Effect Of Wind Direction Research Articles

Wind Tunnel Test of Snow Redistribution on Roofs

A series of wind tunnel tests were carried out to predict snow distribution on roofs. A typical stepped roof and two gable roofs were investigated. Model snow depth distributions on the roofs were measured at various time intervals. The effects of velocity and wind direction were studied, and mass transport rates on the roofs were examined as well. The results show that, the saltation of particles decreases the turbulence intensity nearby the surface, and the effective aerodynamic roughness-lengths of the field are proportional to the 2nd power of the friction velocities. At the wind direction of 0°, the snow depth distribution on the stepped roof is well consistent with the field observation. Snow depth distributions on the stepped roof are quite unbalanced under oblique winds, especially at wind direction of 135°, the snow depth coefficients range from 0 to 1.7. The leeward side of the gable roofs may accumulate more snow at wind direction of 0°. The maximum coefficients are 1.7 and 1.2 for slope 10° and 20° respectively. The mean mass flux rates on the roofs are proportional to velocities, implying that the mass transport rate increases with the 3rd power of the friction velocity.

Assessing the risk of downwind spread of avian influenza virus via airborne particles from an urban wholesale poultry market

Interspecies transmissions of avian influenza viruses (AIV) occur at the human-poultry interface, among which the live poultry markets (LPMs) are easily assessed by urban residents. Thousands of live poultry from different farms arrive daily at wholesale markets before being sold to retail markets. We assessed the risk of AIV downwind spread via airborne particles from a representative wholesale market in Guangzhou. Air samples were collected using the cyclone-based NIOSH bioaerosol samplers at different locations inside a wholesale market, and viral RNA and avian 18S RNA were quantified using quantitative real-time RT-PCR. Computational Fluid Dynamics (CFD) modeling was performed to investigate the AIV spread pattern. Viral RNA was readily detected from 19 out of 21 air sampling events, predominantly from particles larger than 1 μm. The concentration of viral RNA detected at the poultry holding area was 4.4 × 105 copies/m3 and was as high as 2.6 × 104 copies/m3 100 m downwind. A high concentration of avian 18S RNA (2.5 × 108 copies/m3) detected at the poultry holding area was used for assessing the potential spread of avian influenza virus during outbreak situations. CFD modeling indicated the combined effect of wind direction and surrounding buildings on the spread of virus and a slow decay rate of the virus in the air in the downwind direction. Because of the large volume of poultry trade daily, wholesale markets located in urban areas may pose considerable AIV infection risk to neighboring residents via wind spread, even in the absence of direct contact with poultry.

Measurements and modeling of airing through porches of a historical church

In churches, intentional airing may be a measure to evacuate temporarily high levels of contaminants, emitted during services. Crucial contaminants include moisture and other emissions that may deteriorate and/or soil painted surfaces and other precious artefacts. Most old churches do not have any mechanical ventilation system or any purpose provided openings for natural ventilation, but the ventilation is governed by air infiltration. Enhanced airing may be achieved by opening external windows or doors. Thus, models provided in energy simulation programs should predict this kind of airflows correctly, to get a proper estimation of the total energy use. IDA indoor climate and energy (IDA-ICE) simulation program is examined here and its model for airflow through large vertical openings is investigated. Moreover, field measurements were performed for airing rate in a historical church. The simulated single-sided flows were of the same magnitude of the measured ones, but the effect of wind direction was less considered by the simulation program. At cross-flow, when wind is approaching the opening it has a choice; flow through the opening or around and above the building. This process is not considered in the IDA-indoor climate and energy model, which can contribute to the discrepancy between measurements and predictions.

The effect of wind direction on the performance of solar PV plants

The impact of wind direction on the overall performance of a utility-scale PV plant was studied by analyzing field data from Hadley solar farm in the UK. The solar PV plant utilizes a fixed-tilt system with the PV panels facing south at a 20 degree angle. The hypothesis is that when wind blows from the south the total power production of the solar PV plant increases in comparison with non-southerly wind events, provided that all other determining factors, such as solar irradiance, ambient temperature, and wind speed are the same. During the case study of January 1 to July 1, 2017, 42 pairs were identified, each of which includes two cases with equal solar irradiance, equal ambient temperature, and equal wind speeds but different wind directions; in one case wind is from the north and in the other one wind blows from the south. The hypothesis was found to be true across all 42 pairs, i.e., the power production of the solar PV plant was always greater in the event of southerly winds. One takeaway from this finding is that wind direction and wind speed frequencies need to be taken into account along with other climatic factors to have an optimal site selection for establishing a solar PV plant. The more frequent the southerly wind occurs, the more power can be extracted from the PV panels. The other practical conclusion of this study is that it is more efficient to build fixed-tilt solar PV plants on areas oriented along the west-east direction.

