Tez özetleri Astronomi ve Uzay Bilimleri Anabilim Dalı

Application of Visual Plumes Model on Dense Wastewater Discharge Initial Dilution

Especially physical and chemical pollutants including dense wastewater discharges, which are originated from mine effluent, brine or cold water and they are denser than receiving water, are a lesser investigated issue comparing positively buoyant wastewater discharge such as domestic wastewater etc. into marine, ocean etc. huge receiving water ambient. In order to design marine outfall obeying environmental regulations pollutant limitation standards, it is necessary to determine or estimate by calculations wastewater jet geometries and dilutions under discharge conditions. Mathematical models are used for estimation of outfall originated wastewater jet geometry and dilutions in various locations and numerical model computer programs are utilized for quick calculations. Numerical models were prepared for general purposes for positively buoyant jet characterized discharges because of the fact that most of designations were needed for domestic wastewater discharging marine outfalls. So, validation studies for these numerical model programs were mostly performed for positively buoyant wastewaters and confirmation studies of these computer programs were arranged by experimental data sets comparison then solved their problems. However, numerical model programs are also required this kind of validation investigations and if possible increase the accuracy of the estimation calculations for dense jet including outfalls.

In this study, validation level determination and estimation calculation sensitivity increase investigation of “Visual Plumes” (VP) computer program, which is one of the main program for sea outfall design used for determination of dense wastewater discharges’ jet geometry and initial dilution calculations and produced by USA Environmental Protection Agency (U.S. EPA), were performed . In this study, experimental dense jet geometrical parameters and dilutions data sets of dense jets of dense wastewaters with vertical inclination angles of one singular circular discharge nozzle which were discharged into stagnant, homogeneous water ambient, which were obtained by Nemlioglu via 3D LIF (3 dimensional laser induced fluorescence) method, were taken into account than application of same conditions of the experiments were performed in VP mathematical computer program’s sub model UM3 for comparison. Inclination angles of dense jets were θ₀= 0º, 15º, 30º, 45º, 60º, 75º and 90º, flow conditions were arranged for gravimetric Froude number F=20 approximately, and Reynolds number Re=2200 were selected for turbulent flow conditions in the reference experimental study. Finally, experimental and VP estimated dense jet geometrical parameters and “impact point dilution” values, which contains initial dilution, were compared each other than validation levels of VP for per parameters were determined. Difference percentage of experimental-VP values for per parameters were obtained and compared with deviation amount of sequential experiments, which were adopted for acceptable level. As a result, following results were found: VP performs calculations only can be taken into account until “impact point”, which is the intersection point of dense jet centerline with bottom; VP can not calculate “near field” dilution and its location; and although dense jet’s cross-sections are not circular, VP assumes them circular. In addition, it was determined that VP calculated dense jet parameters have inconstant validation level and these differences vary with jet inclination angle. It was found that validation level of VP, UM3 application for dense jet can be closer 100% using impact point correction coefficient k_i, and internal terminal rise height correction coefficient k_t for jet geometric parameters. As a result of this study, high level validity of VP provided for dense jet geometric parameters with k_i and k_t correction coefficients using for each different parameters and inclination angle range via singular or combined applications. Moreover, it was found that correction coefficients can be estimated for middle inclination angles in 15°≤ θ₀ ≤ 75° range with k_i=0,0104•θ₀+0,962 equation, and in 15°≤ θ₀ ≤ 90° range with k_t=0,0032•θ₀+1,2255 equation.