental aspects of the building. Designs such as skygardens are open to outdoor airflow and allow occupants to observe the city skyline from a height. Due to their often high location, they are subjected to strong wind speeds and extreme environmental conditions. The current study investigates the effects of three common wind buffers (railing, hedges, and trees) located at a height of 92 m on the performance of a skygarden, in terms of occupants’ wind comfort. Computational fluid dynamics (CFD) simulations were carried out using the realisable k-epsilon method, where the vegetation was modelled as a porous zone with cooling capacity. The computational modelling of the high-rise building and vegetation were validated using previous works. The quality class (QC) of the Lawson comfort criteria was used for the evaluation of the wind comfort across the skygarden. The results indicate that, although the three wind buffers offer varying levels of wind reduction in the skygarden, the overall wind conditions generated are suitable for occupancy. Furthermore, vegetation is also able to offer slight temperature reductions in its wake. The right combination and dimension of these elements can greatly assist in generating aero-thermal comfort across skygardens.

scholarly journals Computational fluid dynamics as a method for studying wind comfort

2021 ◽  
Vol 2119 (1) ◽  
pp. 012155
Author(s):  
V D Meshkova ◽  
A A Dekterev
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Comprehensive Analysis ◽  
Wind Flow ◽  
Flow Acceleration ◽  
Wind Speeds ◽  
High Rise ◽  
High Rise Building ◽  
Streamlined Flow ◽  
Wind Comfort

Abstract The paper presents a comprehensive analysis of the wind flow interaction with a high-rise building, considering various types of streamlined flow acceleration, as well as an assessment of the aerodynamic shadow behind the building, and areas with increased wind speeds. The authors analyze risks caused by these zones, as well as suggest measures to minimize them.

scholarly journals Numerical Investigation of the Wind and Thermal Conditions in Sky Gardens in High-Rise Buildings

Energies ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1380 ◽  
Author(s):  
Murtaza Mohammadi ◽  
John Kaiser Calautit
Keyword(s):  
Thermal Conditions ◽  
Environmental Benefits ◽  
High Wind ◽  
Wind Speeds ◽  
High Rise ◽  
Architectural Elements ◽  
Passive Strategies ◽  
Wind Velocities ◽  
Hot Weather ◽  
Wind Comfort

High-rise buildings are known to be highly energy intensive, adding stress on already stressed resources. Alternatively, designers are looking at passive strategies and investing in architectural elements, such as sky gardens, which could improve the performance of buildings. Sky gardens are green areas located in a building which are exposed to the outdoors. They could provide multifaceted improvements in buildings by introducing environmental benefits to occupants and altering microclimate. This study aims to determine the wind comfort and thermal condition in sky gardens in high-rise buildings using numerical modelling. Different geometrical configurations of sky gardens were simulated and analysed. Based on the initial results, the study reveals that sky gardens can generate high wind velocities of the order ~10 m/s when located on a high-rise building. The addition of features such as trees and other architectural elements, which can act as a buffer, can help attenuate the high wind speeds and creating habitable spaces. The reduction varies 50%–80%, depending on the location and spatial domain of the sky garden. Furthermore, the study also investigated the reduction in air temperature due to the addition of trees, which can further reduce temperature in hot weather.

scholarly journals On certain development aspects of an ipsas-based system-target approach to evaluation of net asset sustainability level projects in high-rise construction

2018 ◽  
Vol 33 ◽  
pp. 02071 ◽  
Author(s):  
Ruben Kazaryan
Keyword(s):  
Public Sector ◽  
Financial Reporting ◽  
Legal Status ◽  
Accounting Standards ◽  
Legal Aspects ◽  
Financial Reporting Standards ◽  
High Rise ◽  
Net Assets ◽  
Autonomous Institution ◽  
The Right

Problems of accounting and reporting of net assets and the procedure of their formation taking into account the specifics of the economic and legal status of property of a non-commercial autonomous institution are some of the most controversial in the accounting for entities of the public sector. The study focuses on justification of accounting rules for net assets of public sector entities. The methods used in the study are as follows: comparison, synthesis, analysis, logical approach, and system approach. The article examines legal aspects and specifics of recognition of assets of public sector entities in accordance with IPSAS standards (International Public Sector Accounting Standards are a set of accounting standards issued by IPSASB (Council for International Financial Reporting Standards for Public Sector Organizations) used by state-owned enterprises worldwide in preparation of financial statements as of the 31st of August, 2015. The most crucial factor in the modeling of key performance indicators of the system-target approach to estimation of the sustainability level of net assets on the basis of IPSAS is a multicriterial evaluation of the basic management strategy for quality system elements used in operational and strategic planning projects operations in high-rise construction. We offer an alternative evaluation of assets due to be returned to the right holder (the state controller) in the event of liquidation of a public sector entity.