Effect of natural ventilation mode on thermal comfort and ventilation performance: Full-scale measurement

Natural ventilation can provide building occupants with thermal comfort and a healthy indoor environment. Among all the design related parameters that affect ventilation performance, ventilation mode (i.e. single-sided and cross ventilation) is perhaps the main one. The current study uses full-scale in-situ measurements to investigate the effect of ventilation mode on thermal comfort and ventilation performance of a high-rise case study unit. Two modes of natural ventilation, single-sided and cross ventilation, are investigated. Air velocity, temperature and relative humidity were measured for both ventilation modes on two consecutive days in summer. Indoor thermal conditions were evaluated using the extended Predicted Mean Vote (PMV) and Standard Effective Temperature (SET*) comfort models. In addition, the relationship between reference wind speed and internal airflow, airflow distribution, and the effect of wind direction on internal airflow were investigated for both single-sided and cross ventilation. Finally, the implications of the research outcomes on natural ventilation design are discussed. Indoor thermal conditions were found to be within the comfort zone for more than 70% of the time under cross ventilation operation while single-sided ventilation provided adequate thermal conditions for only 1% of the time. Results from this study highlight a significantly better performance of cross ventilation over single-sided ventilation.

Performance analysis of perovskite and dye-sensitized solar cells under varying operating conditions and comparison with monocrystalline silicon cell

The efficiency of solar cell is generally defined at standard test conditions. However, wind direction, wind velocity, tilt angle of panel and solar radiation during operation differ from those at standard test conditions. The effects of operating conditions on the temperature and efficiency of silicon solar cells are widely analysed in literature. In the current work, the thermal performance of perovskite and dye-sensitized solar cells in operating conditions has been analysed and compared with monocrystalline silicon solar cell. The effects of wind direction (wind azimuth angle), wind velocity, tilt angle of panel and solar radiation on the temperature and efficiency of the cells have been analysed. The results show that as wind azimuth angle increases from 0° to 90°, the temperature of the cell increases from 51.8°C to 58.2°C for monocrystalline silicon, from 45.5°C to 50.7°C for perovskite and from 48.4°C to 53.9°C for dye-sensitized solar cell and the corresponding efficiency of the cell decreases from 22.3% to 21.5% for monocrystalline silicon, from 20.1% to 19.5% for perovskite and from 11.8% to 11.7% for dye-sensitized solar cell.

A Weibull and finite mixture of the von Mises distribution for wind analysis in Mersing, Malaysia

ABSTRACTStudies of wind direction receive less attention than that of wind speed; however, wind direction affects daily activities such as shipping, the use of bridges, and construction. This research aims to study the effect of wind direction on generating wind power. A finite mixture model of the von Mises distribution and Weibull distribution are used in this paper to represent wind direction and wind speed data, respectively, for Mersing (Malaysia). The suitability of the distribution is examined by the R2 determination coefficient. The energy analysis, that is, wind power density, only involves the wind speed, but the wind direction is vital in measuring the dominant direction of wind so that the sensor could optimize wind capture. The result reveals that the estimated wind power density is between 18.2 and 25 W/m2, and SSW is the most common wind direction for this data.

Air infiltration induced inter-unit dispersion and infectious risk assessment in a high-rise residential building.

Identifying possible airborne transmission routes and assessing the associated infectious risks are essential for implementing effective control measures. This study focuses on the infiltration-induced inter-unit pollutant dispersion in a high-rise residential (HRR) building. The outdoor wind pressure distribution on the building facades was obtained from the wind tunnel experiments. And the inter-household infiltration and tracer gas transmission were simulated using multi-zone model. The risk levels along building height and under different wind directions were examined, and influence of component leakage area was analysed. It is found that, the cross-infection risk can be over 20% because of the low air infiltration rate below 0.7 ACH, which is significantly higher than the risk of 9% obtained in our previous on-site measurement with air change rate over 3 ACH. As the air infiltration rate increases along building height, cross-infection risk is generally higher on the lower floors. The effect of wind direction on inter-unit dispersion level is significant, and the presence of a contaminant source in the windward side results in the highest cross-infection risks in other adjacent units on the same floor. Properly improving internal components tightness and increasing air change via external components are beneficial to the control of internal inter-unit transmission induced by infiltration. However, this approach may increase the cross-infection via the external transmission, and effective control measures should be further explored considering multiple transmission routes.

