Numerical Simulation of Haze-Fog Particle Dispersion in the Typical Urban Community by Using Discrete Phase Model

Abstract

The haze-fog particle dispersion in urban communities will cause serious health and environmental problems, which has aroused society attention. The aim of the present investigation is to reveal the underlying mechanisms of haze-fog particle dispersion via Computational Fluid Dynamics (CFD) method, and then to provide a groundwork for the optimal spatial arrangement of urban architecture. The Delayed Detached-eddy Simulation turbulence model (DDES) and Discrete Phase Model (DPM) are utilized to investigate the wind flow distribution and the particle dispersion around the building group. The numerical results show that the particle dispersion is dominated by the incoming wind flow, the layout of architectural space and the type and distribution of vortex. The ‘single body’ wake pattern and the vortex impingement wake pattern are identified in the wind flow field, which have different effects on the distribution of haze-fog particle. The cavity formed by the layout of the building group induces primary vortex and secondary vortex, which will make it more difficult for the particles entering the square cavity to flow out. Moreover, the concentration of the particle in the rear of the buildings is relatively low due the effect of attached vortices.

Numerical simulation and theoretical study on the impact of wind-sand flow of high-speed trains in long tunnel space

“…Firstly, a long tunnel located in the "Qijiaojing" wind-prone area on the second double line of the Lanxin Railway was selected as the object of study. Various geometric and numerical models were determined, and the 3D-DDES model was used instead of the traditional LES standard k-ε turbulence model, which has better mixing-phase simulation performance 22,23 . Secondly, in order to better analyze the impact mechanism and differences of sand-free wind and sand flow on equipment heat dissipation efficiency in a tunnel environment, CFD simulation and analysis were carried out for the flow characteristics of millimeter-scale sand flow under multi-field coupling, particle dispersion characteristics, and transient airflow effects.…”

“…However, it is considered to have better performance in simulating transient wind and sand flows and is more suitable for problems involving the discrete movement of particles. It is an efficient and accurate numerical method 22,23 . The turbulent boundary layer is modeled using the unsteady RANS model with the following expression:…”

Analysis of Diffusion Characteristics and Influencing Factors of Particulate Matter in Ship Exhaust Plume in Arctic Environment Based on CFD

“…The thermodynamic state of ship exhaust diffusion involves both the gas and solid phases, for which the standard k-ε model, the component transport model and the discrete-phase model (DPM) were chosen to simulate the diffusion of exhaust. Among them, the standard k-ε model is used to simulate the flow diffusion of particles and the flow of the external air flow field; the component transport model is used to describe the gaseous composition of the exhaust, and the discrete-phase model is used to simulate the diffusion of the carbon soot particles [37][38][39].…”