Contaminant spreading by natural convection in a box

In this paper the spreading of a contaminant accompanied with natural convection in a box is numerically simulated. The box may be considered as a cooking room or a working place where some sources of heat and contaminant are in the simultaneous action. The box floor is supposed to be divided into several domains with different boundary conditions for temperature or heat flux. Here the purpose of the simulation is to understand the contaminant spreading process in the box under the influence of a convective motion. The model can be also applied for an enclosure with separated parts differentially heated by the sunlight on its boundaries. A good knowledge of this process is very useful for setting an efficient ventilation scheme. In this paper the finite difference method based on the Samarski scheme with ADI technique is applied for numerical simulation. Here the box floor is divided into two domains of equal sizes but with different temperature or heat flux. The contaminant source locates in the middle of the box bottom. The simulation shows that over the part of the floor where temperature or heat flux is greater the contaminant concentration is lager. That result is in the accordance with the experiment done in the framework of this~investigation.

Discussions on Fog and Haze Weather Treatment from Planning View — Taking Jinan as Example

Currently fog and haze weather has become a new kind of meteorological and environmental disaster phenomenon. Taking jinan city as an example, this paper analyzed the causes from planning view.One is the absence of traffic environmental bearing capacity in traffic planning;The second is the lack of sufficient attention to ventilation channel planning;The third is unreasonable layout of industrial land. In order to solve these problems, one hand, we should put forward some city planning countermeasures, such as developing public transit system and paying more attention to bicycle lane and sidewalk planning. On the other hand, it is evitable that automobile possession will increase with economy development, so we should pay more attention on roadway and river course ventilation planning, they are helpful for contaminant spreading by forming an atmosphere favorable to emission diffusion. Moreover industrial land should be laid in upstream of minimum wind frequency and downstream of maximum wind frequency. By these means the fog and haze weather can be controlled to some extent.