Simplified Method for Assessing Outdoor Ventilation Environment for Heat Island Relaxation

This study introduces a new method for assessing the outdoor ventilation environment in Taiwan, with a view to reducing the heat island phenomenon. The ventilation environment is important in cooling the outdoor environment, but its evaluation is very difficult and complex. Therefore, this study develops a simple method for assessing the outdoor ventilation environment, it is used in computational fluid dynamics (CFD) simulation software, only to generate numerical models using empirical building types include rectangular shape and courtyard building, then calculate their wind shadow areas (WSa). Then, many factors, such as the site plan, the size of building and local wind data are used to draw these areas to the scope of WSa. The results of the simple assessment method are verified by performing CFD simulations to corroborate the correlation between simplified assessment method and CFD simulation result, an R2value of 0.87 is obtained. The method is helpful in improving design decisions in the planning and design stage of site plan.

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Research on Assessment Method of Green Buildings in China

ASME 2010 4th International Conference on Energy Sustainability, Volume 1 ◽

10.1115/es2010-90349 ◽

2010 ◽

Author(s):

Bing Wei ◽

Bin Zhang ◽

Wen Luo

Keyword(s):

Index System ◽

Green Building ◽

Green Buildings ◽

Assessment Method ◽

Assessment System ◽

Outdoor Environment ◽

Design Stage ◽

Assessment Index ◽

Building Assessment ◽

Assessment Index System

Presently the sustainable development stratagem has made the green buildings to be a trend of building industry in China, and the assessment to the green buildings is becoming more and more important in developing the green buildings. In this paper the meaning of the green building assessment is explained, several main domestic and foreign green building assessment systems are analyzed and compared, and the common ground and limitations of these assessment methods are presented. Then a novel assessment index system which is more comprehensive, scientific and suitable for green buildings in China is developed by using the life cycle assessment method. This system contains six categories including land saving and outdoor environment, energy saving and utilization, material saving and utilization, water saving and utilization, indoor environment quality and economy. According to the decision-making stage, design stage, construction stage, operation and maintenance stage, each category is divided into more concrete indexes. At last the established assessment system is used to evaluate a typical building in Xi’an, China. The final novel assessment index system is of theoretical and practical significance for the assessment and development of green buildings in China.

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CFD simulation of flow behind overflooded obstacle

Journal of Hydrology and Hydromechanics ◽

10.2478/johh-2018-0028 ◽

2018 ◽

Vol 66 (4) ◽

pp. 448-456

Author(s):

Yvetta Velísková ◽

Zdeněk Chára ◽

Radoslav Schügerl ◽

Renáta Dulovičová

Keyword(s):

Velocity Profile ◽

Cfd Simulation ◽

Numerical Models ◽

Measured Data ◽

Ansys Fluent ◽

Laboratory Flume ◽

Rans Models ◽

Unsteady Rans ◽

Computational Fluid Dynamics Cfd ◽

Stress Models

Abstract This paper deals with studying of two topics – measuring of velocity profile deformation behind a over-flooded construction and modelling of this velocity profile deformation by computational fluid dynamics (CFD). Numerical simulations with an unsteady RANS models - Standard k-ε, Realizable k-ε, Standard k-ω and Reynolds stress models (ANSYS Fluent v.18) and experimental measurements in a laboratory flume (using ADV) were performed. Results of both approaches showed and affirmed presence of velocity profile deformation behind the obstacle, but some discrepancies between the measured and simulated values were also observed. With increasing distance from the obstacle, the differences between the simulation and the measured data increase and the results of the numerical models are no longer usable.

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Study on Hazardous Areas of Hydrogen Fluoride Diffusion Based on CFD Simulation

Processes ◽

10.3390/pr9091545 ◽

2021 ◽

Vol 9 (9) ◽

pp. 1545

Author(s):

Siyan Chen ◽

Zhengqing Zhou ◽

Yong Ma ◽

Li Zhang ◽

Tianyi Wang ◽

...

