scholarly journals Numerical Simulation of Early Stage of a Compartment Fire

1984 ◽  
Vol 4 (2) ◽  
pp. 91-110 ◽  
Author(s):  
Takashi Handa ◽  
Kunio Kawagoe ◽  
Tomoaki Yoshikawa ◽  
Junji Mashige ◽  
Tomoko Joh
Keyword(s):  
Numerical Simulation ◽  
Early Stage ◽  
Compartment Fire

Numerical Simulation and Analysis of Compartment Fire in Subway Train

2012 ◽  
Vol 166-169 ◽  
pp. 2726-2730
Author(s):  
Bo Si Zhang ◽  
Shou Xiang Lu
Keyword(s):  
Numerical Simulation ◽  
Transport System ◽  
Fire Safety ◽  
Urban Transport ◽  
The Other ◽  
Compartment Fire ◽  
Fire Simulation ◽  
Subway Train ◽  
Simulation Time

Subway plays an important role in urban transport system. Fire as the major risk of the subway, is gaining increasing concern. In this study, fire simulation is performed to estimate fire safety of different compartments of the subway train. Result shows that the two compartments in the middle become dangerous at 150s and the compartments in the two ends are not safe at 300s approximately. The other two compartments are always safe during the simulation time.

scholarly journals The numerical simulation of Influence of Drying-wetting Cycles on the Deterioration Characteristics of Gypsum Rocks under Particle Flow Code

2020 ◽  
Vol 24 (1) ◽  
pp. 55-59
Author(s):  
Guopeng Wu ◽  
Wenwu Chen ◽  
Kai Cui
Keyword(s):  
Mechanical Properties ◽  
Numerical Simulation ◽  
Water Absorption ◽  
Absorption Rate ◽  
Early Stage ◽  
Particle Flow ◽  
Wetting And Drying ◽  
Water Absorption Rate ◽  
Gypsum Rock ◽  
Deterioration Characteristics

In order to study the influence of dry-wet cycling on the deterioration characteristics of gypsum rocks and solve the problems encountered in engineering construction, in this study, gypsum rocks are taken as the research object. With the combination of laboratory test and theoretical analysis, the numerical simulation of particle flow is carried out, and the deterioration characteristics of physical and mechanical properties of gypsum rock under dry-wet cycling are studied. The results show that gypsum, quartz, zeolite and dolomite are the main components of gypsum rocks. Gypsum occupies the most components in gypsum rocks, so the various characteristics of gypsum greatly affect the characteristics of gypsum rocks. The process of water absorption and loss of gypsum is similar, which shows that the rate of water absorption or loss of gypsum is faster in the early stage, and tends to be stable in the later stage. The curve of the whole process of water absorption and loss is fitted by negative exponential function, and the effect is better. The larger the porosity of gypsum rock is, the better its water absorption performance is. Intergranular pore, dissolution pore and dissolution pore are the main pore types of gypsum rock. Intergranular pore is the main water absorption channel of gypsum rock. The cumulative water absorption increases with the increase of wetting and drying cycles. The change of water absorption curve is mainly manifested in water absorption rate and time. The more the number of wet-dry cycles is, the higher the water absorption rate in the early stage of water absorption is, the closer the characteristic curve to the coordinate axis of water absorption is, and the shorter the water absorption time is. In contrast, the shape difference of water loss curve is very small. It can be seen from this that in the process of wetting and drying cycle, the hydrophysical and hydrochemical processes promote each other, which changes the crystal structure and pore structure of gypsum rocks, reduces the crystal strength and increases the porosity, thus leading to the deterioration of the mechanical properties of gypsum rocks.

Numerical Simulation of Temperature Profile in a Compartment Fire with a Roof Opening

2012 ◽  
Vol 538-541 ◽  
pp. 989-992 ◽  
Author(s):  
Jin Mei Li ◽  
Qiang Li ◽  
Yan Lei Dong ◽  
Chang Hai Li
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Temperature Profile ◽  
Source Size ◽  
Temperature Profiles ◽  
Compartment Fire ◽  
Gas Temperature ◽  
Fire Source ◽  
Smoke Layer ◽  
Cooling Function

Fifteen numerical simulations are presented in this article to investigate the influence of roof opening size and fire source size on gas temperature profiles in a compartment. The fire source size has a significant impact on the temperature hot smoke layer. The temperature of hot smoke layer increases as the increase of fire source size. The roof opening has cooling function to gas temperature in the compartment especially for large roof opening. The temperatures of hot smoke layer decrease with the roof opening size increase in all cases.

