Mechanism Of The Flow During The Disappearance Of Foggy Bottom

With the rapid development of economy, the growing pressure of global environment deteriorate, further environmental pollution and disasters are frequently. Recently, a prominent to the rising number of atmospheric environmental problem is the haze, which brings a great challenge for the environment and people’s health. It is worth noting that foggy bottom is a typical representative of weather phenomena. It is of scientific significance to study the mechanism of the disappearance of foggy bottom. Clearly, the characterization of foggy bottom and the understanding of the flow mechanism will be able to provide and the prediction with useful ideas. Accordingly, the corresponding study is of practical significance for predicting atmospheric environmental disasters.In this study, the numerical method was adopted to discuss the convection and heat transfer mechanism in the process of the fog dissipation. The numerical results are consistent with the experiment in Princevac&Fernando. Further, the flow in the cavity with the two working fluids (water and air) was simulated. Clearly, the flow and heat transfer in the cavity is dependent on the Rayleigh number and the aspect ratio. It has been demonstrated that the averaged flow rate and heat transfer in the quasi-steady stage have such approximate relations:QRa5/4～Ra and Nu/Ra1/4≈-0.005for water as the working fluid but Nu/Ra1/4≈-1.15×104for air as the working fluid. Additionally, the flow rate and the Nusselt number are dependent on the aspect ratio. The flow of two fluids varies under different conditions. The flow rate and Nusselt number are larger for A=0.087and smaller for A=0.286in the water case. In the air case, the flow rate is larger for A=0.286and the smaller for A=0.087, but the Nusselt number is smaller for A=0.087and larger for A=0.286. Furthermore, in the preliminary numerical simulation for high Rayleigh numbers, different heat transfer laws were obtained based on the turbulence model.Although this study has characterized the disappearance of foggy bottom during the morning, the quantities of the flow and heat transfer need to be further quantified. This means that it still needs to perform further theoretical analyses and corresponding experiments in order to validate the present numerical simulations.