scholarly journals Wind Speed Retrieval from Simulated RADARSAT Constellation Mission Compact Polarimetry SAR Data for Marine Application

2019 ◽  
Vol 11 (14) ◽  
pp. 1682 ◽  
Author(s):  
Torsten Geldsetzer ◽  
Shahid K. Khurshid ◽  
Kerri Warner ◽  
Filipe Botelho ◽  
Dean Flett
Keyword(s):  
Wind Speed ◽  
Low Noise ◽  
Quality Data ◽  
Band Model ◽  
Data Set ◽  
Wind Retrieval ◽  
Wind Speeds ◽  
Geophysical Model ◽  
The Right ◽  
Quality Threshold

RADARSAT Constellation Mission (RCM) compact polarimetry (CP) data were simulated using 504 RADARSAT-2 quad-pol SAR images. These images were used to samples CP data in three RCM modes to build a data set with co-located ocean wind vector observations from in situ buoys on the West and East coasts of Canada. Wind speeds up to 18 m/s were included. CP and linear polarization parameters were related to the C-band model (CMOD) geophysical model functions CMOD-IFR2 and CMOD5n. These were evaluated for their wind retrieval potential in each RCM mode. The CP parameter Conformity was investigated to establish a data-quality threshold (>0.2), to ensure high-quality data for model validation. An accuracy analysis shows that the first Stokes vector (SV0) and the right-transmit vertical-receive backscatter (RV) parameters were as good as the VV backscatter with CMOD inversion. SV0 produced wind speed retrieval accuracies between 2.13 m/s and 2.22 m/s, depending on the RCM mode. The RCM Medium Resolution 50 m mode produced the best results. The Low Resolution 100 m and Low Noise modes provided similar results. The efficacy of SV0 and RV imparts confidence in the continuity of robust wind speed retrieval with RCM CP data. Three image-based case studies illustrate the potential for the application of CP parameters and RCM modes in operational wind retrieval systems. The results of this study provide guidance to direct research objectives once RCM is launched. The results also provide guidance for operational RCM data implementation in Canada’s National SAR winds system, which provides near-real-time wind speed estimates to operational marine forecasters and meteorologists within Environment and Climate Change Canada.

scholarly journals Bayesian Model Averaging for Wind Speed Ensemble Forecasts Using Wind Speed and Direction

2017 ◽  
Vol 32 (6) ◽  
pp. 2217-2227 ◽  
Author(s):  
Siri Sofie Eide ◽  
John Bjørnar Bremnes ◽  
Ingelin Steinsland
Keyword(s):  
Wind Speed ◽  
Wind Direction ◽  
Bayesian Model Averaging ◽  
Weather Prediction ◽  
Model Averaging ◽  
Strong Wind ◽  
Ensemble Forecasts ◽  
Wind Speeds ◽  
Low Wind Speeds ◽  
The One

Abstract In this paper, probabilistic wind speed forecasts are constructed based on ensemble numerical weather prediction (NWP) forecasts for both wind speed and wind direction. Including other NWP variables in addition to the one subject to forecasting is common for statistical calibration of deterministic forecasts. However, this practice is rarely seen for ensemble forecasts, probably because of a lack of methods. A Bayesian modeling approach (BMA) is adopted, and a flexible model class based on splines is introduced for the mean model. The spline model allows both wind speed and wind direction to be included nonlinearly. The proposed methodology is tested for forecasting hourly maximum 10-min wind speeds based on ensemble forecasts from the European Centre for Medium-Range Weather Forecasts at 204 locations in Norway for lead times from +12 to +108 h. An improvement in the continuous ranked probability score is seen for approximately 85% of the locations using the proposed method compared to standard BMA based on only wind speed forecasts. For moderate-to-strong wind the improvement is substantial, while for low wind speeds there is generally less or no improvement. On average, the improvement is 5%. The proposed methodology can be extended to include more NWP variables in the calibration and can also be applied to other variables.

scholarly journals AN INVESTIGATION OF DIFFERENT FORMWORK SYSTEM FOR HIGH RISE BUILDING CONSTRUCTION AND FOR DECISION SUPPORT SYSTEM

2020 ◽  
Author(s):  
SHWETA SAGAR ◽  
◽  
VIRENDRA KUMAR PAUL ◽  
Keyword(s):  
Decision Support ◽  
Decision Support System ◽  
Construction Industry ◽  
Support System ◽  
White Paper ◽  
Building Construction ◽  
High Rise ◽  
High Rise Building ◽  
The Right ◽  
System Selection