Keyword(s):

Hydrogen Fluoride ◽

Cfd Simulation ◽

Emergency Evacuation ◽

Simulation Software ◽

Rescue Work ◽

Gas Leakage ◽

Safety And Health ◽

Computational Fluid Dynamics Cfd ◽

Personnel Safety ◽

Injury Area

Hydrogen fluoride (HF) is a typical dangerous gas in the fluorine chemical industry. Its leakage is one of the most common types of accidents in this industry, and it poses a serious threat to personnel safety and health, environmental sanitation, and social stability. In this paper, the process and consequences of an HF leakage accident in a fluorine chemical plant were simulated by using computational fluid dynamics (CFD) simulation software, and hazardous areas (lethal area, severe injury area, light injury area, and maximum allowable concentration area) of HF diffusion were determined according to the HF concentration corresponding to the degree of personal injury. Moreover, the effects of wind speed and height on hazardous areas were analyzed. The research results of this paper provide model support for similar enterprises to predict the consequences of harmful gas leakage accidents, and give suggestions on emergency evacuation and rescue work, which have practical application significance.

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TINJAUAN TERHADAP STRATEGI PENGHAWAAN RUANG PERKOTAAN MELALUI ATAP HIJAU

Jurnal Penelitian dan Karya Ilmiah Arsitektur Usakti ◽

10.25105/agora.v16i02.3231 ◽

2018 ◽

Vol 16 (02) ◽

pp. 76

Author(s):

M Donny Kurniawan ◽

Suhendri .

Keyword(s):

Fluid Dynamics ◽

Urban Heat Island ◽

Cfd Simulation ◽

Urban Canyon ◽

Outdoor Thermal Comfort ◽

Wind Flow ◽

Heat Island ◽

Urban Heat ◽

Computational Fluid Dynamics Cfd ◽

Roof Garden

Kenyamanan termal di ruang luar menjadi isu yang penting saat ini akibat kenaikan yang signifikan pada suhu udara perkotaan. Kenaikan suhu ini diakibatkan oleh perubahan iklim global dan fenomena pulau panas perkotaan (Urban Heat Island) faktor pulau panas perkotaan ini dapat direduksi salah satunya dengan penghawaan pasif di ruang-ruang perkotaan. Dalam rancangan kota, penghawaan perkotaan dapat berupa pengaturan massa-massa bangunan, orientasi jalan, sampai ke detail desain bagunan yang dirancang untuk mengalirkan angin. Kota dengan penghawaan perkotaan yang baik dapat melepaskan panas yang terperangkap di antara bangunan melalui angin, juga dapat memberikan kenyamanan termal pada ruang luar. Penelitian ini bertujuan untuk mengetahui efektivitas strategi pengahawaan perkotaan dengan perletakan atap hijau di bangunan tinggi. Efektivitas ini ditinjau dari hasil simulasi Computational Fluid Dynamics (CFD) terhadap berbagai posisi perletakan atap hijau pada bangunan tinggi. Hasil simulasi didapat dari dua metode simulasi, yaitu CFD 3 dimensi pada skala kota dan CFD 2 dimensi pada urban canyon. Kedua simulasi tersebut menunjukkan bahwa atap hijau yang diletakkan pada posisi yang tepat di sebuah bangunan tinggi dapat memicu pergerakan angin yang potensial bagi reduksi pulau panas perkotaan sekaligus memberikan kenyamanan termal ruang luar di perkotaan. Kata kunci: kenyamanan termal ruang luar, pulau panas perkotaan, atap hijau, CFD ABSTRACTCities are facing temperature increase due to global warming and urban heat island. Although the global warming needs to be solved with global acts, the urban heat island presumably can be reduced by ventilated city strategies. Ventilated cities are designed to create a preferable wind flow in the city’s spaces. Thus, it releases heat that is trapped in the urban canyon and reduces urban heat island. Wind generated by the strategy could also provide outdoor thermal comfort in the cities. One of the ventilated city strategies are by utilizing roof garden for high rise buildings. Therefore, this research is aimed to identify the effectivity of roof garden in delivering wind flow. Two computational fluid dynamics (CFD) simulation schemes had been analyzed, and this paper reviews the results. The schemes are 3D CFD simulation for urban area and 2D CFD simulation for urban canyon. Review of the result analysis shows that roof garden is potential to drive a sufficient wind flow as long as its position is appropriate. Keywords : outdoor thermal comfort, urban heat island, roof garden, CFD

