scholarly journals Area Assessment of a Pedestrian Wind Environment Using Point Wind Speed Measurements

2021 ◽  
Author(s):  
◽  
Benjamin Jan Kepka
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Measurement Techniques ◽  
Area Measurement ◽  
Wind Environment ◽  
Wind Speeds ◽  
Development Site ◽  
In Series ◽  
Data Points ◽  
The Impact

<p>This research has successfully produced a means of creating a reliable area measurement of a pedestrian level wind environment from a reasonable number of point wind speed measurements. To complete this aim a contouring script was developed through MATLAB. The script has the ability to read in series of point wind speed measurements coupled with cartesian co-ordinates and generate a reliable contour diagram. The foundation for this research is a resource of over 150 wind tunnel tests conducted for code compliance in Wellington City. The District Plan in Wellington requires any building over 18.6m in height to have a wind tunnel analysis conducted to assess the changes in wind speed with respect to pedestrian safety. Wellington compliance criteria require two forms of measurement to be conducted. Point measurements are taken to quantify wind speeds accurately, but are unable to efficiently assess large areas. Area measurement techniques are used to assess the comparative windiness of zones around the development site. Through examination of 3000 measured data points it has been demonstrated that the correlation between these two measurement techniques is relatively low. Until now, neither test alone has been sufficient to accurately quantify the impact of a new development on the pedestrian level wind environment as a whole. Interpolation methods were used to generate pseudo measurements between points at which wind speeds were measured. A series of three building configurations were assessed using the MATLAB script to visualise the effect of increasing building height on pedestrian level winds. The building configurations assessed were: a uniformly distributed grid of 25 half cubes (60m x 60m x 30m), central full cube (60m x 60m x 60m), and, a central tall tower (60m x 60m x 240m). Each building configuration was simulated through the contouring script and the resultant contours were assessed to ensure a realistic depiction of easily predictable wind flow patterns such as downwash and the corner effect. The resolution of the output contours in any case is directly related to the number of point wind speed measurements used. It has been found that measurement points should be more densely located (15m in scale) around the site in question, and more sparsely located (30m in scale) around the outer regions of the desired testing area. This is the most efficient method of generating contours for use in commercial pedestrian level wind laboratories. Mathematically generated contours have the potential to provide a more reliable output than those produced through current methods of area testing.</p>

scholarly journals Area Assessment of a Pedestrian Wind Environment Using Point Wind Speed Measurements

2021 ◽  
Author(s):  
◽  
Benjamin Jan Kepka
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Measurement Techniques ◽  
Area Measurement ◽  
Wind Environment ◽  
Wind Speeds ◽  
Development Site ◽  
In Series ◽  
Data Points ◽  
The Impact

<p>This research has successfully produced a means of creating a reliable area measurement of a pedestrian level wind environment from a reasonable number of point wind speed measurements. To complete this aim a contouring script was developed through MATLAB. The script has the ability to read in series of point wind speed measurements coupled with cartesian co-ordinates and generate a reliable contour diagram. The foundation for this research is a resource of over 150 wind tunnel tests conducted for code compliance in Wellington City. The District Plan in Wellington requires any building over 18.6m in height to have a wind tunnel analysis conducted to assess the changes in wind speed with respect to pedestrian safety. Wellington compliance criteria require two forms of measurement to be conducted. Point measurements are taken to quantify wind speeds accurately, but are unable to efficiently assess large areas. Area measurement techniques are used to assess the comparative windiness of zones around the development site. Through examination of 3000 measured data points it has been demonstrated that the correlation between these two measurement techniques is relatively low. Until now, neither test alone has been sufficient to accurately quantify the impact of a new development on the pedestrian level wind environment as a whole. Interpolation methods were used to generate pseudo measurements between points at which wind speeds were measured. A series of three building configurations were assessed using the MATLAB script to visualise the effect of increasing building height on pedestrian level winds. The building configurations assessed were: a uniformly distributed grid of 25 half cubes (60m x 60m x 30m), central full cube (60m x 60m x 60m), and, a central tall tower (60m x 60m x 240m). Each building configuration was simulated through the contouring script and the resultant contours were assessed to ensure a realistic depiction of easily predictable wind flow patterns such as downwash and the corner effect. The resolution of the output contours in any case is directly related to the number of point wind speed measurements used. It has been found that measurement points should be more densely located (15m in scale) around the site in question, and more sparsely located (30m in scale) around the outer regions of the desired testing area. This is the most efficient method of generating contours for use in commercial pedestrian level wind laboratories. Mathematically generated contours have the potential to provide a more reliable output than those produced through current methods of area testing.</p>