The most important aspect of any successful structural construction is the formwork system. Formwork itself defines as the temporary structure into which the concrete placed to obtain its desired shape and gains its weight to withstand against various loading conditions. This paper focuses on the two parts 1. Identified different formwork systems using in Indian construction industry for high-rise building construction and 2. Explanations of the decision support system for formwork system so that a decision-maker decides or makes the right choice for the selection of formwork system. This study employed a literature review approach (journal paper, research paper, technical articles & notes, and white paper). The methodology divided into two parts; firstly, the identification of the formwork systems used in the construction industry and secondly, to study a brief about decision support system and for formwork system by which the ease to make a decision support frame for the formwork system selection. This paper reflects the different formwork system typology used in the construction industry for high-rise buildings. The outcome of this paper helps to establish the baseline to develop decision support for the formwork system selection.

The Probability Distribution of Land Surface Wind Speeds

2011 ◽  
Vol 24 (15) ◽  
pp. 3892-3909 ◽  
Author(s):  
Adam H. Monahan ◽  
Yanping He ◽  
Norman McFarlane ◽  
Aiguo Dai
Keyword(s):  
Boundary Layer ◽  
Weibull Distribution ◽  
Land Surface ◽  
Wind Shear ◽  
Surface Wind ◽  
Nocturnal Boundary Layer ◽  
Global Network ◽  
Strong Wind ◽  
Wind Speeds ◽  
Tropospheric Wind

Abstract The probability density function (pdf) of land surface wind speeds is characterized using a global network of observations. Daytime surface wind speeds are shown to be broadly consistent with the Weibull distribution, while nighttime surface wind speeds are generally more positively skewed than the corresponding Weibull distribution (particularly in summer). In the midlatitudes, these strongly positive skewnesses are shown to be generally associated with conditions of strong surface stability and weak lower-tropospheric wind shear. Long-term tower observations from Cabauw, the Netherlands, and Los Alamos, New Mexico, demonstrate that lower-tropospheric wind speeds become more positively skewed than the corresponding Weibull distribution only in the shallow (~50 m) nocturnal boundary layer. This skewness is associated with two populations of nighttime winds: (i) strongly stably stratified with strong wind shear and (ii) weakly stably or unstably stratified with weak wind shear. Using an idealized two-layer model of the boundary layer momentum budget, it is shown that the observed variability of the daytime and nighttime surface wind speeds can be accounted for through a stochastic representation of intermittent turbulent mixing at the nocturnal boundary layer inversion.

Realisation and testing of novel fully articulated bird-inspired flapping wings for efficient and agile UAVs

2021 ◽  
pp. 1-35
Author(s):  
D. Kumar ◽  
T. Goyal ◽  
S. Kamle ◽  
P.M. Mohite ◽  
E.M. Lau
Keyword(s):  
Aerodynamic Performance ◽  
Image Correlation ◽  
Right Wing ◽  
Left Wing ◽  
Bank Angle ◽  
Rolling Moment ◽  
Wind Speeds ◽  
Optimal Values ◽  
The Right ◽  
Dic Technique

Abstract Large birds have evolved an effective wing anatomy and mechanics, enabling airborne mastery of manoeuvres and endurance. For these very reasons, they are difficult to replicate and study. The aim of the present work is to achieve active wing articulations to mimic natural bird flapping towards efficient and agile Unmanned Aerial Vehicles (UAVs). The proposed design, bio-mimicking the black-headed gull, Larus ridibundus, has three active and independent servo-controlled wing joints at the shoulder, elbow and wrist to achieve complex controls. The construction of the wing is realised through a polymeric skin and carbon fibre–epoxy composite spars and ribs. The wing movements (flapping, span reduction and twisting) envelopes of the full-scale robotic gull (Robogull) are examined using the Digital Image Correlation (DIC) technique and laser displacement sensing. Its aerodynamic performance was evaluated in a wind tunnel at various flapping parameters, wind speeds and angles of attack. It is observed that a flapping amplitude of 45 $^\circ$ is more favourable than 90 $^\circ$ for generating higher lift and thrust, while also depending on the presence of span reduction, twist and wind speed. The model performs better at a flying velocity of 4m/s as compared with 8m/s. Both lift and thrust are high at a higher flapping frequency of 2.5Hz. Combined variation of the flapping frequency and stroke ratio should be considered for better aerodynamic performance. The combination of a lower stroke ratio of 0.5 with a flapping frequency of 2.5Hz generates higher lift and thrust than other combinations. Span reduction and wing twist notably and independently enhance lift and thrust, respectively. An increase in the angle-of-attack increases lift but decreases thrust. The model can also generate a significant rolling moment when set at a bank angle of 20 $^\circ$ and operated with independently controlled flapping amplitudes for the wings (45 $^\circ$ for the left wing and 90 $^\circ$ for the right wing). Based on the optimal values for the flapping amplitude (45 $^\circ$ ), flapping frequency (2.5Hz) and flying velocity (4m/s), the Strouhal number (St) of the Robogull model is 0.24, lying in the optimal range ( $0.2 < \mathrm{St} < 0.4$ ) for natural flyers and swimmers.