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A Rational Numerical Method for Simulation of Drop-Impact Dynamics of Oleo-Pneumatic Landing Gear

Applied Sciences ◽

10.3390/app11094136 ◽

2021 ◽

Vol 11 (9) ◽

pp. 4136

Author(s):

Rosario Pecora

Keyword(s):

Numerical Method ◽

Initial Conditions ◽

Impact Load ◽

Numerical Models ◽

Landing Gear ◽

Design Stage ◽

Impact Dynamics ◽

State Variables ◽

Adopted Model ◽

The Impact

Oleo-pneumatic landing gear is a complex mechanical system conceived to efficiently absorb and dissipate an aircraft’s kinetic energy at touchdown, thus reducing the impact load and acceleration transmitted to the airframe. Due to its significant influence on ground loads, this system is generally designed in parallel with the main structural components of the aircraft, such as the fuselage and wings. Robust numerical models for simulating landing gear impact dynamics are essential from the preliminary design stage in order to properly assess aircraft configuration and structural arrangements. Finite element (FE) analysis is a viable solution for supporting the design. However, regarding the oleo-pneumatic struts, FE-based simulation may become unpractical, since detailed models are required to obtain reliable results. Moreover, FE models could not be very versatile for accommodating the many design updates that usually occur at the beginning of the landing gear project or during the layout optimization process. In this work, a numerical method for simulating oleo-pneumatic landing gear drop dynamics is presented. To effectively support both the preliminary and advanced design of landing gear units, the proposed simulation approach rationally balances the level of sophistication of the adopted model with the need for accurate results. Although based on a formulation assuming only four state variables for the description of landing gear dynamics, the approach successfully accounts for all the relevant forces that arise during the drop and their influence on landing gear motion. A set of intercommunicating routines was implemented in MATLAB® environment to integrate the dynamic impact equations, starting from user-defined initial conditions and general parameters related to the geometric and structural configuration of the landing gear. The tool was then used to simulate a drop test of a reference landing gear, and the obtained results were successfully validated against available experimental data.

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Review on Urban Heat Island in China: Methods, Its Impact on Buildings Energy Demand and Mitigation Strategies

Sustainability ◽

10.3390/su13020762 ◽

2021 ◽

Vol 13 (2) ◽

pp. 762

Author(s):

Liu Tian ◽

Yongcai Li ◽

Jun Lu ◽

Jue Wang

Keyword(s):

Energy Consumption ◽

Urban Heat Island ◽

Building Energy ◽

Design Stage ◽

Heat Island ◽

Building Energy Consumption ◽

Rapid Urbanization ◽

Substantial Impact ◽

Urban Heat ◽

The Impact

High population density, dense high-rise buildings, and impervious pavements increase the vulnerability of cities, which aggravate the urban climate environment characterized by the urban heat island (UHI) effect. Cities in China provide unique information on the UHI phenomenon because they have experienced rapid urbanization and dramatic economic development, which have had a great influence on the climate in recent decades. This paper provides a review of recent research on the methods and impacts of UHI on building energy consumption, and the practical techniques that can be used to mitigate the adverse effects of UHI in China. The impact of UHI on building energy consumption depends largely on the local microclimate, the urban area features where the building is located, and the type and characteristics of the building. In the urban areas dominated by air conditioning, UHI could result in an approximately 10–16% increase in cooling energy consumption. Besides, the potential negative effects of UHI can be prevented from China in many ways, such as urban greening, cool material, water bodies, urban ventilation, etc. These strategies could have a substantial impact on the overall urban thermal environment if they can be used in the project design stage of urban planning and implemented on a large scale. Therefore, this study is useful to deepen the understanding of the physical mechanisms of UHI and provide practical approaches to fight the UHI for the urban planners, public health officials, and city decision-makers in China.

