Validation of CORMIX and CorJet models for dense effluent discharge from multi-port dischargers with a 60 degree angle

In today's world, fresh water is known as a limited resource that all economic and social activities of human beings and more importantly human life and other organisms depend on this limited resource and this limited resource is decreasing day by day. At present, in most countries, desalination of the seas and oceans is the most important source of water supply near the coast. One of the products of desalination plants is saline effluent that is discharged into the sea environment. Improper discharge of this effluent causes damage to the environment and can cause irreparable damage to human life and other organisms. Due to the fact that the use of multichannel dischargers has increased in recent decades, it is necessary to conduct numerical and laboratory studies on these types of dischargers. Many studies have been performed to validate CORMIX and CorJet models for effluent discharge using single-channel dischargers, but so far the accuracy of these models for dense effluent discharge using multi-channel dischargers has not been investigated. For this reason, in this research, the validation of CORMIX and CorJet models is investigated to investigate the flow of saline effluent discharged from multi-channel dischargers in a static and dynamic environment.

CORMIX is a hydrodynamic model that uses flow classification to investigate the behavior of effluents with positive, negative and neutral buoyancy in the aquatic environment. Predicting the behavior of the effluent in the distant field, considering the wind flow, roughness and slope of the bed are among the features of this model. CORMIX consists of three sub-models: CORMIX1 (discharge using single-channel discharge), CORMIX2 (discharge using multi-duct discharge) and CORMIX3 (surface discharge) .Corjet is an accurate, three-dimensional integration model for analyzing the concentration and flow path of discharged effluents in the aqueous medium. This model is a subset of the CORMIX model and can be run directly or independently of the CORMIX system. This model solves the equations and predicts the dilution of effluents with positive, neutral and negative densities based on the Eulerian integral method.CorJet is used for single-channel and multi-channel dischargers. A feature of this model is the integration of jets in multichannel unloaders. This model does not consider any boundaries and only applies to near field and does not predict dilution in far field.

As the discharge distance from each other increases, the dilution of the effluent at the point of impact with the ground increases almost linearly. The results of the CorJet model are in good agreement with the results of the laboratory study. In contrast, the results of the CORMIX model for diluting the effluent from multi-channel dischargers in the residential environment are 62% more erroneous than the results of the experimental study and are not reliable. The CorJet model estimates the value of Xi well with an average error of 11%, and as the horizontal distance between the dischargers increases, the error rate between the model results and the experimental study decreases. But the CORMIX model predicts the horizontal distance of the point of impact of the effluent to the ground with a high error. CORMIX and CorJet overestimate the maximum jet climb height if the horizontal discharge distances are close to each other. The results of CORMIX and CorJet models for predicting effluent dilution at the point of impact in dynamic environments differ by 48 and 18%, respectively, for different discharge distances from each other. In this case, the CorJet model estimates the amount of effluent dilution at the point of impact with less error than the CORMIX model. Comparing the results of CorJet and the laboratory study, it can be seen that CorJet predicts the height of the jet ascent in direct and non-direct current with an error of about 33% and 20%, respectively. CORMIX also estimates the maximum ascent height of the jet in direct and non-direct flow mode with a difference of about 13 and 7%, respectively. According to the results, the CORMIX model predicts the maximum ascent height of the jet in dynamic environments with less difference than the CorJet model.

In this research, multichannel dischargers were simulated in static and dynamic environment using CORMIX and CorJet models and the results were compared with the results of laboratory studies. According to the results, the CorJet model estimates all the parameters of the discharged condensed effluent (Si, Xi and Z) from the multi-channel dischargers in the static and dynamic environment with acceptable error. But the CORMIX model only estimates the maximum ascent height of the effluent jet in the dynamic environment well and estimates the other parameters of the discharged effluent with a high difference.