Performance analysis of tilted photovoltaic system integrated with phase change material under varying operating conditions

In photovoltaic (PV) cells, a large fraction of solar radiation gets converted into heat which raises its temperature and decreases its efficiency. The heat can be extracted by attaching a box containing phase change material (PCM) behind the PV panel. Due to large latent heat of PCM, it can absorb heat without rise in temperature. It will lower down the PV temperature and will increase its efficiency. The available numerical studies analysed the vertical PV-PCM systems. However, PV panels are generally tilted according to latitude of the place. Thus, in the current work, performance analysis of the tilted PV-PCM is carried out. The effects of tilt-angle, wind-direction, wind-velocity, ambient-temperature and melting-temperature of PCM on the rate of heat extraction by PCM, melting process of PCM and temperature of PV-PCM system are also studied. The results show that as tilt-angle increases from 0° to 90°, the PV temperature (in PV-PCM system) decreases from 43.4 °C to 34.5 °C which leads to increase in PV efficiency from 18.1% to 19%. The comparison of PV-PCM with only-PV is also carried out and it is found that PV temperature can be reduced by 19 °C by using PCM and efficiency can be improved from 17.1% to 19%.

Effects of wind speed and direction on monthly fluctuations of Cladosporium conidia concentration in the air

This study determined the relationship between airborne concentration of Cladosporium spp. spores and wind speed and direction using real data (local wind measured by weather station) and modelled data (air mass flow computed with the aid of HYbrid Single Particle Lagrangian Trajectory model). Air samples containing fungal conidia were taken at an urban site (Worcester, UK) for a period of five consecutive years using a spore trap of the Hirst design. A threshold of ≥6000 s m−3 (double the clinical value) was applied in order to select high spore concentration days, when airborne transport of conidia at a regional scale was more likely to occur. Collected data were then examined using geospatial and statistical tools, including circular statistics. Obtained results showed that the greatest numbers of spore concentrations were detected in July and August, when C. herbarum, C. cladosporioides and C. macrocarpum sporulate. The circular correlation test was found to be more sensitive than Spearman’s rank test. The dominance of either local wind or the air mass on Cladosporium spore distributions varied between examined months. Source areas of this pathogen had an origin within the UK territory. Very high daily mean concentrations of Cladosporium spores were observed when daily mean local wind speed was vs ≤ 2.5 m s−1 indicating warm days with a light breeze.

A micro-climatic study on cooling effect of an urban park in a hot and humid climate

The cooling effect of a 4.5ha urban forest park located in a dense city center area in a hot and humid climate was investigated with the three-dimensional microclimate simulation tool ENVI-met v3.1. Dynamic predictions are firstly performed with different wind directions (northerly, southerly, easterly and westerly) for a typical summer day. Then the meteorological data were averaged to eliminate the effect of wind direction, considering equal probability for each wind direction. Overall, when wind speed is 1.5m/s, park cool island (PCI) intensity is about 2°C and the PCI center is offset from the park center if a preponderant prevailing wind direction exists. After eliminating the influence of wind direction by considering equal probability for each wind direction, PCI intensity is about 0.8°C and the PCI center is near to the park center. A higher wind speed would lead to a lower PCI intensity and a smaller area of influence. Compared to air temperature, the spatial distributions of mean radiant temperature and relative humidity are not significantly affected by a preponderant prevailing wind direction. And mean radiant temperature was found to be about 30°C lower in shaded areas of the park.

Air and Soil Concentrations and Source Identification of Ambient Polychlorinated Biphenyls in the Northeastern Mediterranean Region

Ambient air and soil samples were taken in Istanbul between November 2012 and May 2013 in order to determine polychlorinated biphenyl (PCB) concentrations. A high volume air sampler was operated to collect air samples. Soil samples were taken from top of bare land. Air PCB concentrations ranged from 201 to 705 pg m−3 with an average of 360 pg m−3. The dry weight soil PCB concentrations varied from 3.4 to 13.6 ng g−1 with an average of 8.3 ng g−1. The fate of PCBs was investigated through gas/particle partitioning. Further investigation was made between soil and air phases by fugacity fractions. Effect of wind direction was revealed by conditional probability function (CPF). Potential source contribution function was employed to determine the likely distant PCB sources. Di‐chlorinated biphenyls (Di‐CBs) tended to accumulate in soil while 5‐, 7‐, and 8‐CBs volatilized from the soil. According to CPF, 3‐CBs were likely to be released from the Marmara Sea. Additionally, SW wind direction was dominant for Σ‐, 2‐, 5‐, 6‐, 7‐CBs, and concentration of 9‐CBs increased for the winds of NW, N, NE directions. Previously reported hot‐spot zones for iron‐steel manufacturing industry were identified to contribute to PCBs in air masses, arriving from SW direction. Additional contribution was detected when air masses arrived from the north. These sources were from the south of the Ukraine.