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Computational fluid dynamics (CFD) simulation analysis on retinal gas cover rates using computational eye models

Scientific Reports ◽

10.1038/s41598-021-84574-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Makoto Gozawa ◽

Yoshihiro Takamura ◽

Tomoe Aoki ◽

Kentaro Iwasaki ◽

Masaru Inatani

Keyword(s):

Cfd Simulation ◽

Simulation Analysis ◽

Fluid Dynamic ◽

Fluid Analysis ◽

Intraocular Gas ◽

Pars Plana ◽

Computational Fluid Dynamics Cfd ◽

Multiple Breaks ◽

Gas Volume ◽

Wall Wettability

AbstractWe investigated the change in the retinal gas cover rates due to intraocular gas volume and positions using computational eye models and demonstrated the appropriate position after pars plana vitrectomy (PPV) with gas tamponade for rhegmatogenous retinal detachments (RRDs). Computational fluid dynamic (CFD) software was used to calculate the retinal wall wettability of a computational pseudophakic eye models using fluid analysis. The model utilized different gas volumes from 10 to 90%, in increments of 10% to the vitreous cavity in the supine, sitting, lateral, prone with closed eyes, and prone positions. Then, the gas cover rates of the retina were measured in each quadrant. When breaks are limited to the inferior retina anterior to the equator or multiple breaks are observed in two or more quadrants anterior to the equator, supine position maintained 100% gas cover rates in all breaks for the longest duration compared with other positions. When breaks are limited to either superior, nasal, or temporal retina, sitting, lower temporal, and lower nasal position were maintained at 100% gas cover rates for the longest duration, respectively. Our results may contribute to better surgical outcomes of RRDs and a reduction in the duration of the postoperative prone position.

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Computational fluid dynamics (CFD) simulation of flow in the rotary drum for pyrite bio-preoxidization

Chemical Engineering and Processing - Process Intensification ◽

10.1016/j.cep.2007.03.011 ◽

2008 ◽

Vol 47 (5) ◽

pp. 971-978 ◽

Cited By ~ 5

Author(s):

T. Liu ◽

X. Qi ◽

G. Su ◽

J. Jin ◽

W. Cong

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Cfd Simulation ◽

Computational Fluid Dynamics Cfd ◽

Rotary Drum

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Numerical Investigation for the Resin Filling Behavior during Ultraviolet Nanoimprint Lithography of Subwavelength Moth-Eye Nanostructure

Coatings ◽

10.3390/coatings11070799 ◽

2021 ◽

Vol 11 (7) ◽

pp. 799

Author(s):

Yuanchi Cui ◽

Xuewen Wang ◽

Chengpeng Zhang ◽

Jilai Wang ◽

Zhenyu Shi

Keyword(s):

Simulation Model ◽

Nanoimprint Lithography ◽

Cfd Simulation ◽

Boundary Slip ◽

Accurate Analysis ◽

Inlet Velocity ◽

Filling Height ◽

Proposed Model ◽

Good Consistency ◽

Computational Fluid Dynamics Cfd

Accurate analysis of the resin filling process into the mold cavity is necessary for the high-precision fabrication of moth-eye nanostructure using the ultraviolet nanoimprint lithography (UV-NIL) technique. In this research, a computational fluid dynamics (CFD) simulation model was proposed to reveal resin filling behavior, in which the effect of boundary slip was considered. By comparison with the experimental results, a good consistency was found, indicating that the simulation model could be used to analyze the resin filling behavior. Based on the proposed model, the effects of process parameters on resin filling behavior were analyzed, including resin viscosity, inlet velocity and resin thickness. It was found that the inlet velocity showed a more significant effect on filling height than the resin viscosity and thickness. Besides, the effects of boundary conditions on resin filling behavior were investigated, and it was found the boundary slip had a significant influence on resin filling behavior, and excellent filling results were obtained with a larger slip velocity on the mold side. This research could provide guidance for a more comprehensive understanding of the resin filling behavior during UV-NIL of subwavelength moth-eye nanostructure.

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