# Development and Evaluation of a Fluctuating Plume Model for Odor Impact Assessment
###### Abstract
(2015) [PERSON] et al. (2015), instead, studies the Fluctuating Plume in situations that can be modelled by a Gaussian Plume Model for the average concentration (horizontal homogeneity of meteorological and micrometeorological variables and flat and horizontally homogeneous soil). In fact, these conditions are rather artificial, but can be considered realistic when the ground is flat, and the meteorological conditions are horizontally homogeneous and stationary. Primary focus of that work was to verify how much such a model was able to reproduce the extensive set of experimental measurements obtained by [PERSON] et al. (2015) [PERSON] et al. (2015) in a wind tunnel in substantially neutral turbulence. The important result reached is a semi-analytical expression for the different moments (uncentered) of the instantaneous concentration that reproduces with good approximation the measurements obtained in [PERSON] et al. (2015). Our work starts from the general conclusions reached by [PERSON] et al. (2015), in order to obtain a Gaussian Plume Model for the average concentration and its variance, totally algebraic and simple enough to be useful for design purposes. Based on the knowledge of the values representing the mean and variance, the parameters defining the two-parameter PDF are known, with which it is possible to estimate the peak concentration, defined as an appropriate percentile, at every point in time and space of the considered simulation domain. In order to evaluate the performance of the proposed model, a comparison with the Uttenweiler field dispersion test was conducted [PERSON] et al. (2015). The simplicity of this model makes it useful at least for screening purposes and, in situations with flat and horizontally homogeneous terrain and with horizontally homogeneous meteorology, also for regulatory purposes. Its limitation consists in considering only one active emitting source. In Section 2, the Lagrangian theory of the Fluctuating Plume is initially presented, and from it a new stationary Gaussian Plume formulation is obtained for the average concentration of a generic odorous substance and for its variance, as well as the methodology to be used to obtain the peak concentration. Section 3 briefly presents the Uttenweiler experimental campaign specifically dedicated to the measurement of the average concentration and variance, which was used to verify the behavior of the Gaussian Stationary Fluctuating Plume model here developed. In Section 4, the results obtained using the model developed to reconstruct the Uttenweiler experimental campaign are presented and discussed. Section 5 presents some conclusions. The Gaussian stationary formulation obtained holds only if one emission source is active, but its use in situations of practical interest would require its multisource extension and this is not straightforward. If, in fact, for the average concentration the superposition of the effects holds, so it is not a priori for the variance and for the percentiles, since the turbulence of the PBL somehow correlates the different emission sources. This topic is currently still an open challenge and the Supplementary Material presents some considerations and possible practical solutions. The purpose of the work described in this paper is to obtain a prototypal implementation of the theoretical model presented. Our aim is to obtain a preliminary test of the reliability and the usability of a simple and analytical model to estimate ambient peak concentrations, crucial for odor assessments. Only after a widespread experimental verification, the model will be worthy of a proper operative development, including an official implementation, releases, user's manual, and public distribution.