scholarly journals A Novel Sea Surface Roughness Parameterization Based on Wave State and Sea Foam

2021 ◽  
Vol 9 (3) ◽  
pp. 246
Author(s):  
Difu Sun ◽  
Junqiang Song ◽  
Xiaoyong Li ◽  
Kaijun Ren ◽  
Hongze Leng
Keyword(s):  
Surface Roughness ◽  
Wind Speed ◽  
Drag Coefficient ◽  
Sea Surface ◽  
High Wind Speed ◽  
Wave State ◽  
Wind Speeds ◽  
Sea Surface Roughness ◽  
Extreme Wind ◽  
The Impact

A wave state related sea surface roughness parameterization scheme that takes into account the impact of sea foam is proposed in this study. Using eight observational datasets, the performances of two most widely used wave state related parameterizations are examined under various wave conditions. Based on the different performances of two wave state related parameterizations under different wave state, and by introducing the effect of sea foam, a new sea surface roughness parameterization suitable for low to extreme wind conditions is proposed. The behaviors of drag coefficient predicted by the proposed parameterization match the field and laboratory measurements well. It is shown that the drag coefficient increases with the increasing wind speed under low and moderate wind speed conditions, and then decreases with increasing wind speed, due to the effect of sea foam under high wind speed conditions. The maximum values of the drag coefficient are reached when the 10 m wind speeds are in the range of 30–35 m/s.

Study on the Relation Between Side Ratios of Rectangular Cross Sections and Secondary Vortices at Trailing Edge in Motion-Induced Vortex Excitation

2017 ◽  
Author(s):  
Kazutoshi Matsuda ◽  
Kusuo Kato ◽  
Kouki Arise ◽  
Hajime Ishii
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Cross Sections ◽  
Leading Edge ◽  
Trailing Edge ◽  
Wind Speeds ◽  
Smoke Flow ◽  
Flow Visualizations ◽  
Institute Of Technology ◽  
Secondary Vortices

According to the results of conventional wind tunnel tests on rectangular cross sections with side ratios of B/D = 2–8 (B: along-wind length (m), D: cross-wind length (m)), motion-induced vortex excitation was confirmed. The generation of motion-induced vortex excitation is considered to be caused by the unification of separated vortices from the leading edge and secondary vortices at the trailing edge [1]. Spring-supported test for B/D = 1.18 was conducted in a closed circuit wind tunnel (cross section: 1.8 m high×0.9 m wide) at Kyushu Institute of Technology. Vibrations were confirmed in the neighborhoods of reduced wind speeds Vr = V/fD = 2 and Vr = 8 (V: wind speed (m/s), f: natural frequency (Hz)). Because the reduced wind speed in motion-induced vortex excitation is calculated as Vr = 1.67×B/D = 1.67×1.18 = 2.0 [1], vibrations around Vr = 2 were considered to be motion-induced vortex excitation. According to the smoke flow visualization result for B/D = 1.18 which was carried out by the authors, no secondary vortices at the trailing edge were formed, although separated vortices from the leading edge were formed at the time of oscillation at the onset wind speed of motion-induced vortex excitation, where aerodynamic vibrations considered to be motion-induced vortex excitation were confirmed. It was suggested that motion-induced vortex excitation might possibly occur in the range of low wind speeds, even in the case of side ratios where secondary vortices at trailing edge were not confirmed. In this study, smoke flow visualizations were performed for ratios of B/D = 0.5–2.0 in order to find out the relation between side ratios of rectangular cross sections and secondary vortices at trailing edge in motion-induced vortex excitation. The smoke flow visualizations around the model during oscillating condition were conducted in a small-sized wind tunnel at Kyushu Institute of Technology. Experimental Reynolds number was Re = VD/v = 1.6×103. For the forced-oscillating amplitude η, the non-dimensional double amplitudes were set as 2η/D = 0.02–0.15. Spring-supported tests were also carried out in order to obtain the response characteristics of the models.

