scholarly journals Green Façade Effects on Thermal Environment in Transitional Space: Field Measurement Studies and Computational Fluid Dynamics Simulations

2019 ◽  
Vol 11 (20) ◽  
pp. 5691 ◽  
Author(s):  
Hankun Lin ◽  
Yiqiang Xiao ◽  
Florian Musso ◽  
Yao Lu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Thermal Environment ◽  
Traffic Noise ◽  
Field Measurements ◽  
Simulation Method ◽  
Urban Heat Islands ◽  
Transitional Space ◽  
Humid Climate ◽  
Dynamics Simulations

High-density urban development areas have several problems associated with them, such as the formation of urban heat islands, traffic noise, and air pollution. To minimize these problems, the green façades (GFs), which are used to guide climbing plants to grow vertically on building facade, are focused on by researchers and architects. This study focuses on GF application strategies and their optimizations for thermal comfort in a transitional space in a hot-humid climate. First, field measurements were collected from GF projects located in Guangzhou, China, in summer 2017. Second, a simulation method using computational fluid dynamics (CFD) was used to investigate the thermal effects of the GF’s foliage. Finally, seven GF typologies and one unshaded comparison model were used for simulations in three scenarios with south, east, and west orientations and compared to evaluate the effects of GFs on the thermal environment of the transitional space. The results of field measurements reveal that the GF reduced average Physiologically Equivalent Temperature (PET) by 2.54 °C, and that of CFD simulations reveal that three typologies of GFs are more effective in regulating the thermal environment in the summer. The results of this research provide support for further studies on the thermal effectiveness and design options of GFs for human comfort.

scholarly journals Computational Fluid Dynamics-Based Simulation of Crop Canopy Temperature and Humidity in Double-Film Solar Greenhouse

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Wei Jiao ◽  
Qi Liu ◽  
Lijun Gao ◽  
Kunyu Liu ◽  
Rui Shi ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Porous Medium ◽  
Canopy Temperature ◽  
Simulation Method ◽  
Solar Greenhouse ◽  
Temperature And Humidity ◽  
Carbon Dioxide Detection ◽  
Dynamics Simulations ◽  
Mean Square Errors

The microenvironment of the crop area in a greenhouse is the main factor that affects its growth, quality, and pest control. In this study, we propose a double-layer film solar greenhouse microenvironment testing system based on computational fluid dynamics simulations of a celery canopy with a porous medium. A real greenhouse was examined with a sensor system for soil, air, radiation, and carbon dioxide detection to verify the simulation results. By monitoring the internal environment of celery canopies with heights of 0.8 and 1 m during a period of temperature fluctuations, we found the temperature and humidity of the canopy interior changed spatially and differed greatly from the those in the greenhouse under solar radiation conditions. The temperature and humidity of the celery canopy were 4–14°C lower and 10%–30% higher than those of the surroundings. As the canopy grew, the differences in temperature and humidity between the canopy and other parts of the greenhouse increased. The root mean square errors of the temperature and humidity with the 0.8 m high celery canopy were found to be 0.56 and 2.86 during the day and 0.24 and 0.81 at night, respectively; the corresponding values for the 1 m high celery canopy were found to be 0.51 and 2.26 during the day and 0.26 and 0.78 at night. The porous medium model expressed the temperature and humidity characteristics of the celery crop appropriately, and the simulation method was shown to be effective and feasible. With the simulation method proposed in this study, the production of crops in complex microenvironments in greenhouses can be modeled and digitized.

scholarly journals Aerodynamic analysis of uphill drafting in cycling

2021 ◽  
Vol 24 (1) ◽  
Author(s):  
T. van Druenen ◽  
B. Blocken
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Speed ◽  
Scientific Literature ◽  
Sensitivity Analyses ◽  
Air Resistance ◽  
Wind Tunnel Measurements ◽  
Aerodynamic Effect ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

AbstractSome teams aiming for victory in a mountain stage in cycling take control in the uphill sections of the stage. While drafting, the team imposes a high speed at the front of the peloton defending their team leader from opponent’s attacks. Drafting is a well-known strategy on flat or descending sections and has been studied before in this context. However, there are no systematic and extensive studies in the scientific literature on the aerodynamic effect of uphill drafting. Some studies even suggested that for gradients above 7.2% the speeds drop to 17 km/h and the air resistance can be neglected. In this paper, uphill drafting is analyzed and quantified by means of drag reductions and power reductions obtained by computational fluid dynamics simulations validated with wind tunnel measurements. It is shown that even for gradients above 7.2%, drafting can yield substantial benefits. Drafting allows cyclists to save over 7% of power on a slope of 7.5% at a speed of 6 m/s. At a speed of 8 m/s, this reduction can exceed 16%. Sensitivity analyses indicate that significant power savings can be achieved, also with varying bicycle, cyclist, road and environmental characteristics.

scholarly journals Evaluation of Active Heat Sinks Design under Forced Convection—Effect of Geometric and Boundary Parameters

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2041
Author(s):  
Eva C. Silva ◽  
Álvaro M. Sampaio ◽  
António J. Pontes
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Additive Manufacturing ◽  
Pressure Drop ◽  
Forced Convection ◽  
Thermal Performance ◽  
Heat Sinks ◽  
Trapezoidal Shape ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

This study shows the performance of heat sinks (HS) with different designs under forced convection, varying geometric and boundary parameters, via computational fluid dynamics simulations. Initially, a complete and detailed analysis of the thermal performance of various conventional HS designs was taken. Afterwards, HS designs were modified following some additive manufacturing approaches. The HS performance was compared by measuring their temperatures and pressure drop after 15 s. Smaller diameters/thicknesses and larger fins/pins spacing provided better results. For fins HS, the use of radial fins, with an inverted trapezoidal shape and with larger holes was advantageous. Regarding pins HS, the best option contemplated circular pins in combination with frontal holes in their structure. Additionally, lattice HS, only possible to be produced by additive manufacturing, was also studied. Lower temperatures were obtained with a hexagon unit cell. Lastly, a comparison between the best HS in each category showed a lower thermal resistance for lattice HS. Despite the increase of at least 38% in pressure drop, a consequence of its frontal area, the temperature was 26% and 56% lower when compared to conventional pins and fins HS, respectively, and 9% and 28% lower when compared to the best pins and best fins of this study.

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