Effect of Proximity to Bed on 30° and 45° Inclined Dense Jets: A Numerical Study

Employing inclined dense jets is a common way for the disposal of brine from coastal desalination plants. Reaching an optimal design to minimize the negative impacts of brine on marine ecosystems has been a popular environmental-related line of research over the last decades. This paper numerically analyzes the mixing and geometrical properties of 30° and 45° inclined dense jets when they discharge close to the bed. For this purpose, two series of numerical simulations were developed. In the first series, the nozzle was placed far enough from the lower boundary to act as a free jet. Meanwhile, in the second series, the distance between the nozzle tip and seabed was substantially reduced. By comparing these two series, the effect of proximity to bed on the behavior of dense jets has been investigated. The governing equations were solved by modifying a solver within the CFD package of OpenFOAM. The numerical results were presented in comparative figures and were compared to previous works. Comparisons indicated that the numerical model predicts the geometrical characteristics of dense jets in good agreement with the past experimental studies. However, the dilution predictions are conservative. It has been observed that proximity to the bed has almost no appreciable effects on the behavior of 45° jets. However, for 30° jets, when the bed proximity parameter (y0/LM) falls below 0.14, the normalized values of horizontal and vertical locations of centerline peak and return point dilution are slightly reduced while the terminal rise height remains untouched. • The properties of free and boundary-affected dense jets were numerically analyzed. • Some characteristics of 30° jets were found to be influenced by the lower boundary. • The 45° dense jets were insensitive to variations of the bed proximity parameter. • The model predicted the geometric characteristics with reasonable accuracy. • The dilution predictions were found to be conservative.