On the validity of the gradient diffusion approach as applied to modelling particle dispersion in a turbulent gaseous flow

AbstractThis paper develops a criterion for predicting when gradient diffusion should adequately predict the dispersion of particles in simple gaseous turbulent flows such as round jets or the decay region of a grid‐generated turbulent flow. The development of this criterion involves deriving the solution to the gradient diffusion model by another route, where the assumptions required to yield the solution can be carefully considered. This derivation also provides an expression for the particle diffusivity. The model is then applied to two flows where particulate dispersion has been measured experimentally: flow behind a turbulence‐generating grid, and a round jet flow. Under conditions where the criterion for gradient diffusion is satisfied, good agreement is found between measurement and theory.

On the validity of the gradient diffusion approach as applied to modelling particle dispersion in a turbulent gaseous flow Journal Articles