Plume rise modelling: The effects of including a wind shear and a variable surface roughness

Abstract

Using a dynamic plume rise and dispersion numerical model, the importance of accurate specification of the wind profile has been investigated. Plume rise, plume dispersion and the corresponding value of the maximum ground level concentration ( C max) and its distance of occurrence ( x max) are found to be sensitive to the wind profile, largely influenced by the value chosen for the surface roughness parameter. It would appear from these numerical experimental results that improved accuracy can be gained by incorpotaring a logarithmic or function of distance downstream; although it is suggested that the primary copcern should be the accurate specification of the values of the surface roughness close to the stack when the effluent plume is in its initial stages of rise.