Hour-ahead wind power forecast based on random forests

Due to its chaotic nature, the wind behavior is difficult to forecast. Predicting wind power is a real challenge for dispatchers who need to estimate renewable generation in advance to establish their strategies. To achieve an accurate wind power prediction, it is important to determine first which meteorological data need to be included in the predictor. For that purpose, this paper focuses on choosing the appropriate weather factors, namely spatially averaged wind speed and wind direction. These factors are selected according to correlation and importance measures. Then, the random forest method is proposed to build an hour-ahead wind power predictor. The random forest does not need to be tuned or optimized, contrary to most other learning machines. Both point and probabilistic forecasts are performed using the same inputs. The emphasis is put on the effect of wind speed and direction on the model performance, and the immunity of random forest to irrelevant inputs. The wind data used to test the proposed model are taken from Sidi Daoud wind farm in Tunisia. Results show an interesting improvement of forecast accuracy using the proposed model, as well as an important reduction of the different error criteria compared to classical neural network prediction.

Dynamics of water and salt exchange at Maryland Coastal Bays

The exchange processes between the Maryland Coastal Bays system (MCBs) and their adjacent coastal ocean were simulated using a three-dimensional unstructured-grid based hydrodynamic model, which was validated by observed data including water level, current velocity and salinity. Idealized experiments were then carried out to investigate the impact of wind forcing on water exchange and salt flux. Through these experiments, the exchanges between the MCBs and coastal ocean were investigated at two inlets (Ocean City Inlet and Chincoteague Inlet). Given that winds and tides are two key external forces known to impact estuarine dynamics, the effect of each individual force on the exchange processes was studied to evaluate the corresponding influence on the inlet dynamics. It was found that wind forcing significantly impacts the inlet dynamics: the effect of wind directions on exchange processes under strong wind speeds is substantial; for example, northwesterly winds push flux to the southern part of the bays, while southwesterly winds pile up flux towards northern Chincoteague Bay. The effect of wind forcing on the exchange dynamics becomes stronger with the augmentation of its speed. Meanwhile, tidal forcing is the major driver of exchange dynamics at weak wind speeds (e.g., 3 m/s), and its effect on exchange process gradually weakens with stronger wind speeds (e.g., 7 m/s, 15 m/s). In addition, sensitivity tests elucidated that closing either inlet results in a significant impact on the water elevation, current velocity and salinity nearby the relevant cut-off inlet areas.

Influence of meteorological conditions on correlation between aerosol and cloud in summer

Aerosols can affect the atmospheric radiation balance through direct and indirect effects. The formation and development of cloud and precipitation influenced by aerosols differ significantly from each other in different meteorological conditions. In this work, we used the MODIS’s daily Aerosol Optical Depth (AOD), Cloud Effective Radius (CER), Cloud Top Temperature (CTT), Cloud Water Path (CWP) and ECMWF’s Relative Humidity (RH), Vertical Velocity (VV) and Horizontal Wind (HW) (from 2005 to 2008) to reveal the influence of meteorological factors on the distribution of aerosols, and also the correlation between aerosols and clouds. The study was designed in such a way that, the RH, VV, Upwind (UW), Downwind (DW) and CWP were divided into several intervals, to quantify the relationship between AOD and CER by controlling one single variable or two comprehensive variables over the mountains and plains. At the same time, the effect of wind speed and direction on polluted conditions was analyzed through the superposed spatial distribution map of wind and AOD. The conclusions are as follows: (1) The wind coming from mountains dispelled aerosols while the sea breeze invigorated aerosols, and the upwind showed a markedly negative relevance with AOD. (2) The strong upwind contributed to the positive relationship between AOD and CER, and the correlation rose by 38% after excluding the condition where CWP<34g/m2. (3) For the horizontal wind, only the zonal wind over the plains had obvious effects on the correlation, while the meridonal wind did not show evident influence. (4) For the plains, when CWP values were within the interval of 0–34g/m2 and 74–150g/m2, the correlation was positive, while in 34–74g/m2, it was negative. However, it is generally positive either over the mountains or in clean conditions. Moreover, the influence of RH on the correlation was consistent with that of CWP.