scholarly journals The Characteristics of West Season Wind and Wave as well as Their Impacts on Ferry Cruise in The Kalianget-Kangean Cruise Route, Madura, Indonesia

2021 ◽  
Vol 29 (3) ◽  
Author(s):  
Viv Djanat Prasita ◽  
Lukman Aulia Zati ◽  
Supriyatno Widagdo
Keyword(s):  
Wind Speed ◽  
Wave Height ◽  
The West ◽  
Wind Speeds ◽  
Wave Patterns ◽  
Time Stamps ◽  
The Mean ◽  
Two Peaks ◽  
The Impact ◽  
Descriptive Statistical Analysis

The wind and wave conditions in the waters of the Kalianget-Kangean cruise route in the west season are relatively high so that these winds and waves can have a dangerous impact on that cruise route. The aim of this research was to analyze the characteristics of wind speed and wave height over a 10 year period (2008-2017), as well as to evaluate the weekly patterns for three months (December 2017-February 2018). These time stamps represent the west season in waters at Kalianget-Kangean route, and to identify the impact of winds and wave on this path. The method used in this research is descriptive statistical analysis to obtain the mean and maximum values ​​of wind speed and wave height. Wind and wave patterns were analyzed by WRPlot and continued with mapping of wind and wave patterns in the waters of Kalianget-Kangean and its surroundings. The data used was obtained from the Meteorology, Climatology and Geophysics Agency. The results show wind and wave characteristics with two peaks formed regularly between 2008-2017, marking the west and east monsoons. In addition, the wind speed and wave height were generally below the danger threshold, ie <10 knots and <2 m, respectively. However, there are exceptions in the west season, especially at the peak in January, where the forces are strengthened with a steady blowing direction. The maximum wind speed reaches and wave height reaches 29 knots and 6.7 m, respectively. The weekly conditions for both parameters from December 2017 to February 2018 were relatively safe, for sailing. Moreover, January 23-29, 2018 featured extreme conditions estimated as dangerous for cruise due to the respective maximum values of 25 knots and 3.8 m recorded. The channel is comparably safe, except during the western season time in December, January, February, characterized by wind speeds and wave height exceeding 21 knots and 2.5 m, correspondingly.

scholarly journals The Protect Air Film of an Exterior Window

2021 ◽  
Author(s):  
Sanaz Dianat
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Speed ◽  
Glass Temperature ◽  
Experimental Procedure ◽  
Wind Speeds ◽  
Computational Fluid Dynamics Cfd ◽  
Air Film ◽  
The Impact

The research paper investigates the impact of a window’s exterior air film on the assembly temperature. The exterior air film constitutes a vital portion of a window’s insulating values. The air film increases the temperature of the window exterior pane to a temperature above ambient temperature. The air film also rises the interior glass temperature and reduces the heat transfer from the interior surface. According to computational fluid dynamics (CFD), the air film is removed in windy conditions, decreasing the window temperature on the outside as well as on the inside. The idea behind the project is to carry out an experimental procedure on three different windows to validate the CFD results, which indicates the effect of various wind speeds. Keyword: Exterior air film, computational fluid dynamics, window assembly, wind speed

scholarly journals The Protect Air Film of an Exterior Window

2021 ◽  
Author(s):  
Sanaz Dianat
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Speed ◽  
Glass Temperature ◽  
Experimental Procedure ◽  
Wind Speeds ◽  
Computational Fluid Dynamics Cfd ◽  
Air Film ◽  
The Impact

