烟羽进入内边界层时的扩散

当风从海上吹向陆地,或从农村吹向城市时,下垫面粗糙度迅速变化,并形成一个内边界层(IBL),严重影响烟羽的扩散。本文提出了一个烟羽进入IBL时的动态模式,将扩散过程分为三阶段:(1)进入之前;(2)进入时;(3)进入之后。还提出了烟羽进入IBL时扩散的方差微分方程。该理论模式计算的结果与野外调研和风洞试验十分一致,即在烟羽进入IBL时扩散参数σ₂发生了跳跃。 

Diffusion of A When It Enters an Internal Boundary Layer

When wind blows from sea to land, or from rural area to a city, the roughness length of the ground surface Zo changes rapidly and an internal boundary layer (IBL) will develop from the atep-change in Surface roughness, Internal boundary layer affects diffusion of plume seriously, In this paper we present a dynamic diffusion moder of a plume when it enters a IBL. It divides the diffusion process of the plume into three stages. ( 1 ) outside IBL; ( 2 ) entering IBL;(3) inside IBL, It also presents a differential equation for square deviation of plume diffusion when it enters IBL, The eomputation results of the theoretical model show a good agreement with that of field investigation and that of wind tunnel experiment, that is.a jump in diffusion parameter σ₂ appears when a plume enters an IBL.