Modified description for deposition of particles in small volumes

Abstract

Abstract Different elements that control the concentrations and doses from radioactive particles are in need to be elaborately studied. From theoretical point of view, this requires improving the models that describe the controlling elements of the behaviors and dynamics of the particles. An important element is the deposition of the particles onto surfaces within small volumes, like gaps in buildings’ shells. This element is studied in this article by developing a modified theoretical scheme built by starting with the Fick;s 1st law of diffusion . Velocities of depositions are calculated by taking into account the turbulent and brownian diffusion mechanisms within the boundary layer . The dependence of the particle’s eddy diffusion coefficient on the distance close to the surface is expressed by a fourth power relation. This relation has only one free parameter. The model considers the boundary layer to be composed of only one region. The value of the free parameter is determined in relation to the friction velocity . Particles sizes of 1 nm – 100 μ m are studied. The obtained resulted are presented in comparison to one of the famous theoretical models. Agreeing with experiments, the proposed model shows a promising success and provides a deeper vision to describing the turbulence inside small-sized spaces. Additionally, it gives a new definition to the form and size of the boundary layer .