Three dimensions advection-diffusion equation in unstable condition

Abstract

The advection-Diffusion Equation in three dimensions was solved using the Separation variable, Substitution and Laplace transform methods, taking into account that eddy diffusivity along the horizontal, lateral coordinates and wind velocity are constant respectively, while the vertical eddy diffusivity is a function of the vertical height "z", Monin- Obukhov length "L" friction velocity at different emission rate and operation of iodine (I-131) in an unstable condition. We took the measured data from Inshas, Cairo, Egypt and compared the concentration of the calculated results with the results obtained from the solution equation at heights of 0.7, 27, and 43 meters. We found that all models are within a factor of two with the observed data from statistical evaluations in unstable conditions, we found that all models fell into a factor of two with the observed data. Whereas with NMSE and FB, the current models correlate better with the observed data.