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This paper investigates the evolution of oblique sand jets passing through a thin layer of oil and entering to stagnant water known as oily sand jets. The jet evolution parameters include the frontal position, the trajectory of particle clusters, the frontal width, the area of oily sand clusters, cloud velocities, and bursting times. Two scaling parameters, known as aspect ratio and particle to nozzle size ratio, were found to control the evolution of oily sand jets. The results show that the ratio of nozzle to sand particle size can cause particle channelization which can significantly alter motion of particle clusters in stagnant water. Moreover, the aspect ratio indicating the correlation between sand mass and nozzle diameter describes the dispersion of particle clusters during evolution of oily sand jets. The frontal width of the oily sand jet was measured during the experiment and the results were compared with the width of vertical sand jets in water. The results show that the width of the oblique oily sand jets increased as oily sand jets descended in the water. In addition, the frontal width of oily sand jets was found to be greater than the frontal width of vertical sand jet without an oil layer. Experimental observations indicated that the channelization effect initiated when the nozzle diameter is more than thirty-six times of mean particle size. The centroid of oily sand jets in vertical direction increased by 50% due to channelization effect.

Background: Treatment of combined industrial wastewater from industrial parks is one of the most complex and difficult wastewater treatment processes. Also, the accuracy of biological models for the prediction of the performance of these processes has not been sufficiently evaluated. Therefore, in this study, the International Association on Water Quality (IAWQ(-Activated Sludge Model No. 1 (ASM1) was implemented for the Jey industrial park in Isfahan province, Iran. Methods: The Jey IPWWTP process is a combination of anaerobic and aerobic biological processes. To evaluate the overall performance of IPWWTP, organic compounds, suspended solids, nutrients, attached biomass, and some operating parameters were measured during 6 months. Then, the biokinetic coefficients of aerobic processes were determined using Monod equations. Finally, the aerobic processes were modeled using ASM1 implemented in STOAT software. Results: The values of the biokinetic coefficients K, Y, Ks, Kd, and µmax were calculated as 2.7d- , 0.34 mg VSS/mg COD, 133.36 mg/L COD, 0.03d- , and 0.93d- , respectively. Based on the default coefficients and conditions of the ASM model, the difference between the experiments and model prediction was about 2 to 98%. After calibrating the ASM model, the difference between the experiments and prediction in all parameters was reduced to less than 10%. Conclusion: Investigations showed that the default coefficients and operation conditions of the ASM1 model do not have good predictability for complex industrial wastewaters and the outputs show a low accuracy compared to the experiments. After calibrating the kinetic coefficients and operating conditions, the model performance is acceptable and the predictions show a good agreement with the experiments.

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The water entry, crown formation, and cavity dynamics of gravity-driven thick solid and annular disks were studied by conducting laboratory experiments. Three different release conditions were examined to study the fully guarded and partially guarded release conditions on the cavity dynamics. The effects of aspect ratio, geometry, and density of disks on crown formation, interface impact, seal development, and air entrainment were investigated. The crown structure was classified based on the dimensionless moment of inertia and the impact Froude number. The crown dimensions were measured and smaller crown geometries were found in annular disks. The total duration of crown formation and destruction was measured which is a critical parameter in water entry problems due to its correlation with momentum transfer and energy dissipation rate. The temporal variations of the cavity dynamics were investigated and it was found that the growth rate of normalized pinch-off depth had a logarithmic correlation with time. The disk's velocities in three different stages were measured and it was found that the settling velocities followed a linear relationship with I* and it was affected by the release conditions. The velocity and vortex fields were extracted from the Particle Image Velocimetry (PIV) data. The velocity fields showed that the solid disks affected a greater surrounding ambient in comparison to the annular disks due to their higher initial momentum. Periodic vortex shedding was formed in the wake of annular disks and the frequency of the vortex field was found to be proportional to the disk density.