Author(s): M. M. Ishikawa; T. Bleninger; A. V. Falkenberg; R. C. Barletta; A. B. Trevisan; V. Dos Santos
Keywords: Cormix; Cortime; Time series; Contour maps; Dilution; Exceedance frequency; Near field
Abstract: The increase o f coastal populat ion over the years carries the increase o f waste and the necessity o f the improvement of sanitat ion systems and its expansion. One option for these regions is the ocean disposal by submarine outfalls. To meet the growing demand with quality it is necessary improve the studies concerning the mixing processes and the characterizat ion of near and far field. These two fields have very different characteristics, their divergences do not allow the modelling o f the process with only one model. It is known that the major dilution occurs at the near field and consequent ly it is the most affected region. Therefore, the evaluation o f the efficiency o f submarine outfalls in this region is vital to guarantee the compliance o f the regulat ions. There are basically three methods to solve the mixing process: the empirical, easy and fast to solve; the integral, which regards the velocity and density, but assumes steady state; and the numerical, that describes in detail the mixing but requires t ime and high computational effort. The integral method is commonly used due to the satisfactory results obtained without the necessity o f sophist icated tools. However, it works in steady state while the ambient and discharge condit ions are unsteady. CORMIX is a near field model based on integral methods. The use o f time series can improve the result s of the steady state model, showing the influence of the registered variat ions after running the programme several t imes. CORMIX has a post -processing tool that automat ically run the simulat ions in t ime series, CorTime. It summarizes the dilut ion and plume characterist ics of each t ime step simulated, and make a simple statistical analysis. This work will show post-processed results from CorTime, with the aim of get a bette r spatial visualizat ion of the plume behavior, and have a more specific answer about the compliance o f the system with the regulatory standards. The data used are from studies made in Florianópolis to the installation o f a submarine outfall. The post-processing was made at MATLAB. It was obtained graphs of exceedance frequency (the frequency which the system efficiency is not in compliance), graphs o f the average dilut ion and an video showing the plume variat ions over the t ime. These results assist the analysis of the mixing process, and at the decision making of projects.