摘要
悬移质在水流中的紊动扩散是液体和固体掺混的两相流运动,是许多学科的理论基础。本文从紊动随机模型出发,讨论了悬移质的扩散机理,并建立了随机扩散模型,为该问题的深入研究提供了途径。文中应用这一模型求解了二维、均匀水流悬移物质垂线分布,并证明了以往的扩散理论只是本模型理论的一阶近似。
The progress in modern instruments and measuring technology and the development of random theory of turbulence has made possible the indepth research of turbulent diffusion of suspended particles in flowing water.Starting from the eddy structure of the turbulent current, this paper has derived the relationship between the oscillating flow rate of the suspended particles and the eddy structure, and obtained the probability distribution function for the suspended particles.On this basis, the diffusion model for suspended load is put forward, and the expression for the turbulent diffusion flux of suspended load is derived.This model indicates that the first, second,……, nth derivatives all contribute in the turbulent diffusion, while the previous result is the first approximation of the present model, thus diffusion equations including all derivatives have been put forward.Further study has shown that the function of higher derivatives will decrease rapidly as the number of derivative order increases, therefore relative high precision has already been obtained by the first approximation.This article has derived, on the basis of the statistical theory of turbulent shear flow, the first approximations formula for the vertical distribution of the suspended load, which is consistent with the measured data.The paper also qualitatively discusses the diffusion of solvents in flowing water.
