Expert Systems for Mixing‐Zone Analysis and Design of Pollutant Discharges

Abstract

Water‐quality policy in the United States includes the concept of a mixing zone, a limited area or volume of water where initial dilution of an aqueous pollutant discharge occurs. Given a myriad of possible discharge configurations, ambient environments, and mixing‐zone definitions, the analyst needs considerable training and expertise to conduct accurate and reliable mixing‐zone analysis. The Cornell Mixing Zone Expert System is a series of programs developed to predict the dilution and trajectory of submerged single‐port (CORMIX1), multiport diffusers (CORMIX2), and surface (CORMIX3) discharges of arbitrary‐density (positive, neutral, or negative) into a stratified or uniform‐density ambient environment with or without crossflow. CORMIX gathers the necessary data, checks for data consistency, assembles and executes the appropriate hydrodynamic simulation models, interprets the results of the simulation in terms of the legal requirements including toxic discharge criteria, and suggests design alternatives to improve dilution characteristics. In particular, CORMIX correctly predicts highly complex discharge situations involving boundary interactions, dynamic bottom attachments, internal layer formation, and buoyant intrusions, all features that are beyond the predictive capabilities of other currently available initial mixing models.