The research paper investigates the impact of a window’s exterior air film on the assembly temperature. The exterior air film constitutes a vital portion of a window’s insulating values. The air film increases the temperature of the window exterior pane to a temperature above ambient temperature. The air film also rises the interior glass temperature and reduces the heat transfer from the interior surface. According to computational fluid dynamics (CFD), the air film is removed in windy conditions, decreasing the window temperature on the outside as well as on the inside. The idea behind the project is to carry out an experimental procedure on three different windows to validate the CFD results, which indicates the effect of various wind speeds. Keyword: Exterior air film, computational fluid dynamics, window assembly, wind speed

Effect of Nozzle Angleson Spray Losses Reduction

2014 ◽  
Vol 564 ◽  
pp. 216-221
Author(s):  
Nasir S. Hassen ◽  
Nor Azwadi Che Sidik ◽  
Jamaluddin Md Sheriff
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Mean Value ◽  
The Other ◽  
Spray Drift ◽  
Spray Application ◽  
Application Process ◽  
Nozzle Height ◽  
Wind Speeds ◽  
Flat Fan Nozzle

Spray losses are the most important problem that is faced in the spray application process as result of spray drift to non target areas by the action of air flow.This paper investigated the spray drift for banding applicationusing even flat-fan nozzle TPEunder wind tunnel conditions.In addition, this paper also examined the effect of different spray fan angles 65°, 80° and 95° on spray drift particularly where there is need to make the nozzle operate at the optimum heights above the ground or plant level.In addition, three cross wind speeds 1, 2 and 3m/swere produced to determine the effect of wind speed on total spray drift.According to the results from this study, the nozzle anglehas a significant effect on the total spray drift. The nozzle angle 65° gave the highest drift reduction compared to the other nozzle angles. The maximum driftfor all nozzles was found at nozzle height of 60 cm. The minimum mean value of the drift was found at wind speed of 1 m/s. This study supports the use of nozzle angles of less than 95° on heights more than 0.5m and on wind speeds more than 1m/s as a means for minimizing spray drift.

scholarly journals Investigation of the Superposition Effect of Oil Vapor Leakage and Diffusion from External Floating-Roof Tanks Using CFD Numerical Simulations and Wind-Tunnel Experiments

Processes ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 299
Author(s):  
Jie Fang ◽  
Weiqiu Huang ◽  
Fengyu Huang ◽  
Lipei Fu ◽  
Gao Zhang
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Simulation Method ◽  
Vapor Concentration ◽  
Monitoring And Control ◽  
Wind Tunnel Experiments ◽  
Ambient Wind ◽  
Wind Speeds ◽  
High Concentrations ◽  
And Control

Based on computational fluid dynamics (CFD) and Realizable k-ε turbulence model, we established a numerical simulation method for wind and vapor-concentration fields of various external floating-roof tanks (EFRTs) (single, two, and four) and verified its feasibility using wind-tunnel experiments. Subsequently, we analysed superposition effects of wind speed and concentration fields for different types of EFRTs. The results show that high concentrations of vapor are found near the rim gap of the floating deck and above the floating deck surface. At different ambient wind speeds, interference between tanks is different. When the ambient wind speed is greater than 2 m/s, vapor concentration in leeward area of the rear tank is greater than that between two tanks, which makes it easy to reach explosion limit. It is suggested that more monitoring should be conducted near the bottom area of the rear tank and upper area on the left of the floating deck. Superposition in a downwind direction from the EFRTs becomes more obvious with an increase in the number of EFRTs; vapor superposition occurs behind two leeward tanks after leakage from four large EFRTs. Considering safety, environmental protection, and personnel health, appropriate measures should be taken at these positions for timely monitoring, and control.

scholarly journals The importance of blowing snow to halogen-containing aerosol in coastal Antarctica: influence of source region versus wind speed

