3D numerical modeling of circulations associated with a submerged buoyant jet in a shallow coastal environment

摘要

A three-dimensional (3D) numerical model was applied to examine the buoyant jet-driven circulation in Port Moody Arm, Canada. The Arm, which has a relatively shallow water environment of 5-30 m depth, receives considerable cooling water from Burrard Thermal Generating Station. The cooling water behaves as a typical submerged buoyant jet and has significant impact on the natural circulation of the receiving water. In order to resolve the sharp gradients in the hydrothermal field and overcome the scale barrier between the far-field and near-field zones of the submerged buoyant jet, a newly developed embedded grid scheme was incorporated into the model, which solves the complete field with a single modeling procedure using a pre-conditioned conjugate gradient approach. Special care was taken with the turbulence diffusion and jet entrainment by using a second order turbulence closure model and the Smagorinsky formula. The simulated buoyant jet was calibrated using an integral model matched to empirical jet data; modeled velocity and temperature profiles were quantitatively verified as being in good agreement with the available observations. After the modeled flow pattern was qualitatively verified with data from historical dye-tracing surveys, extensive simulations were carried out to examine circulation behavior under the impact of the buoyant jet.