Numerical Simulation of Biomechanical Behaviours in Novel Dental Restorations

2014 ◽  
Vol 553 ◽  
pp. 327-331 ◽  
Author(s):  
Zhong Pu Zhang ◽  
Ke Ke Zheng ◽  
Ting Ting Le ◽  
Wei Li ◽  
Michael V. Swain ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Fracture Resistance ◽  
Early Stage ◽  
Two Dimensional ◽  
Prevention Strategies ◽  
Minimal Intervention ◽  
Tensile Stresses ◽  
Dental Restorations ◽  
Decayed Tooth ◽  
Mechanical Strengths

Besides the prevention strategies against early stage dental caries, restoration is a preferable way to prevent decayed tooth from further deterioration. This study aimed to compare the mechanical strengths of carious tooth, traditionally restored tooth, and novel conservatively restored teeth under occlusal loading. The two-dimensional (2D) finite element method (FEM) was applied to quantify and compare maximum tensile stresses thereby predicting the initiation of crack. Taking into consideration of peak tensile stresses, it was found that the conservative (minimal intervention) restorations exhibited better fracture resistance than traditional restoration.

scholarly journals Deployable Structures in Plants

2008 ◽  
Vol 58 ◽  
pp. 31-40 ◽  
Author(s):  
Hidetoshi Kobayashi ◽  
Keitaro Horikawa
Keyword(s):  
Numerical Simulation ◽  
Numerical Methods ◽  
Kinetic Energy ◽  
Leaf Area ◽  
Plane Surface ◽  
Early Stage ◽  
Point Of View ◽  
Constant Speed ◽  
Total Kinetic Energy ◽  
Deployable Structures

The deployment of leaves with plane surface and straight parallel folds, as observed in leaves of hornbeam and beech, was investigated by using numerical methods. In both species the veins are angled at 30° to 50° from the midrib, when the leaves are outstretched. Although a higher angle allows the leaf to be folded more compactly within the bud, it has very small leaf area in the early stage of unfolding. The midrib of leaf grows very slowly at first and then it does with an almost constant speed. From the numerical simulation, it was found that the midrib grows with the minimum unfolding energy. The deployment of flowers was also investigated from mechanical point of view. A potato flower has five or six petals with triangle gussets between petals. The bud volume becomes largest when the number of petals, N, is five. However, the energy for unfolding of the model with N = 5 or 6 is smaller than those of other models, if the energy can be represented by the total kinetic energy during unfolding.

scholarly journals Impact of aerosols and turbulence on cloud droplet growth: an in-cloud seeding case study using a parcel–DNS (direct numerical simulation) approach

2020 ◽  
Vol 20 (17) ◽  
pp. 10111-10124
Author(s):  
Sisi Chen ◽  
Lulin Xue ◽  
Man-Kong Yau
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Early Stage ◽  
Cloud Condensation Nuclei ◽  
Hybrid Approach ◽  
Onset Time ◽  
Relative Dispersion ◽  
Droplet Radius ◽  
Droplet Growth ◽  
Cloud Seeding

Abstract. This paper investigates the relative importance of turbulence and aerosol effects on the broadening of the droplet size distribution (DSD) during the early stage of cloud and raindrop formation. A parcel–DNS (direct numerical simulation) hybrid approach is developed to seamlessly simulate the evolution of cloud droplets in an ascending cloud parcel. The results show that turbulence and cloud condensation nuclei (CCN) hygroscopicity are key to the efficient formation of large droplets. The ultragiant aerosols can quickly form embryonic drizzle drops and thus determine the onset time of autoconversion. However, due to their scarcity in natural clouds, their contribution to the total mass of drizzle drops is insignificant. In the meantime, turbulence sustains the formation of large droplets by effectively accelerating the collisions of small droplets. The DSD broadening through turbulent collisions is significant and therefore yields a higher autoconversion rate compared to that in a nonturbulent case. It is argued that the level of autoconversion is heavily determined by turbulence intensity. This paper also presents an in-cloud seeding scenario designed to scrutinize the effect of aerosols in terms of number concentration and size. It is found that seeding more aerosols leads to higher competition for water vapor, reduces the mean droplet radius, and therefore slows down the autoconversion rate. On the other hand, increasing the seeding particle size can buffer such a negative feedback. Despite the fact that the autoconversion rate is prominently altered by turbulence and seeding, bulk variables such as liquid water content (LWC) stays nearly identical among all cases. Additionally, the lowest autoconversion rate is not co-located with the smallest mean droplet radius. The finding indicates that the traditional Kessler-type or Sundqvist-type autoconversion parameterizations, which depend on the LWC or mean radius, cannot capture the drizzle formation process very well. Properties related to the width or the shape of the DSD are also needed, suggesting that the scheme of Berry and Reinhardt (1974) is conceptually better. It is also suggested that a turbulence-dependent relative-dispersion parameter should be considered.

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