Effects of wind, ambient temperature and sun position on damselfly flight activity and perch orientation

Many animals rely on movement for survival and reproduction. Directed movements incur metabolic costs, however, and animals adjust their behaviour to optimize energy expenditures in different abiotic conditions. Physical flows and solar radiation vary over time and space and influence animal behaviour at multiple spatiotemporal scales. Here, I quantify the effects of wind speed, wind direction, ambient temperature and sun position on the fine-scale movement ecology and perch orientation of a widespread damselfly, Enallagma doubledayi. Through field observations, I found that damselflies fly, forage and engage competitors in territorial interactions more often in calm rather than windy conditions. Furthermore, perched damselflies exhibit rheotaxis, in which individuals typically face into the wind, presumably to minimize biomechanical costs associated with drag and possibly to detect inbound prey on the water surface and in the air column. In contrast, ambient temperature and the position of the sun were largely unassociated with activity levels and damselfly orientation. At higher ambient temperatures, however, perched odonates faced the sun with increasing consistency, perhaps to thermoregulate by minimizing exposure to solar radiation. Taken together, these findings suggest that damselflies preferentially fly when the ratio of animal speed to wind speed is high and adjust their perch orientation to minimize energy loss. These findings strengthen conceptual links between activity budgets and perch orientation strategies among animals in variable abiotic conditions.

Improvement of Corona Discharge Model and Its Application on Simulating Corona Discharge in the Presence of Wind

To evaluate the effect of wind on corona discharges occurring on the tip of a grounded rod during a negative charging process of thundercloud, a two-dimensional numerical model has been improved by considering the wind velocity as a driving force for the movement of the corona charges. It was found that not only wind speed but also wind direction have a significant effect on the distribution of corona charges, the local electric field around the rod, and the corona current. (1) Under the same wind speed, a larger horizontal wind can result in less accumulation of corona charges, a larger electric field, and a larger corona current. However, when the speed is less than 5 m s−1, the effect of wind direction on the corona current was weak. (2) Under the same wind direction, a larger wind speed can cause a larger corona current. However, when the horizontal wind component is smaller than the vertical, the larger wind speed would cause a smaller electric field. Thus, it is necessary to take the effects of the wind direction into consideration, rather than to consider its speed only, when studying the corona discharge and its effects on the upward leader.

Analysis on Vortex Streets Behind a Square Cylinder at High Reynolds Number Using a Large-Eddy Simulation Model: Effects of Wind Direction, Speed, and Cylinder Width

Analysis on Vortex Streets Behind a Square Cylinder at High Reynolds Number Using a Large-Eddy Simulation Model: Effects of Wind Direction, Speed, and Cylinder Width

CARATS Open Dataを用いたレディオ空港の風速風向による着陸滑走路選択の調査

CARATS Open Dataを用いたレディオ空港の風速風向による着陸滑走路選択の調査

Experimental and numerical analysis of convective heat losses from spherical cavity receiver of solar concentrator

Spherical cavity receiver of solar concentrator is made up of Cu tubing material having cavity diameter 385 mm to analyze the different heat losses such as conduction, convection and radiation. As the convection loss plays major role in heat loss analysis of cavity receiver, the experimental analysis is carried out to study convective heat loss for the temperature range of 55-75?C at 0?, 15?, 30?, 45?, 60?, and 90? inclination angle of downward facing cavity receiver. The numerical analysis is carried out to study convective heat loss for the low temperature range (55-75?C) as well as high temperature range (150-300 ?C) for no wind condition only. The experimental set-up mainly consists of spherical cavity receiver which is insulated with glass wool insulation to reduce the heat losses from outside surface. The numerical analysis is carried out by using CFD software and the results are compared with the experimental results and found good agreement. The result shows that the convective loss increases with decrease in cavity inclination angle and decreases with decrease in mean cavity receiver temperature. The maximum losses are obtained at 0? inclination angle and the minimum losses are obtained at 90? inclination angle of cavity due to increase in stagnation zone in to the cavity from 0? to 90? inclination. The Nusselt number correlation is developed for the low temperature range 55-75?C based on the experimental data. The analysis is also carried out to study the effect of wind speed and wind direction on convective heat losses. The convective heat losses are studied for two wind speeds (3 m/s and 5 m/s) and four wind directions [? is 0? (Side-on wind), 30?, 60?, and 90? (head-on wind)]. It is found that the convective heat losses for both wind speed are higher than the losses obtained by no wind test. The highest heat losses are found for wind direction ? is 60? with respect to receiver stand and lowest heat losses are found for wind direction ? is 0? (side-on wind). The heat losses obtained for wind direction, ?, is 30? condition are higher than the heat losses obtained for wind direction ? is 0? (side-on wind) condition, while the heat losses obtained by wind direction ? is 90? (head-on wind) condition are less than the heat losses obtained for wind direction, ?, is 60? condition.