Performance evaluation by computational fluid dynamics modelling of the heavy gas dispersion with a low Froude number in a built environment

Zhang, Ying; Wang, Longtao; Li, Angui; Tao, Pengfei

doi:10.1177/1420326x19856041

Cited by 8 publications

(5 citation statements)

References 41 publications

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“…Encrypt the mesh closer to the body surface and the tail of the car area. In order to accurately capture the flow details in the boundary layer, the grid nodes of the first prism layer need to be arranged in the viscous bottom layer, and the y+ value should be less than or equal to 1 [37], therefore the thickness of the first boundary layer grid is set to 0.01 mm, and the total thickness of the boundary layer is 2mm. After the verification of grid independence, the number of the mesh remains around 5 million, which has little influence on the calculation results.…”

Section: Research Model and Mesh Strategymentioning

confidence: 99%

Aerodynamic Drag Reduction and Optimization of MIRA Model Based on Plasma Actuator

Lai

Can

et al. 2020

Actuators

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Active flow control of surface dielectric barrier discharge (SDBD) plasma is a technology that converts electrical energy into kinetic energy to achieve flow control. Its main application areas are concentrated in the aviation field. Undoubtedly, few studies have applied it in the field of automobile flow control. Meanwhile, during high-speed driving, there is a serious airflow separation phenomenon at the rear of notch-back cars, which brings a large area of negative pressure to the back of the cars. Due to the huge pressure difference between the front and end of the cars, it will increase the driving drag and fuel cost of the car. In this context, we seek to discuss the control effect on the airflow separation at the rear of the notch-back by using the phenomenological numerical simulation method of plasma flow control. Firstly, the plasma actuator is arranged separately on the rear end of the roof, c-pillar, upper and side of the trunk to study the control effect of airflow separation. After that, the plasma actuators at each position are combined and actuated simultaneously. We try to observe the control effect of airflow separation and select the combination with the best drag reduction effect. In the third stage, an efficient global optimization (EGO) algorithm based on kriging response surface is applied to optimize the supply voltage of the best combination that has been obtained before and obtain the driving voltage parameter of each actuator optimized under this combination. The results show that when plasma actuation is applied at four locations, only the actuation applied to the side of the luggage compartment has a significant drag reduction effect, while in other cases, the drag coefficient will increase. Specifically, drag reduction is better when the actuation is applied at four positions simultaneously. The maximum drag reduction coefficient of the car is reduced by 13.17%.

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Section: Research Model and Mesh Strategymentioning

confidence: 99%

Aerodynamic Drag Reduction and Optimization of MIRA Model Based on Plasma Actuator

Lai

Can

et al. 2020

Actuators

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“…The utilized parameters were: turbulent Schmidt number (Sc t ), turbulent viscosity (µ t ), turbulent diffusivity (D t ) and the diffusion coefficient for CO into air (D i,ma ) [13] as an ideal gas behavior: Simulating turbulence within carparks is traditionally achieved with the standard k-ε turbulence model with the standard wall function [13] or the re-normalized (RNG) k-ε model [48]. However, the shear-stress transport (SST) k-ω model was adopted in the current due to its advantage of computing flow separation from smooth surfaces [28,49],…”

Section: Governing Equationsmentioning

confidence: 99%

Effects of Cross Level Air Interaction within Multilevel Underground Carparks on Indoor Air Quality

Al-Waked

Yassin

Adwan

et al. 2020

Fluids

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Ventilation for underground carparks is critical to indoor air quality (IAQ) due to carbon monoxide (CO) emissions from cars. The IAQ within a multi-level underground carpark of a shopping mall has been investigated using computational fluid dynamics (CFD) model based on ANSYS-FLUENT (18.1) software. The effects of car engines types, porosity of supply and exhaust air louvers and ventilation flow rates on IAQ were examined. A mesh sensitivity study was conducted and the CFD model was validated against the fully mixed mathematical formulations of IAQ with a maximum difference in values of 1.5 ppm and an error of 3.4%. The results showed that the ventilation system must be operated at ACH value of more than 2.7 in order to meet the required CO concentration of 50 ppm within the carpark and should be based on running cars within each level rather than the parking capacity of each level. Porosity of louvers affected air flow distribution between parking levels and led to higher dilution of CO. Therefore, modelling a multilevel underground carpark requires closer attention to cross level interaction across Ramps which could affect the CO concentration within a given level.

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“…6 During leak accidents, toxic gases may be released, generate clouds near buildings and penetrate the indoor environment, which can lead to severe consequences to human health. 7 Given the high toxicity and corrosive properties of gaseous hazardous chemicals, it is necessary to investigate toxic gas building ingress for different realistic scenarios.…”

Section: Introductionmentioning

confidence: 99%

Modelling of hazardous chemical gas building ingress and consequence analysis during a leak accident

Zhang

et al. 2022

Indoor and Built Environment

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Leakage of hazardous chemical gases during storage or transport via roadways is a common type of accident that threatens human life. This study built a typical residential building model in rural areas of southern China based on Building Information Model technology. The model was then simplified and employed as a target building to simulate the hazardous gas dispersion around it after a leak accident by means of Computational Fluid Dynamic methods. A dose-response model was combined with a probit function analysis to quantitatively identify the exposure risks for different scenarios. The impacts of source location and ventilation path on the dispersion characteristics were analyzed through comparisons of indoor concentration distributions. In addition, the study also quantified the relationship between individual mortality risk and the source intensity by employing H2S as a source of toxic substances. If the source strength was increased by 2.5 times for the same ventilation path, the corresponding mortality rates can improve from 0.1 to 99%. The findings provide effective information about rapid consequence evaluation after accidental leakage of hazardous chemical gas and could be helpful in proposing effective emergency measures to minimize the exposure risk in roadside buildings.

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Performance evaluation by computational fluid dynamics modelling of the heavy gas dispersion with a low Froude number in a built environment

Cited by 8 publications

References 41 publications

Aerodynamic Drag Reduction and Optimization of MIRA Model Based on Plasma Actuator

Aerodynamic Drag Reduction and Optimization of MIRA Model Based on Plasma Actuator

Effects of Cross Level Air Interaction within Multilevel Underground Carparks on Indoor Air Quality

Modelling of hazardous chemical gas building ingress and consequence analysis during a leak accident

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