2018 ◽  
Vol 18 (22) ◽  
pp. 16689-16711 ◽  
Author(s):  
Michael R. Giordano ◽  
Lars E. Kalnajs ◽  
J. Douglas Goetz ◽  
Anita M. Avery ◽  
Erin Katz ◽  
...  
Keyword(s):  
Wind Speed ◽  
Ross Sea ◽  
Source Region ◽  
Ice Cores ◽  
Blowing Snow ◽  
Aerosol Composition ◽  
Austral Spring ◽  
Back Trajectories ◽  
Wind Speeds ◽  
The Impact

Abstract. A fundamental understanding of the processes that control Antarctic aerosols is necessary in determining the aerosol impacts on climate-relevant processes from Antarctic ice cores to clouds. The first in situ observational online composition measurements by an aerosol mass spectrometer (AMS) of Antarctic aerosols were only recently performed during the Two-Season Ozone Depletion and Interaction with Aerosols Campaign (2ODIAC). 2ODIAC was deployed to sea ice on the Ross Sea near McMurdo Station over two field seasons: austral spring–summer 2014 and winter–spring 2015. The results presented here focus on the overall trends in aerosol composition primarily as functions of air masses and local meteorological conditions. The results suggest that the impact of long-range air mass back trajectories on either the absolute or relative concentrations of the aerosol constituents measured by (and inferred from) an AMS at a coastal location is small relative to the impact of local meteorology. However, when the data are parsed by wind speed, two observations become clear. First, a critical wind speed is required to loft snow from the surface, which, in turn, increases particle counts in all measured size bins. Second, elevated wind speeds showed increased aerosol chloride and sodium. Further inspection of the AMS data shows that the increased chloride concentrations have more of a “fast-vaporizing” nature than chloride measured at low wind speed. Also presented are the Cl:Na ratios of snow samples and aerosol filter samples, as measured by ion chromatography, as well as non-chloride aerosol constituents measured by the AMS. Additionally, submicron aerosol iodine and bromine concentrations as functions of wind speed are also presented. The results presented here suggest that aerosol composition in coastal Antarctica is a strong function of wind speed and that the mechanisms determining aerosol composition are likely linked to blowing snow.

Wind tunnel tests on the characteristics of wind fields over a simplified gorge

2016 ◽  
Vol 20 (10) ◽  
pp. 1599-1611 ◽  
Author(s):  
Peng Hu ◽  
Yongle Li ◽  
Yan Han ◽  
CS Cai ◽  
Guoji Xu
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Wind Direction ◽  
Wind Field ◽  
Small Range ◽  
Wind Fields ◽  
Wind Speeds ◽  
Mean Wind Speed ◽  
Wind Characteristics ◽  
The Mean

Characteristics of wind fields over the gorge or valley terrains are becoming more and more important to the structural wind engineering. However, the studies on this topic are very limited. To obtain the fundamental characteristics information about the wind fields over a typical gorge terrain, a V-shaped simplified gorge, which was abstracted from some real deep-cutting gorges where long-span bridges usually straddle, was introduced in the present wind tunnel studies. Then, the wind characteristics including the mean wind speed, turbulence intensity, integral length scale, and the wind power spectrum over the simplified gorge were studied in a simulated atmospheric boundary layer. Furthermore, the effects of the oncoming wind field type and oncoming wind direction on these wind characteristics were also investigated. The results show that compared with the oncoming wind, the wind speeds at the gorge center become larger, but the turbulence intensities and the longitudinal integral length scales become smaller. Generally, the wind fields over the gorge terrain can be approximately divided into two layers, that is, the gorge inner layer and the gorge outer layer. The different oncoming wind field types have remarkable effects on the mean wind speed ratios near the ground. When the angle between the oncoming wind and the axis of the gorge is in a certain small range, such as smaller than 10°, the wind fields are very close to those associated with the wind direction of 0°. However, when the angle is in a larger range, such as larger than 20°, the wind fields in the gorge will significantly change. The research conclusions can provide some references for civil engineering practices regarding the characteristics of wind fields over the real gorge terrains.

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