烟气羽流时空混沌行为的耦合映象格子模型研究

为研究烟气羽流的时空混沌行为,本文从烟气羽流的N-S动量方程出发,根据浮力羽流的半经验公式,对方程中相应的项进行替代、化简,然后无量纲化,得到了以烟气羽流的动量通量m为系统状态矢量的单向耦合映象格子模型.计算了不同参数变化时,耦合周期窗口的时空行为发展,并且进行了李雅普诺夫指数λ计算.分析表明,开放系统中的烟气羽流会出现形态的多重性,包括时空混沌行为.这是由于烟气羽流系统内各种非线性作用的相互影响,也就是方程粘性项、浮力项和惯性项作用强弱对比的变化,以及系统行为发展的不可逆性所导致.

Study on smoke-plume spatiotemporal random behavior in coupled map lattice

This article aims to present a coupled map lattice model initiated by the author to explore the spatiotemporal random behavior of smoke plume. The model is actually deduced from Navier-Stokes equation and modified by using an empirical formula of the buoyant plume. The spatiotemoral behaviors of smoke-plume are numerically simulated by adjusting different non-linear parameters, with the corresponding Lyapunov exponents considered. The results show that there are multiform behaviors in the floating process of the smoke plume in the free space, including its irregular spatiotemoral behaviors. The rationales are that some nonlinear factors affect each other in smoke plume and the floating process is nonreversible, such nonlinear factors, with physical characters of each part being equal, are viscosity, buoyancy and inertia.