scholarly journals Catch Characteristics of Precipitation Gauges in High-Latitude Regions with High Winds

2006 ◽  
Vol 7 (5) ◽  
pp. 984-994 ◽  
Author(s):  
Konosuke Sugiura ◽  
Tetsuo Ohata ◽  
Daqing Yang
Keyword(s):  
Wind Speed ◽  
High Latitude ◽  
Cold Climate ◽  
Strong Wind ◽  
Blowing Snow ◽  
High Wind ◽  
Wind Speeds ◽  
Solid Precipitation ◽  
High Winds ◽  
Correction Equations

Abstract Intercomparison of solid precipitation measurement at Barrow, Alaska, has been carried out to examine the catch characteristics of various precipitation gauges in high-latitude regions with high winds and to evaluate the applicability of the WMO precipitation correction procedures. Five manual precipitation gauges (Canadian Nipher, Hellmann, Russian Tretyakov, U.S. 8-in., and Wyoming gauges) and a double fence intercomparison reference (DFIR) as an international reference standard have been installed. The data collected in the last three winters indicates that the amount of solid precipitation is characteristically low, and the zero-catch frequency of the nonshielded gauges is considerably high, 60%–80% of precipitation occurrences. The zero catch in high-latitude high-wind regions becomes a significant fraction of the total precipitation. At low wind speeds, the catch characteristics of the gauges are roughly similar to the DFIR, although it is noteworthy that the daily catch ratios decreased more rapidly with increasing wind speed compared to the WMO correction equations. The dependency of the daily catch ratios on air temperature was confirmed, and the rapid decrease in the daily catch ratios is due to small snow particles caused by the cold climate. The daily catch ratio of the Wyoming gauge clearly shows wind-induced losses. In addition, the daily catch ratios are considerably scattered under strong wind conditions due to the influence of blowing snow. This result suggests that it is not appropriate to extrapolate the WMO correction equations for the shielded gauges in high-latitude regions for high wind speed of over 6 m s−1.

scholarly journals Graz Lagrangian Model (GRAL) for Pollutants Tracking and Estimating Sources Partial Contributions to Atmospheric Pollution in Highly Urbanized Areas

Atmosphere ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1375
Author(s):  
Aleksey A. Romanov ◽  
Boris A. Gusev ◽  
Egor V. Leonenko ◽  
Anastasia N. Tamarovskaya ◽  
Alexander S. Vasiliev ◽  
...  
Keyword(s):  
Air Quality ◽  
Urban Landscape ◽  
Weather Conditions ◽  
Lagrangian Model ◽  
Emission Sources ◽  
Computational Domain ◽  
Surface Atmospheric Layer ◽  
Wind Speeds ◽  
High Rise ◽  
Heterogeneous Landscape

Computational modeling allows studying the air quality problems in depth and provides the best solution reducing the population risks. This research demonstrates the Graz Lagrangian model effectiveness for assessing emission sources contributions to the air pollution: particles tracking and accumulation estimate. The article describes model setting up parameters and datasets preparation for the analysis. The experiment simulated the dispersion from the main groups of emission sources for real weather conditions during 96 h of December 2018, when significant excess of NO2, CO, SO2, PM10, and benzo(a)pyrene concentrations were observed in the Krasnoyarsk surface atmospheric layer. The computational domain was a parallelepiped of 40 × 30 × 2.5 km, which was located deep inside the Eurasian continent on a heterogeneous landscape exaggerated by high-rise buildings, with various pollutions sources and the ice-free Yenisei River. The results demonstrated an excellent applicability of the Lagrange model for hourly tracking of particle trajectories, taking into account the urban landscape. For values <1 MPC (maximum permissible concentration) of peak pollutants concentrations, the coincidences were 93 cases, and for values < 0.1 shares of MPC, there were 36 cases out of the total number of 97. The same was found for the average daily concentration for values <1 MPC—31, and for values <0.1 MPC—5 matches out of 44. Wind speeds COR—65.3%, wind directions COR—68.6%. The Graz Lagrangian model showed the ability to simulate air quality problems in the Krasnoyarsk greater area conditions.

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